99 Mineral nutrition of rice and post-harvest soils influenced by self-made organic composts S. Akter*, H. R. Khan and M. K. Saha Department of Soil, Water and Environment, University of Dhaka, Dhaka 1000, Bangladesh Abstract Using self-made organic composts i.e., rice hull compost (RHC), rice straw compost (RSC), sawdust compost (SDC), and Vermicompost (V) an experiment was conducted to evaluate their responses on mineral nutrition of rice and post-harvest soils under field condition. The total nitrogen contents among the treatments ranged from 9.6 - 21.4, phosphorus: 1.1 – 4.42, potassium: 3.86 - 7.27, sulfur: 11.9 – 19.7, calcium: 3.30 – 11.87 and magnesium: 2.76 – 5.54 g kg-1 at the maturity stage of rice plants which were found to be positively influenced by the applied organic composts. The nutrient status of the post-harvest soils was also influenced by the applied organic composts. The maximum amount of 78.29 mg kg-1 available N was recorded in the T3 treatment, where available nitrogen content increased by 85.65% as compared to the control plot. There were signifi- cant (p ≤ 0.05) increases in other nutrient contents with the increased doses of the composts under rice production. Keywords: Nutrition of rice plant; Post-harvest soils; Self-made organic compost; Suitable source *Corresponding author’s e-mail: suma.soil93@gmail.com Available online at www.banglajol.info Bangladesh J. Sci. Ind. Res. 58(2), 99-106, 2023 Introduction Rice (Oryza sativa L.) is the second most important staple food as it fulfills the dietary requirement of over half of the human population and considers the major food crop of economic significance in Asia (Ahmed et al. 2021). Among South Asian countries, Bangladesh ranks second in terms of areas and production of rice, where it is being cultivated on over 82% of the total cropped land, while Aman rice shares over 37% of total rice production (BBS, 2020). In the coun- try, with advancement of time, nutrient mining increases due to increasing cropping intensity (191%; BBS, 2017), use of modern varieties, nutrient leaching, gaseous loss, soil erosion and imbalanced application of fertilizers with no or little addition of organic manure. To ensure the food security of the increasing population, high-yielding rice cultivars are being cultivated on large scale with intensive use of chemical fertil- izers, which not only degraded soil fertility but also polluting associated environments and affecting food chain and ultimately affect human health. Higher is the crop yield, higher is the nutrient removal from soil. Nutrient deficiency in this country’s soils has arisen chronologically N, P, K and S (Jahiruddin and Satter, 2010). About 45% of net cultivable areas of Bangladesh contain less than 1% organic matter (FRG, 2012). Organic manure is a good source of nutrients, especially N, P and S and it's a good means of soil rejuvena- tion (Jeptoo et al. 2013). So, use of organic matter could be an inevitable practice in the coming years for ensuring sustainable crop productivity without affecting soil fertility (Heikamp et al. 2011). Numerous actions have been taken to improve soil fertility and productivity. The most effective measure is increasing the organic input, such as application of organic manure or compost (Xin et al. 2017) and straw incorporation (Zhang et al. 2016). Crop straw, an easy-to-get, nutrient-rich resource, has great value for improving soil fertility (Tan et al. 2017). Several studies have reported that crop straw is rich in nutrients and organic materials, can be treated as a natural organic fertilizer, and used as an alternative to chemical fertilizers (Wang et al. 2017). Therefore, straw amalgamation seems hopeful to maintain and restore soil fertility. However, until now, the use of straw incorporation to increase crop yield is still a matter of argument since studies in different climates and soil types have led to inconclusive results (Pituello et al. 2016). It has been reported that straw incorporation has significant valuable effects on crop yields and soil properties. For instance, straw incorporation can increase crop yields (Yang et al. 2016), soil organic matter and other soil nutrients (Zhang et al. 2018). Straw return can also improve soil physical properties, such as by increasing hydraulic conductivity, decreasing bulk density, and enhancing aggregate forma- tion (Yang et al. 2016). Vermicompost is a nourishing organic fertilizer having high amount of humus, nitrogen 2–3%, phosphorous 1.55–2.25%, potassium 1.85–2.25%, micronutrients, more beneficial for soil microbes like ‘nitrogen fixing bacteria’ and mycorrhizal fungi. Vermicompost has been scientifically proved as miracle plant growth enhancer (Guerrero, 2010). Ansari and Ismail (2012) reported that worms vermicompost contains 7.37 % nitrogen and 19.58% phosphorous as P2O5. Microbial population of N2- fixing bacteria and actinomycetes increases by the application of vermicompost. The amplified microbial activities improve the availability of soil phosphorous and nitrogen. Vermicomposting is an aerobic, biological method and is proficient to convert eco-friendly hummus like organic substances (Chanda et al. 2011). Vermicompost stimulates to influence the microbial activity of soil, increases the availability of oxygen, maintains normal soil temperature, increases soil porosity and infiltration of water, improves nutrient content and increases growth, yield and quality of the plant (Arora et al. 2011). Rice hull and sawdust are also important agricultural amendments. Growth and yield components of rice grown in saline soil were found to be increased significantly (p ≤ 0.05) by the application of rice hull, rice straw and sawdust alone and in combination (Akter et al. 2018). The physico-chemical properties and nutrient status of post-harvest soils were also found to be influenced by the application of these amendments (Akter and Khan, 2019). Composting is a low-cost natural way of recycling and stabilizing organic matter under thermophilic temperature that forms a pathogen-free substrate, beneficial to crops (Gurtler et al. 2018; Somerville et al. 2020). Low-income farmers found it more advantageous to them. Composting was found to be a promising practice that brought organic materials to a certain stage by narrowing down its C:N ratio where nutrients are easily accessible to plants (Palaniveloo et al. 2020). Partey et al. (2018) and Dinesh et al. (2011), had consolidated that biomass needs to decompose for making N available to crops. Thus, composting locally available organic amendments (OAs) is essential for a healthy and sustainable agro-ecosystem in different climatic conditions. Therefore, the objectives of the study were to evaluate the nutrient statuses of post-harvest soils and rice plants grown in Aman season as influenced by the different rates of organic composts applied under field condition. Materials and methods Study site and experimental design In Patuakhali a district of Bangladesh, the field experiment was conducted in Bilbilash of Bauphal Upazila (Map I), which is located between 22°20ʹ00ʺN and 90°20ʹ00ʺE longitude within agro-ecological zone-13 named as Ganges Tidal Floodplain. The climatic condition of this area is usually known as ‘tropical monsoon climate’. The area mainly enjoys three seasons such as rainy, dry and summer season. The experiment was carried out following completely randomized block design with the self-made organic composts, such as, Rice Hull Compost (RHC), Rice Straw Compost (RSC), Sawdust Compost (SDC) and Vermicompost (V) corresponding to the rates of 0, 2, 4 and 8 t ha-1 of each organic compost at Aman season during August to December, 2018. There were 13 plots having individual treatment (Table I) in the experimental area, each unit plot size was 16 m2 (4m×4m) and replications were considered within the plot. Selected properties of potential amendments used and initial soils at field site are presented in the Tables II and III. Transplantation following subsequent protocols Basal doses of N, P2O5, and K2O from urea, TSP, and MoP fertilizers were applied at the rates of 40, 30, and 15 kg ha-1, respectively considering soil amendments and initial contents of the nutrients. During field preparation, the TSP, MoP, and half of the urea were applied in their entirety after being thoroughly mixed with the field soil. The remaining urea was top dressed in two splits, one at the beginning of the rice panicle and another at the active tillering stage. Three seedlings per hill of the BR 25 variety, which were thirty days old and in good health, were transplanted. Row to row and hill to hill distances were each 20 and 22 cm, respectively. No irrigation was required for this study for the growth of rice in this season. Intercultur- al operations such as, weeding, pesticide use, etc. were done as per requirement. Sample collection and analyses Plant samples were collected from each plot just after harvesting. Soil samples were collected from 3 spots as replications of each plot of active root zone (0-15 cm) with the help of an auger. Soil samples were then stored treatment wise in polythene bags with proper labeling. After sun drying and grounding the samples were then passed through 2 mm sieve and stored properly in air tight plastic pots for further analyses. The collected plant samples were sun dried and weighed. After sun drying a portion of the collected plant samples were oven dried at 65⁰C and then grinded and stored in air tight plastic pots for laboratory analyses. All the labora- tory analyses were done following standard methods. Statistical analyses Pearson correlation and regression analyses between treatments and mineral nutrition of rice plants, Analysis of Variance (ANOVA) and Tukey’s Range Test at 5% (p≤ 0.05) level were done for the interpretation of the experi- mental results. Results and discussion Mineral nutrition of rice plants The total nitrogen, phosphorus, potassium, sulfur, calcium and magnesium contents at maturity stage of rice plants grown under field condition were significantly (p≤0.05) influenced by the application of variable indigenous organic amendments (rice hull compost, rice straw compost, sawdust compost and vermicompost) during Aman season (Table IV and Fig.1). Pearson correlation and regression analyses have been performed between the different treatments and mineral nutrition of rice plant tissues (Table V). Significance has been determined based on p values whether they were <0.05 or not. The total nitrogen (r = 0.78***), phosphorus (r = 0.77**), potassium (r = 0.75**), sulfur (r = 0.82***), calcium (r = 0.82***) and magnesium (r = 0.60*) contents of the tested rice plant (BR 25) tissues were signifi- cantly correlated with the applied organic composts and these correlations confirmed that the different sources of organic materials positively influenced the nutrition of rice plant tissues which ultimately regulate the edible part (grain) of the rice crops. According to Graham et al. (2012), people taking cereal based diets still suffering from hidden hunger of nutrients due to low level and low bioavailability of essential elements. The present results demonstrated that the nitro- gen content in rice straw increased with the increased rate of the application of organic composts. The maximum nitrogen contents in the rice plant tissues were recorded at V8 treatment for the tested variety. Among the applied composts, vermicompost (18.63 g kg-1N) ranked first followed by rice straw compost (17.40 g kg-1), sawdust compost (14.57g kg-1) and rice hull compost (13.33 g kg-1), regardless of their doses. Phosphorus contents in rice plant tissues increased with the higher rates of the different composts. The highest (4.42 g kg-1) and lowest (1.10 g kg-1) contents of total phosphorus were recorded in the T12 (V8) and T0 (control) treatments. The rest of the above-men- tioned nutrients were exerted the similar trends as those obtained by the P and N contents by the different organic composts. The nutrition of rice shoots was influenced by the direction of vermicompost > rice straw compost > sawdust compost > rice hull compost for the studied variety of rice grown under field condition. Nutrient status of post-harvest soils Rice production during T. Aman season, the available N contents in the post-harvest soils increased significantly (p ≤ 0.05) by the application of vermicompost, rice hull compost, rice straw compost and sawdust compost (Table VI and Fig. 2). The maximum amount of available N (78.29 mg kg-1) was recorded in T3 (RHC8) treatment, where available nitrogen content increased 85.65% as compared to control plot. At the same dose (8 t ha-1), the sawdust compost treatment ranked second for the available nitrogen content (62.31 mg kg-1) at post-harvest soils followed by RSC8 treatment (60.76 mg kg-1). There were significant (p≤0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of the organic amendments under rice production (Table VI). Soils treated with vermicompost at the rate of 8 t ha-1 was found to have significantly more phosphorus (12.57 mg kg-1) as compared to control plot. The rice straw compost and sawdust compost each at 8 t ha-1 were showed almost similar trends in the increment of available phosphorus contents in post-harvest soils followed by rice hull compost. The other nutrients of post-harvest soils followed the similar trends as that of phosphorus, except for the exchangeable potassium, where rice straw compost at the highest rate (8 t ha-1) exhibit- ed the best response (0.97 c molc kg -1) than those of the other treatments. The maximum amounts of available sulfur, exchangeable calcium and magnesium were obtained from the highest dose of vermicompost and the minimum amounts were attained by the control plot. The trend of increments of all these nutrients were more pronounced with the higher rates of the applied organic amendments indicate that all the applied organic composts are suitable sources for improving nutrient statuses of soils. Pearson correlation and regression analyses also indicate the strong positive relationship between the treatments and nutrient statuses of post-harvest soils (Table VII). The current findings are in consistent with those of Xin et al. (2017). Many steps have been made to improve soil fertility and productivity, according to them. Increased organic input, such as organic manure, compost, and straw integration, are the most effective approaches. Crop straw, a cheap and nutrient-dense material, offers a lot of potential for enhancing soil fertility (Tan et al. 2017). Crop straw, which is high in nutrients and organic elements, can be treated as a natural organic fertilizer and utilized as an alternative to chemical fertilizers, according to the studies of Wang et al. (2017). As a result, straw integration appears to be a potential method for maintaining and restoring soil fertility, the burning issue of present day. Because, mineral elements are required for the healthy growth and development of both plants and humans. The plant roots take up the mineral nutrients from soil and transported them to the edible parts for human consumption through various transporters. For human health, an ideal future crop should be rich in essential mineral elements but with less toxic elements in the edible parts. Still, it is estimat- ed that nearly 2 billion people are suffering from deficiency of nutrients because of low availability of mineral elements in soil and/or low accumulation/bioavailability of mineral elements in edible parts (Graham et al. 2012). This so-called hidden hunger is an especially serious health problem for people subsisting on cereal-based diets because cereals such as rice usually contain a low level of mineral elements as well as low bioavailability (Grebmer et al. 2014; Nakandalage and Seneweera, 2018). On the other hand, rapid urbanization and industrialization cause contamination by toxic elements in many soils used for crop production (Zhao et al. 2010; Clemens and Ma, 2016), which threaten our health throughout the food chain. Therefore, it is extremely important to boost essential nutrients (both density and bioavailability) and reduce toxic elements in edible parts of cereals for human health. Conclusion The present research findings conclude that the locally made organic composts using indigenous organic materi- als had potential to improve soil fertility and provide nutrients for rice production. Significant positive correla- tion between the treatments and mineral nutrients of rice plants confirmed the strong relationship of organic farm- ing for sustainable agriculture. There were significant (p ≤ 0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of amendments under rice production. The nutrition of rice plants grown under field condition was influenced most by the vermi- compost and followed the order of the treatments as rice straw compost > sawdust compost > rice hull compost for the studied variety of rice. These results resemble that the further researches are needed to find out the suitable doses and types of the amendments. However, the applied organ- ic fertilizers were found to have responses on the nutri- tional statuses of rice shoot and post-harvest soils and these might be effective for the nutritional balance of the rice variety and ultimately will be helpful for country’s penniless people to combat their existing and future demand of quality rice. Acknowledgement The study was carried out under a project of the Climate Change Trust Fund (CCTF) titled ‘Assessment of Impacts of Climate Change on Soil Health and Food Security, and Adaptation of Climate-smart Agriculture in Most Adversely Affected Areas of Bangladesh’ through the MoEFCC, Government of the Peoples’ Republic of Bangladesh. The project was implemented in two phases (Phase I: Jan.’17 to Dec.’18, Code 410 DUand Phase II: Jan.’19 to Dec.’22, Code 573 DU) within six years. We are also grateful to the Project staff and relevant officers/staff of the SWED-DU, DU, MoE and MoEFCC of GoB, who performed for the successful completion of the study. References Ahmed S, Alam MJ, Hossain A, Islam AK, Awan TH, Soufan W, Qahtan AA, Okla MK and Sabagh SI (2021), Interactive effect of weeding regimes, rice cultivars, and seeding rates influence the rice-weed competition under dry direct-seeded condition, Sustainability. 13: 317-321. 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DOI: 10.1146/annurev-ar- plant-042809-112152 DOI: https://doi.org/10.3329/bjsir.v58i2.64570 Received: 26 February 2023 Revised: 17 April 2023 Accepted: 21 May 2023 Mineral nutrition of rice and post-harvest soils influenced by self-made organic composts 58(2) 2023100 However, until now, the use of straw incorporation to increase crop yield is still a matter of argument since studies in different climates and soil types have led to inconclusive results (Pituello et al. 2016). It has been reported that straw incorporation has significant valuable effects on crop yields and soil properties. For instance, straw incorporation can increase crop yields (Yang et al. 2016), soil organic matter and other soil nutrients (Zhang et al. 2018). Straw return can also improve soil physical properties, such as by increasing hydraulic conductivity, decreasing bulk density, and enhancing aggregate forma- tion (Yang et al. 2016). Vermicompost is a nourishing organic fertilizer having high amount of humus, nitrogen 2–3%, phosphorous 1.55–2.25%, potassium 1.85–2.25%, micronutrients, more beneficial for soil microbes like ‘nitrogen fixing bacteria’ and mycorrhizal fungi. Vermicompost has been scientifically proved as miracle plant growth enhancer (Guerrero, 2010). Ansari and Ismail (2012) reported that worms vermicompost contains 7.37 % nitrogen and 19.58% phosphorous as P2O5. Microbial population of N2- fixing bacteria and actinomycetes increases by the application of vermicompost. The amplified microbial activities improve the availability of soil phosphorous and nitrogen. Vermicomposting is an aerobic, biological method and is proficient to convert eco-friendly hummus like organic substances (Chanda et al. 2011). Vermicompost stimulates to influence the microbial activity of soil, increases the availability of oxygen, maintains normal soil temperature, increases soil porosity and infiltration of water, improves nutrient content and increases growth, yield and quality of the plant (Arora et al. 2011). Rice hull and sawdust are also important agricultural amendments. Growth and yield components of rice grown in saline soil were found to be increased significantly (p ≤ 0.05) by the application of rice hull, rice straw and sawdust alone and in combination (Akter et al. 2018). The physico-chemical properties and nutrient status of post-harvest soils were also found to be influenced by the application of these amendments (Akter and Khan, 2019). Composting is a low-cost natural way of recycling and stabilizing organic matter under thermophilic temperature that forms a pathogen-free substrate, beneficial to crops (Gurtler et al. 2018; Somerville et al. 2020). Low-income farmers found it more advantageous to them. Composting was found to be a promising practice that brought organic materials to a certain stage by narrowing down its C:N ratio where nutrients are easily accessible to plants (Palaniveloo et al. 2020). Partey et al. (2018) and Dinesh et al. (2011), had consolidated that biomass needs to decompose for making N available to crops. Thus, composting locally available organic amendments (OAs) is essential for a healthy and sustainable agro-ecosystem in different climatic conditions. Therefore, the objectives of the study were to evaluate the nutrient statuses of post-harvest soils and rice plants grown in Aman season as influenced by the different rates of organic composts applied under field condition. Materials and methods Study site and experimental design In Patuakhali a district of Bangladesh, the field experiment was conducted in Bilbilash of Bauphal Upazila (Map I), which is located between 22°20ʹ00ʺN and 90°20ʹ00ʺE longitude within agro-ecological zone-13 named as Ganges Tidal Floodplain. The climatic condition of this area is usually known as ‘tropical monsoon climate’. The area mainly enjoys three seasons such as rainy, dry and summer season. The experiment was carried out following completely randomized block design with the self-made organic composts, such as, Rice Hull Compost (RHC), Rice Straw Compost (RSC), Sawdust Compost (SDC) and Vermicompost (V) corresponding to the rates of 0, 2, 4 and 8 t ha-1 of each organic compost at Aman season during August to December, 2018. There were 13 plots having individual treatment (Table I) in the experimental area, each unit plot size was 16 m2 (4m×4m) and replications were considered within the plot. Selected properties of potential amendments used and initial soils at field site are presented in the Tables II and III. Transplantation following subsequent protocols Basal doses of N, P2O5, and K2O from urea, TSP, and MoP fertilizers were applied at the rates of 40, 30, and 15 kg ha-1, respectively considering soil amendments and initial contents of the nutrients. During field preparation, the TSP, MoP, and half of the urea were applied in their entirety after being thoroughly mixed with the field soil. The remaining urea was top dressed in two splits, one at the beginning of the rice panicle and another at the active tillering stage. Three seedlings per hill of the BR 25 variety, which were thirty days old and in good health, were transplanted. Row to row and hill to hill distances were each 20 and 22 cm, respectively. No irrigation was required for this study for the growth of rice in this season. Intercultur- al operations such as, weeding, pesticide use, etc. were done as per requirement. Sample collection and analyses Plant samples were collected from each plot just after harvesting. Soil samples were collected from 3 spots as replications of each plot of active root zone (0-15 cm) with the help of an auger. Soil samples were then stored treatment wise in polythene bags with proper labeling. After sun drying and grounding the samples were then passed through 2 mm sieve and stored properly in air tight plastic pots for further analyses. The collected plant samples were sun dried and weighed. After sun drying a portion of the collected plant samples were oven dried at 65⁰C and then grinded and stored in air tight plastic pots for laboratory analyses. All the labora- tory analyses were done following standard methods. Statistical analyses Pearson correlation and regression analyses between treatments and mineral nutrition of rice plants, Analysis of Variance (ANOVA) and Tukey’s Range Test at 5% (p≤ 0.05) level were done for the interpretation of the experi- mental results. Results and discussion Mineral nutrition of rice plants The total nitrogen, phosphorus, potassium, sulfur, calcium and magnesium contents at maturity stage of rice plants grown under field condition were significantly (p≤0.05) influenced by the application of variable indigenous organic amendments (rice hull compost, rice straw compost, sawdust compost and vermicompost) during Aman season (Table IV and Fig.1). Pearson correlation and regression analyses have been performed between the different treatments and mineral nutrition of rice plant tissues (Table V). Significance has been determined based on p values whether they were <0.05 or not. The total nitrogen (r = 0.78***), phosphorus (r = 0.77**), potassium (r = 0.75**), sulfur (r = 0.82***), calcium (r = 0.82***) and magnesium (r = 0.60*) contents of the tested rice plant (BR 25) tissues were signifi- cantly correlated with the applied organic composts and these correlations confirmed that the different sources of organic materials positively influenced the nutrition of rice plant tissues which ultimately regulate the edible part (grain) of the rice crops. According to Graham et al. (2012), people taking cereal based diets still suffering from hidden hunger of nutrients due to low level and low bioavailability of essential elements. The present results demonstrated that the nitro- gen content in rice straw increased with the increased rate of the application of organic composts. The maximum nitrogen contents in the rice plant tissues were recorded at V8 treatment for the tested variety. Among the applied composts, vermicompost (18.63 g kg-1N) ranked first followed by rice straw compost (17.40 g kg-1), sawdust compost (14.57g kg-1) and rice hull compost (13.33 g kg-1), regardless of their doses. Phosphorus contents in rice plant tissues increased with the higher rates of the different composts. The highest (4.42 g kg-1) and lowest (1.10 g kg-1) contents of total phosphorus were recorded in the T12 (V8) and T0 (control) treatments. The rest of the above-men- tioned nutrients were exerted the similar trends as those obtained by the P and N contents by the different organic composts. The nutrition of rice shoots was influenced by the direction of vermicompost > rice straw compost > sawdust compost > rice hull compost for the studied variety of rice grown under field condition. Nutrient status of post-harvest soils Rice production during T. Aman season, the available N contents in the post-harvest soils increased significantly (p ≤ 0.05) by the application of vermicompost, rice hull compost, rice straw compost and sawdust compost (Table VI and Fig. 2). The maximum amount of available N (78.29 mg kg-1) was recorded in T3 (RHC8) treatment, where available nitrogen content increased 85.65% as compared to control plot. At the same dose (8 t ha-1), the sawdust compost treatment ranked second for the available nitrogen content (62.31 mg kg-1) at post-harvest soils followed by RSC8 treatment (60.76 mg kg-1). There were significant (p≤0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of the organic amendments under rice production (Table VI). Soils treated with vermicompost at the rate of 8 t ha-1 was found to have significantly more phosphorus (12.57 mg kg-1) as compared to control plot. The rice straw compost and sawdust compost each at 8 t ha-1 were showed almost similar trends in the increment of available phosphorus contents in post-harvest soils followed by rice hull compost. The other nutrients of post-harvest soils followed the similar trends as that of phosphorus, except for the exchangeable potassium, where rice straw compost at the highest rate (8 t ha-1) exhibit- ed the best response (0.97 c molc kg -1) than those of the other treatments. The maximum amounts of available sulfur, exchangeable calcium and magnesium were obtained from the highest dose of vermicompost and the minimum amounts were attained by the control plot. The trend of increments of all these nutrients were more pronounced with the higher rates of the applied organic amendments indicate that all the applied organic composts are suitable sources for improving nutrient statuses of soils. Pearson correlation and regression analyses also indicate the strong positive relationship between the treatments and nutrient statuses of post-harvest soils (Table VII). The current findings are in consistent with those of Xin et al. (2017). Many steps have been made to improve soil fertility and productivity, according to them. Increased organic input, such as organic manure, compost, and straw integration, are the most effective approaches. Crop straw, a cheap and nutrient-dense material, offers a lot of potential for enhancing soil fertility (Tan et al. 2017). Crop straw, which is high in nutrients and organic elements, can be treated as a natural organic fertilizer and utilized as an alternative to chemical fertilizers, according to the studies of Wang et al. (2017). As a result, straw integration appears to be a potential method for maintaining and restoring soil fertility, the burning issue of present day. Because, mineral elements are required for the healthy growth and development of both plants and humans. The plant roots take up the mineral nutrients from soil and transported them to the edible parts for human consumption through various transporters. For human health, an ideal future crop should be rich in essential mineral elements but with less toxic elements in the edible parts. Still, it is estimat- ed that nearly 2 billion people are suffering from deficiency of nutrients because of low availability of mineral elements in soil and/or low accumulation/bioavailability of mineral elements in edible parts (Graham et al. 2012). This so-called hidden hunger is an especially serious health problem for people subsisting on cereal-based diets because cereals such as rice usually contain a low level of mineral elements as well as low bioavailability (Grebmer et al. 2014; Nakandalage and Seneweera, 2018). On the other hand, rapid urbanization and industrialization cause contamination by toxic elements in many soils used for crop production (Zhao et al. 2010; Clemens and Ma, 2016), which threaten our health throughout the food chain. Therefore, it is extremely important to boost essential nutrients (both density and bioavailability) and reduce toxic elements in edible parts of cereals for human health. Conclusion The present research findings conclude that the locally made organic composts using indigenous organic materi- als had potential to improve soil fertility and provide nutrients for rice production. Significant positive correla- tion between the treatments and mineral nutrients of rice plants confirmed the strong relationship of organic farm- ing for sustainable agriculture. There were significant (p ≤ 0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of amendments under rice production. The nutrition of rice plants grown under field condition was influenced most by the vermi- compost and followed the order of the treatments as rice straw compost > sawdust compost > rice hull compost for the studied variety of rice. These results resemble that the further researches are needed to find out the suitable doses and types of the amendments. However, the applied organ- ic fertilizers were found to have responses on the nutri- tional statuses of rice shoot and post-harvest soils and these might be effective for the nutritional balance of the rice variety and ultimately will be helpful for country’s penniless people to combat their existing and future demand of quality rice. Acknowledgement The study was carried out under a project of the Climate Change Trust Fund (CCTF) titled ‘Assessment of Impacts of Climate Change on Soil Health and Food Security, and Adaptation of Climate-smart Agriculture in Most Adversely Affected Areas of Bangladesh’ through the MoEFCC, Government of the Peoples’ Republic of Bangladesh. The project was implemented in two phases (Phase I: Jan.’17 to Dec.’18, Code 410 DUand Phase II: Jan.’19 to Dec.’22, Code 573 DU) within six years. We are also grateful to the Project staff and relevant officers/staff of the SWED-DU, DU, MoE and MoEFCC of GoB, who performed for the successful completion of the study. References Ahmed S, Alam MJ, Hossain A, Islam AK, Awan TH, Soufan W, Qahtan AA, Okla MK and Sabagh SI (2021), Interactive effect of weeding regimes, rice cultivars, and seeding rates influence the rice-weed competition under dry direct-seeded condition, Sustainability. 13: 317-321. DOI: 10.3390/su13010317 Akter S and Khan HR (2019), Influence of rice hull, rice straw, sawdust and moisture levels on selected proper- ties of post harvested saline soils under variable condi- tions of rice cultivation, National University Journal of Science. 6(1): 61-74. Akter S, Khan HR, Hossain MS, Saha MK and Farzana F (2018), Response of rice grown in saline soil as influenced by the application of agricultural amend- ments and moisture regimes, J biodivers conserv bioresour manag. 4(2): 33-42. DOI: https://doi.org/ 10.3329/jbcbm.v4i2.39845 Ansari AA and Ismail SA (2012), Role of Earthworms in Vermtechnology, J Agric Technol. 8(2): 405-415. https://www.ijat-aatsea.com Arora VK, Singh CB, Sidhu AS and Thind SS (2011), Irriga- tion, tillage and mulching effects on Soybean yield and water productivity in relation to soil texture, Agric Water Manag. 98(4): 563-568. https://- doi.org/10.1016/j.agwat .2010.10.004 BBS (2017), Bangladesh Bureau of Statistics. The Year Book of Agricultural Statistics of Bangladesh. Stat. Div. Minis. Planning, Govt. Peoples Repub. Bangladesh, Dhaka. BBS (2020), Summary Crop Statistics and Crop Indices (2019-2020). Bangladesh Bureau of Statistics Division, Govt. of the People’s Republic of Bangla- desh: Dhaka, Bangladesh. pp 35-37. Chanda GC, Bhunia G and Chakraborty SK (2011), The effect of vermicompost and other fertilizers on cultiva- tion of Tomato plants, J Hortic For. 3: 42-45. http://w- ww.acade mic journals.org/jhf Clemens S and Ma JF (2016), Toxic heavy metal and metal- loid accumulation in crop plants and foods, Annu Rev Plant Biol. 67: 489-512. DOI: 10.1146/annurev-ar- plant-043015-112301 Dinesh R, Suryanarayana MA, Nair AK and Chaudhuri SG (2011), Leguminous cover crop effects on nitrogen mineralization rates and kinetics in soils, J Agron Crop Sci. 187: 161-166. DOI: 10.1046/j.1439-037x. 2001. 00512.x FRG (2012), (Fertilizer Recommendation Guide). Bangladesh Agricultural Research Council (BARC), Dhaka, Bangladesh. Graham RD, Knez M and Welch RM (2012), How much nutritional iron deficiency in humans globally is due to an underlying zinc deficiency, Adv Agron. 1-40. DOI: 10.1016/B978-0-12-394276-0.00001-9 Grebmer BKV, Saltzman A, Birol E, Wiesmann D, Prasai N, YinS, Yohannes Y, Menon P, Thompson J and Sonntag A (2014), 2014 Global Hunger Index: The Challenge of Hidden Hunger (Washington, DC: International Food Policy Research Institute), pp 56. DOI: http://dx- .doi.org/10.2499/9780896299580 Guerrero RD (2010), Vermicompost production and its use for crop production in the Philippines, International Journal of Global Environmental Issues. 10(3/4): 378-383. DOI: 10.1504/IJGENVI.2010.037278 Gurtler JB, Doyle MP, Erickson MC, Jiang X, Millner P and Sharma M (2018), Composting to inactivate food borne pathogens for crop soil application, A review J Food Prot.81: 1821-1837. DOI: 10.4315/0362-028X.- JFP-18-217 Heitkamp F, Raupp J and Ludwig B (2011), Soil organic matter pools and crop yields as affected by the rate of farmyard manure and use of biodynamic preparations in a sandy soil, Organic Agriculture. 11: 111-124. DOI: 10.1007/s13165-011-0010-7 Jahiruddin M and Satter MA (2010), Research priority in agriculture and development of vision document-2030 and beyond. Land and soil resource management. Bangladesh gricultural Research Council. Dhaka. Jeptoo A, Aguyoh JN and Saidi M (2013), Improving Carrot Yield and Quality through the Use of Bio-Slurry Manure, Sustainable Agricultural Research. 2(1): 164-172. DOI: 10.5539/sar.v2n1p164 Nakandalage N and Seneweera S (2018), Micronutrients useefficiency of crop-plants under changing climate. In Plant Micronutrient Use Efficiency, M.A. Hossain, T. Kamiya, D.J. Burritt, L.-S.P. Tran and T. Fujiwara, eds. (London: Academic Press), pp 209-224. Palaniveloo K, Amran MA, Norhashim NA, Mohamad-Fauzi N, Peng-Hui F, Hui-Wen L, Kai-Lin Y, Jiale L, Chian-Yee MG and Jing-Yi L (2020), Food Waste Composting and Microbial Community Structure Profiling, Processes. 8: 723. DOI: org/10.3390/ pr8060723 Partey ST, Thevathasan NV, Zougmoré RB and Preziosi RF (2018), Improving maize production through nitrogen supply from tenrarely-used organic resources in Ghana, Agrofor Syst. 92: 375-387. DOI: 10.1007/ s10457-016-0035-8 Pituello C, Polese R, Morari F and Berti A (2016), Outcomes from a long-term study on crop residue effects on plant yield and nitrogen use efficiency in contrasting soils, Eur J Agron. 77: 179-187. DOI: 10.1016/j. eja.2015.11.027 Somerville PD, Farrell C, May PB and Livesley SJ (2020), Biochar and compost equally improve urban soil physical and biological properties and tree growth, with no added benefit in combination, Sci Total Environ. 706: 135-736. DOI: 10.1016/j.scitotenv. 2019.135736 Tan D, Liu Z, Jiang L, Luo J and Li J (2017), Long-term potash application and wheat straw return reduced soil potassium fixation and affected crop yields in North China, Nutr Cycl Agroecosyst. DOI: 10.1007/s10705- 017-9843-0 Wang W, Sardans J, Wang C, Pan T, Zeng C, Lai D, Bartrons M and Peñuelas J (2017), Straw Application Strategy to Optimize Nutrient Release in a Southeastern China Rice Cropland, Agronomy. 7. DOI: 10.3390/agronomy 7040084 Xin X, Qin S, Zhang J, Zhu A, Yang W and Zhang X (2017), Yield, phosphorus use efficiency and balance response to substituting long-term chemical fertilizer use with organic manure in a wheat-maize system, Field Crop Res. 208: 27-33. DOI: 10.1016/j.fcr.2017.03.011 Yang HS, Xu MM, Koide RT, Liu Q, Dai YJ, Liu L and Bian XM (2016), Effects of ditch-buried straw return on water percolation, nitrogen leaching and crop yields in a rice-wheat rotation system, J Sc. Food Agric. 96: 1141-1149. DOI: 10.1002/jsfa.7196 Zhang P, Chen X, Wei T, Yang Z, Jia Z, Yang B, Han Q and Ren X (2016), Effects of straw incorporation on the soil nutrient contents, enzyme activities, and crop yield in a semiarid region of China, Soil Tillage Res. 160: 65-72. DOI: 10.1016/j.still.2016.02.006 Zhang Y, Liu Y, Zhang G, Guo X, Sun Z and Li T (2018), The Effects of Rice Straw and Biochar Applications on the Microbial Community in a Soil with a History of Continuous Tomato Planting History, Agronomy. 8. DOI: 10.3390/agronomy8050065 Zhao FJ, McGrath SP and Meharg AA (2010), Arsenic as a food chain contaminant: mechanisms of plant uptake and metabolism and mitigation strategies, Annu Rev Plant Biol. 61: 535-559. DOI: 10.1146/annurev-ar- plant-042809-112152 Akter, Khan and Saha 101 However, until now, the use of straw incorporation to increase crop yield is still a matter of argument since studies in different climates and soil types have led to inconclusive results (Pituello et al. 2016). It has been reported that straw incorporation has significant valuable effects on crop yields and soil properties. For instance, straw incorporation can increase crop yields (Yang et al. 2016), soil organic matter and other soil nutrients (Zhang et al. 2018). Straw return can also improve soil physical properties, such as by increasing hydraulic conductivity, decreasing bulk density, and enhancing aggregate forma- tion (Yang et al. 2016). Vermicompost is a nourishing organic fertilizer having high amount of humus, nitrogen 2–3%, phosphorous 1.55–2.25%, potassium 1.85–2.25%, micronutrients, more beneficial for soil microbes like ‘nitrogen fixing bacteria’ and mycorrhizal fungi. Vermicompost has been scientifically proved as miracle plant growth enhancer (Guerrero, 2010). Ansari and Ismail (2012) reported that worms vermicompost contains 7.37 % nitrogen and 19.58% phosphorous as P2O5. Microbial population of N2- fixing bacteria and actinomycetes increases by the application of vermicompost. The amplified microbial activities improve the availability of soil phosphorous and nitrogen. Vermicomposting is an aerobic, biological method and is proficient to convert eco-friendly hummus like organic substances (Chanda et al. 2011). Vermicompost stimulates to influence the microbial activity of soil, increases the availability of oxygen, maintains normal soil temperature, increases soil porosity and infiltration of water, improves nutrient content and increases growth, yield and quality of the plant (Arora et al. 2011). Rice hull and sawdust are also important agricultural amendments. Growth and yield components of rice grown in saline soil were found to be increased significantly (p ≤ 0.05) by the application of rice hull, rice straw and sawdust alone and in combination (Akter et al. 2018). The physico-chemical properties and nutrient status of post-harvest soils were also found to be influenced by the application of these amendments (Akter and Khan, 2019). Composting is a low-cost natural way of recycling and stabilizing organic matter under thermophilic temperature that forms a pathogen-free substrate, beneficial to crops (Gurtler et al. 2018; Somerville et al. 2020). Low-income farmers found it more advantageous to them. Composting was found to be a promising practice that brought organic materials to a certain stage by narrowing down its C:N ratio where nutrients are easily accessible to plants (Palaniveloo et al. 2020). Partey et al. (2018) and Dinesh et al. (2011), had consolidated that biomass needs to decompose for making N available to crops. Thus, composting locally available organic amendments (OAs) is essential for a healthy and sustainable agro-ecosystem in different climatic conditions. Therefore, the objectives of the study were to evaluate the nutrient statuses of post-harvest soils and rice plants grown in Aman season as influenced by the different rates of organic composts applied under field condition. Materials and methods Study site and experimental design In Patuakhali a district of Bangladesh, the field experiment was conducted in Bilbilash of Bauphal Upazila (Map I), which is located between 22°20ʹ00ʺN and 90°20ʹ00ʺE longitude within agro-ecological zone-13 named as Ganges Tidal Floodplain. The climatic condition of this area is usually known as ‘tropical monsoon climate’. The area mainly enjoys three seasons such as rainy, dry and summer season. The experiment was carried out following completely randomized block design with the self-made organic composts, such as, Rice Hull Compost (RHC), Rice Straw Compost (RSC), Sawdust Compost (SDC) and Vermicompost (V) corresponding to the rates of 0, 2, 4 and 8 t ha-1 of each organic compost at Aman season during August to December, 2018. There were 13 plots having individual treatment (Table I) in the experimental area, each unit plot size was 16 m2 (4m×4m) and replications were considered within the plot. Selected properties of potential amendments used and initial soils at field site are presented in the Tables II and III. Transplantation following subsequent protocols Basal doses of N, P2O5, and K2O from urea, TSP, and MoP fertilizers were applied at the rates of 40, 30, and 15 kg ha-1, respectively considering soil amendments and initial contents of the nutrients. During field preparation, the TSP, MoP, and half of the urea were applied in their entirety after being thoroughly mixed with the field soil. The remaining urea was top dressed in two splits, one at the beginning of the rice panicle and another at the active tillering stage. Three seedlings per hill of the BR 25 variety, which were thirty days old and in good health, were transplanted. Row to row and hill to hill distances were each 20 and 22 cm, respectively. No irrigation was required for this study for the growth of rice in this season. Intercultur- al operations such as, weeding, pesticide use, etc. were done as per requirement. Sample collection and analyses Plant samples were collected from each plot just after harvesting. Soil samples were collected from 3 spots as replications of each plot of active root zone (0-15 cm) with the help of an auger. Soil samples were then stored treatment wise in polythene bags with proper labeling. After sun drying and grounding the samples were then passed through 2 mm sieve and stored properly in air tight plastic pots for further analyses. The collected plant samples were sun dried and weighed. After sun drying a portion of the collected plant samples were oven dried at 65⁰C and then grinded and stored in air tight plastic pots for laboratory analyses. All the labora- tory analyses were done following standard methods. Statistical analyses Pearson correlation and regression analyses between treatments and mineral nutrition of rice plants, Analysis of Variance (ANOVA) and Tukey’s Range Test at 5% (p≤ 0.05) level were done for the interpretation of the experi- mental results. Results and discussion Mineral nutrition of rice plants The total nitrogen, phosphorus, potassium, sulfur, calcium and magnesium contents at maturity stage of rice plants grown under field condition were significantly (p≤0.05) influenced by the application of variable indigenous organic amendments (rice hull compost, rice straw compost, sawdust compost and vermicompost) during Aman season (Table IV and Fig.1). Pearson correlation and regression analyses have been performed between the different treatments and mineral nutrition of rice plant tissues (Table V). Significance has been determined based on p values whether they were <0.05 or not. The total nitrogen (r = 0.78***), phosphorus (r = 0.77**), potassium (r = 0.75**), sulfur (r = 0.82***), calcium (r = 0.82***) and magnesium (r = 0.60*) contents of the tested rice plant (BR 25) tissues were signifi- cantly correlated with the applied organic composts and these correlations confirmed that the different sources of organic materials positively influenced the nutrition of rice plant tissues which ultimately regulate the edible part (grain) of the rice crops. According to Graham et al. (2012), people taking cereal based diets still suffering from hidden hunger of nutrients due to low level and low bioavailability of essential elements. The present results demonstrated that the nitro- gen content in rice straw increased with the increased rate of the application of organic composts. The maximum nitrogen contents in the rice plant tissues were recorded at V8 treatment for the tested variety. Among the applied composts, vermicompost (18.63 g kg-1N) ranked first followed by rice straw compost (17.40 g kg-1), sawdust compost (14.57g kg-1) and rice hull compost (13.33 g kg-1), regardless of their doses. Phosphorus contents in rice plant tissues increased with the higher rates of the different composts. The highest (4.42 g kg-1) and lowest (1.10 g kg-1) contents of total phosphorus were recorded in the T12 (V8) and T0 (control) treatments. The rest of the above-men- tioned nutrients were exerted the similar trends as those obtained by the P and N contents by the different organic composts. The nutrition of rice shoots was influenced by the direction of vermicompost > rice straw compost > sawdust compost > rice hull compost for the studied variety of rice grown under field condition. Nutrient status of post-harvest soils Rice production during T. Aman season, the available N contents in the post-harvest soils increased significantly (p ≤ 0.05) by the application of vermicompost, rice hull compost, rice straw compost and sawdust compost (Table VI and Fig. 2). The maximum amount of available N (78.29 mg kg-1) was recorded in T3 (RHC8) treatment, where available nitrogen content increased 85.65% as compared to control plot. At the same dose (8 t ha-1), the sawdust compost treatment ranked second for the available nitrogen content (62.31 mg kg-1) at post-harvest soils followed by RSC8 treatment (60.76 mg kg-1). There were significant (p≤0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of the organic amendments under rice production (Table VI). Soils treated with vermicompost at the rate of 8 t ha-1 was found to have significantly more phosphorus (12.57 mg kg-1) as compared to control plot. The rice straw compost and sawdust compost each at 8 t ha-1 were showed almost similar trends in the increment of available phosphorus contents in post-harvest soils followed by rice hull compost. The other nutrients of post-harvest soils followed the similar trends as that of phosphorus, except for the exchangeable potassium, where rice straw compost at the highest rate (8 t ha-1) exhibit- ed the best response (0.97 c molc kg -1) than those of the other treatments. The maximum amounts of available sulfur, exchangeable calcium and magnesium were obtained from the highest dose of vermicompost and the minimum amounts were attained by the control plot. The trend of increments of all these nutrients were more pronounced with the higher rates of the applied organic amendments indicate that all the applied organic composts are suitable sources for improving nutrient statuses of soils. Pearson correlation and regression analyses also indicate the strong positive relationship between the treatments and nutrient statuses of post-harvest soils (Table VII). The current findings are in consistent with those of Xin et al. (2017). Many steps have been made to improve soil fertility and productivity, according to them. Increased organic input, such as organic manure, compost, and straw integration, are the most effective approaches. Crop straw, a cheap and nutrient-dense material, offers a lot of potential for enhancing soil fertility (Tan et al. 2017). Crop straw, which is high in nutrients and organic elements, can be treated as a natural organic fertilizer and utilized as an alternative to chemical fertilizers, according to the studies of Wang et al. (2017). As a result, straw integration appears to be a potential method for maintaining and restoring soil fertility, the burning issue of present day. Because, mineral elements are required for the healthy growth and development of both plants and humans. The plant roots take up the mineral nutrients from soil and transported them to the edible parts for human consumption through various transporters. For human health, an ideal future crop should be rich in essential mineral elements but with less toxic elements in the edible parts. Still, it is estimat- ed that nearly 2 billion people are suffering from deficiency of nutrients because of low availability of mineral elements in soil and/or low accumulation/bioavailability of mineral elements in edible parts (Graham et al. 2012). This so-called hidden hunger is an especially serious health problem for people subsisting on cereal-based diets because cereals such as rice usually contain a low level of mineral elements as well as low bioavailability (Grebmer et al. 2014; Nakandalage and Seneweera, 2018). On the other hand, rapid urbanization and industrialization cause contamination by toxic elements in many soils used for crop production (Zhao et al. 2010; Clemens and Ma, 2016), which threaten our health throughout the food chain. Therefore, it is extremely important to boost essential nutrients (both density and bioavailability) and reduce toxic elements in edible parts of cereals for human health. Conclusion The present research findings conclude that the locally made organic composts using indigenous organic materi- als had potential to improve soil fertility and provide nutrients for rice production. Significant positive correla- tion between the treatments and mineral nutrients of rice plants confirmed the strong relationship of organic farm- ing for sustainable agriculture. There were significant (p ≤ 0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of amendments under rice production. The nutrition of rice plants grown under field condition was influenced most by the vermi- compost and followed the order of the treatments as rice straw compost > sawdust compost > rice hull compost for the studied variety of rice. These results resemble that the further researches are needed to find out the suitable doses and types of the amendments. However, the applied organ- ic fertilizers were found to have responses on the nutri- tional statuses of rice shoot and post-harvest soils and these might be effective for the nutritional balance of the rice variety and ultimately will be helpful for country’s penniless people to combat their existing and future demand of quality rice. Acknowledgement The study was carried out under a project of the Climate Change Trust Fund (CCTF) titled ‘Assessment of Impacts of Climate Change on Soil Health and Food Security, and Adaptation of Climate-smart Agriculture in Most Adversely Affected Areas of Bangladesh’ through the MoEFCC, Government of the Peoples’ Republic of Bangladesh. The project was implemented in two phases (Phase I: Jan.’17 to Dec.’18, Code 410 DUand Phase II: Jan.’19 to Dec.’22, Code 573 DU) within six years. We are also grateful to the Project staff and relevant officers/staff of the SWED-DU, DU, MoE and MoEFCC of GoB, who performed for the successful completion of the study. References Ahmed S, Alam MJ, Hossain A, Islam AK, Awan TH, Soufan W, Qahtan AA, Okla MK and Sabagh SI (2021), Interactive effect of weeding regimes, rice cultivars, and seeding rates influence the rice-weed competition under dry direct-seeded condition, Sustainability. 13: 317-321. DOI: 10.3390/su13010317 Akter S and Khan HR (2019), Influence of rice hull, rice straw, sawdust and moisture levels on selected proper- ties of post harvested saline soils under variable condi- tions of rice cultivation, National University Journal of Science. 6(1): 61-74. Akter S, Khan HR, Hossain MS, Saha MK and Farzana F (2018), Response of rice grown in saline soil as influenced by the application of agricultural amend- ments and moisture regimes, J biodivers conserv bioresour manag. 4(2): 33-42. DOI: https://doi.org/ 10.3329/jbcbm.v4i2.39845 Ansari AA and Ismail SA (2012), Role of Earthworms in Vermtechnology, J Agric Technol. 8(2): 405-415. https://www.ijat-aatsea.com Arora VK, Singh CB, Sidhu AS and Thind SS (2011), Irriga- tion, tillage and mulching effects on Soybean yield and water productivity in relation to soil texture, Agric Water Manag. 98(4): 563-568. https://- doi.org/10.1016/j.agwat .2010.10.004 BBS (2017), Bangladesh Bureau of Statistics. The Year Book of Agricultural Statistics of Bangladesh. Stat. Div. Minis. Planning, Govt. Peoples Repub. Bangladesh, Dhaka. BBS (2020), Summary Crop Statistics and Crop Indices (2019-2020). Bangladesh Bureau of Statistics Division, Govt. of the People’s Republic of Bangla- desh: Dhaka, Bangladesh. pp 35-37. Chanda GC, Bhunia G and Chakraborty SK (2011), The effect of vermicompost and other fertilizers on cultiva- tion of Tomato plants, J Hortic For. 3: 42-45. http://w- ww.acade mic journals.org/jhf Clemens S and Ma JF (2016), Toxic heavy metal and metal- loid accumulation in crop plants and foods, Annu Rev Plant Biol. 67: 489-512. DOI: 10.1146/annurev-ar- plant-043015-112301 Dinesh R, Suryanarayana MA, Nair AK and Chaudhuri SG (2011), Leguminous cover crop effects on nitrogen mineralization rates and kinetics in soils, J Agron Crop Sci. 187: 161-166. DOI: 10.1046/j.1439-037x. 2001. 00512.x FRG (2012), (Fertilizer Recommendation Guide). Bangladesh Agricultural Research Council (BARC), Dhaka, Bangladesh. Graham RD, Knez M and Welch RM (2012), How much nutritional iron deficiency in humans globally is due to an underlying zinc deficiency, Adv Agron. 1-40. DOI: 10.1016/B978-0-12-394276-0.00001-9 Grebmer BKV, Saltzman A, Birol E, Wiesmann D, Prasai N, YinS, Yohannes Y, Menon P, Thompson J and Sonntag A (2014), 2014 Global Hunger Index: The Challenge of Hidden Hunger (Washington, DC: International Food Policy Research Institute), pp 56. DOI: http://dx- .doi.org/10.2499/9780896299580 Guerrero RD (2010), Vermicompost production and its use for crop production in the Philippines, International Journal of Global Environmental Issues. 10(3/4): 378-383. DOI: 10.1504/IJGENVI.2010.037278 Gurtler JB, Doyle MP, Erickson MC, Jiang X, Millner P and Sharma M (2018), Composting to inactivate food borne pathogens for crop soil application, A review J Food Prot.81: 1821-1837. DOI: 10.4315/0362-028X.- JFP-18-217 Heitkamp F, Raupp J and Ludwig B (2011), Soil organic matter pools and crop yields as affected by the rate of farmyard manure and use of biodynamic preparations in a sandy soil, Organic Agriculture. 11: 111-124. DOI: 10.1007/s13165-011-0010-7 Jahiruddin M and Satter MA (2010), Research priority in agriculture and development of vision document-2030 and beyond. Land and soil resource management. Bangladesh gricultural Research Council. Dhaka. Jeptoo A, Aguyoh JN and Saidi M (2013), Improving Carrot Yield and Quality through the Use of Bio-Slurry Manure, Sustainable Agricultural Research. 2(1): 164-172. DOI: 10.5539/sar.v2n1p164 Nakandalage N and Seneweera S (2018), Micronutrients useefficiency of crop-plants under changing climate. In Plant Micronutrient Use Efficiency, M.A. Hossain, T. Kamiya, D.J. Burritt, L.-S.P. Tran and T. Fujiwara, eds. (London: Academic Press), pp 209-224. Palaniveloo K, Amran MA, Norhashim NA, Mohamad-Fauzi N, Peng-Hui F, Hui-Wen L, Kai-Lin Y, Jiale L, Chian-Yee MG and Jing-Yi L (2020), Food Waste Composting and Microbial Community Structure Profiling, Processes. 8: 723. DOI: org/10.3390/ pr8060723 Partey ST, Thevathasan NV, Zougmoré RB and Preziosi RF (2018), Improving maize production through nitrogen supply from tenrarely-used organic resources in Ghana, Agrofor Syst. 92: 375-387. DOI: 10.1007/ s10457-016-0035-8 Pituello C, Polese R, Morari F and Berti A (2016), Outcomes from a long-term study on crop residue effects on plant yield and nitrogen use efficiency in contrasting soils, Eur J Agron. 77: 179-187. DOI: 10.1016/j. eja.2015.11.027 Somerville PD, Farrell C, May PB and Livesley SJ (2020), Biochar and compost equally improve urban soil physical and biological properties and tree growth, with no added benefit in combination, Sci Total Environ. 706: 135-736. DOI: 10.1016/j.scitotenv. 2019.135736 Tan D, Liu Z, Jiang L, Luo J and Li J (2017), Long-term potash application and wheat straw return reduced soil potassium fixation and affected crop yields in North China, Nutr Cycl Agroecosyst. DOI: 10.1007/s10705- 017-9843-0 Wang W, Sardans J, Wang C, Pan T, Zeng C, Lai D, Bartrons M and Peñuelas J (2017), Straw Application Strategy to Optimize Nutrient Release in a Southeastern China Rice Cropland, Agronomy. 7. DOI: 10.3390/agronomy 7040084 Xin X, Qin S, Zhang J, Zhu A, Yang W and Zhang X (2017), Yield, phosphorus use efficiency and balance response to substituting long-term chemical fertilizer use with organic manure in a wheat-maize system, Field Crop Res. 208: 27-33. DOI: 10.1016/j.fcr.2017.03.011 Yang HS, Xu MM, Koide RT, Liu Q, Dai YJ, Liu L and Bian XM (2016), Effects of ditch-buried straw return on water percolation, nitrogen leaching and crop yields in a rice-wheat rotation system, J Sc. Food Agric. 96: 1141-1149. DOI: 10.1002/jsfa.7196 Zhang P, Chen X, Wei T, Yang Z, Jia Z, Yang B, Han Q and Ren X (2016), Effects of straw incorporation on the soil nutrient contents, enzyme activities, and crop yield in a semiarid region of China, Soil Tillage Res. 160: 65-72. DOI: 10.1016/j.still.2016.02.006 Zhang Y, Liu Y, Zhang G, Guo X, Sun Z and Li T (2018), The Effects of Rice Straw and Biochar Applications on the Microbial Community in a Soil with a History of Continuous Tomato Planting History, Agronomy. 8. DOI: 10.3390/agronomy8050065 Zhao FJ, McGrath SP and Meharg AA (2010), Arsenic as a food chain contaminant: mechanisms of plant uptake and metabolism and mitigation strategies, Annu Rev Plant Biol. 61: 535-559. DOI: 10.1146/annurev-ar- plant-042809-112152 Map I. Location map of the study site #A = Barishal division in Bangladesh map; B = Patuakhali district in Barishal divisional map and C = Bauphal upazila (study site) in Patuakhali district map. Table II. Nutrient compositions of different organic amendments used in the field experiment Nutrient element (%) Organic composts RHC RSC SDC V Org. C 11.37 20.17 13.28 16.15 Total N 0.57 1.07 1.02 1.05 Total P 0.15 0.36 0.31 0.72 Total K 0.14 0.43 0.23 0.79 Total S 0.23 0.29 0.22 0.28 Total Ca 0.08 0.21 0.14 0.24 Total Mg 0.07 0.18 0.09 0.15 Table I. Description of the treatments used for the experiment Treatment No. Description No. Description T0 = Control No amendments were made T7 = SDC2 Sawdust compost @ 2 t ha-1 T1 = RHC2 Rice hull compost @ 2 t ha-1 T8 = SDC4 Sawdust compost @ 4 t ha-1 T2 = RHC4 Rice hull compost @ 4 t ha-1 T9 = SDC8 Sawdust compost @ 8 t ha-1 T3 = RHC8 Rice hull compost @ 8 t ha-1 T10 = V2 Vermicompost @ 2 t ha-1 T4 = RSC2 Rice straw compost @ 2 t ha-1 T11 = V4 Vermicompost @ 4 t ha-1 T5 = RSC4 Rice straw compost @ 4 t ha-1 T12 = V8 Vermicompost @ 8 t ha-1 T6 = RSC8 Rice straw compost @ 8 t ha-1 Mineral nutrition of rice and post-harvest soils influenced by self-made organic composts 58(2) 2023102 However, until now, the use of straw incorporation to increase crop yield is still a matter of argument since studies in different climates and soil types have led to inconclusive results (Pituello et al. 2016). It has been reported that straw incorporation has significant valuable effects on crop yields and soil properties. For instance, straw incorporation can increase crop yields (Yang et al. 2016), soil organic matter and other soil nutrients (Zhang et al. 2018). Straw return can also improve soil physical properties, such as by increasing hydraulic conductivity, decreasing bulk density, and enhancing aggregate forma- tion (Yang et al. 2016). Vermicompost is a nourishing organic fertilizer having high amount of humus, nitrogen 2–3%, phosphorous 1.55–2.25%, potassium 1.85–2.25%, micronutrients, more beneficial for soil microbes like ‘nitrogen fixing bacteria’ and mycorrhizal fungi. Vermicompost has been scientifically proved as miracle plant growth enhancer (Guerrero, 2010). Ansari and Ismail (2012) reported that worms vermicompost contains 7.37 % nitrogen and 19.58% phosphorous as P2O5. Microbial population of N2- fixing bacteria and actinomycetes increases by the application of vermicompost. The amplified microbial activities improve the availability of soil phosphorous and nitrogen. Vermicomposting is an aerobic, biological method and is proficient to convert eco-friendly hummus like organic substances (Chanda et al. 2011). Vermicompost stimulates to influence the microbial activity of soil, increases the availability of oxygen, maintains normal soil temperature, increases soil porosity and infiltration of water, improves nutrient content and increases growth, yield and quality of the plant (Arora et al. 2011). Rice hull and sawdust are also important agricultural amendments. Growth and yield components of rice grown in saline soil were found to be increased significantly (p ≤ 0.05) by the application of rice hull, rice straw and sawdust alone and in combination (Akter et al. 2018). The physico-chemical properties and nutrient status of post-harvest soils were also found to be influenced by the application of these amendments (Akter and Khan, 2019). Composting is a low-cost natural way of recycling and stabilizing organic matter under thermophilic temperature that forms a pathogen-free substrate, beneficial to crops (Gurtler et al. 2018; Somerville et al. 2020). Low-income farmers found it more advantageous to them. Composting was found to be a promising practice that brought organic materials to a certain stage by narrowing down its C:N ratio where nutrients are easily accessible to plants (Palaniveloo et al. 2020). Partey et al. (2018) and Dinesh et al. (2011), had consolidated that biomass needs to decompose for making N available to crops. Thus, composting locally available organic amendments (OAs) is essential for a healthy and sustainable agro-ecosystem in different climatic conditions. Therefore, the objectives of the study were to evaluate the nutrient statuses of post-harvest soils and rice plants grown in Aman season as influenced by the different rates of organic composts applied under field condition. Materials and methods Study site and experimental design In Patuakhali a district of Bangladesh, the field experiment was conducted in Bilbilash of Bauphal Upazila (Map I), which is located between 22°20ʹ00ʺN and 90°20ʹ00ʺE longitude within agro-ecological zone-13 named as Ganges Tidal Floodplain. The climatic condition of this area is usually known as ‘tropical monsoon climate’. The area mainly enjoys three seasons such as rainy, dry and summer season. The experiment was carried out following completely randomized block design with the self-made organic composts, such as, Rice Hull Compost (RHC), Rice Straw Compost (RSC), Sawdust Compost (SDC) and Vermicompost (V) corresponding to the rates of 0, 2, 4 and 8 t ha-1 of each organic compost at Aman season during August to December, 2018. There were 13 plots having individual treatment (Table I) in the experimental area, each unit plot size was 16 m2 (4m×4m) and replications were considered within the plot. Selected properties of potential amendments used and initial soils at field site are presented in the Tables II and III. Transplantation following subsequent protocols Basal doses of N, P2O5, and K2O from urea, TSP, and MoP fertilizers were applied at the rates of 40, 30, and 15 kg ha-1, respectively considering soil amendments and initial contents of the nutrients. During field preparation, the TSP, MoP, and half of the urea were applied in their entirety after being thoroughly mixed with the field soil. The remaining urea was top dressed in two splits, one at the beginning of the rice panicle and another at the active tillering stage. Three seedlings per hill of the BR 25 variety, which were thirty days old and in good health, were transplanted. Row to row and hill to hill distances were each 20 and 22 cm, respectively. No irrigation was required for this study for the growth of rice in this season. Intercultur- al operations such as, weeding, pesticide use, etc. were done as per requirement. Sample collection and analyses Plant samples were collected from each plot just after harvesting. Soil samples were collected from 3 spots as replications of each plot of active root zone (0-15 cm) with the help of an auger. Soil samples were then stored treatment wise in polythene bags with proper labeling. After sun drying and grounding the samples were then passed through 2 mm sieve and stored properly in air tight plastic pots for further analyses. The collected plant samples were sun dried and weighed. After sun drying a portion of the collected plant samples were oven dried at 65⁰C and then grinded and stored in air tight plastic pots for laboratory analyses. All the labora- tory analyses were done following standard methods. Statistical analyses Pearson correlation and regression analyses between treatments and mineral nutrition of rice plants, Analysis of Variance (ANOVA) and Tukey’s Range Test at 5% (p≤ 0.05) level were done for the interpretation of the experi- mental results. Results and discussion Mineral nutrition of rice plants The total nitrogen, phosphorus, potassium, sulfur, calcium and magnesium contents at maturity stage of rice plants grown under field condition were significantly (p≤0.05) influenced by the application of variable indigenous organic amendments (rice hull compost, rice straw compost, sawdust compost and vermicompost) during Aman season (Table IV and Fig.1). Pearson correlation and regression analyses have been performed between the different treatments and mineral nutrition of rice plant tissues (Table V). Significance has been determined based on p values whether they were <0.05 or not. The total nitrogen (r = 0.78***), phosphorus (r = 0.77**), potassium (r = 0.75**), sulfur (r = 0.82***), calcium (r = 0.82***) and magnesium (r = 0.60*) contents of the tested rice plant (BR 25) tissues were signifi- cantly correlated with the applied organic composts and these correlations confirmed that the different sources of organic materials positively influenced the nutrition of rice plant tissues which ultimately regulate the edible part (grain) of the rice crops. According to Graham et al. (2012), people taking cereal based diets still suffering from hidden hunger of nutrients due to low level and low bioavailability of essential elements. The present results demonstrated that the nitro- gen content in rice straw increased with the increased rate of the application of organic composts. The maximum nitrogen contents in the rice plant tissues were recorded at V8 treatment for the tested variety. Among the applied composts, vermicompost (18.63 g kg-1N) ranked first followed by rice straw compost (17.40 g kg-1), sawdust compost (14.57g kg-1) and rice hull compost (13.33 g kg-1), regardless of their doses. Phosphorus contents in rice plant tissues increased with the higher rates of the different composts. The highest (4.42 g kg-1) and lowest (1.10 g kg-1) contents of total phosphorus were recorded in the T12 (V8) and T0 (control) treatments. The rest of the above-men- tioned nutrients were exerted the similar trends as those obtained by the P and N contents by the different organic composts. The nutrition of rice shoots was influenced by the direction of vermicompost > rice straw compost > sawdust compost > rice hull compost for the studied variety of rice grown under field condition. Nutrient status of post-harvest soils Rice production during T. Aman season, the available N contents in the post-harvest soils increased significantly (p ≤ 0.05) by the application of vermicompost, rice hull compost, rice straw compost and sawdust compost (Table VI and Fig. 2). The maximum amount of available N (78.29 mg kg-1) was recorded in T3 (RHC8) treatment, where available nitrogen content increased 85.65% as compared to control plot. At the same dose (8 t ha-1), the sawdust compost treatment ranked second for the available nitrogen content (62.31 mg kg-1) at post-harvest soils followed by RSC8 treatment (60.76 mg kg-1). There were significant (p≤0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of the organic amendments under rice production (Table VI). Soils treated with vermicompost at the rate of 8 t ha-1 was found to have significantly more phosphorus (12.57 mg kg-1) as compared to control plot. The rice straw compost and sawdust compost each at 8 t ha-1 were showed almost similar trends in the increment of available phosphorus contents in post-harvest soils followed by rice hull compost. The other nutrients of post-harvest soils followed the similar trends as that of phosphorus, except for the exchangeable potassium, where rice straw compost at the highest rate (8 t ha-1) exhibit- ed the best response (0.97 c molc kg -1) than those of the other treatments. The maximum amounts of available sulfur, exchangeable calcium and magnesium were obtained from the highest dose of vermicompost and the minimum amounts were attained by the control plot. The trend of increments of all these nutrients were more pronounced with the higher rates of the applied organic amendments indicate that all the applied organic composts are suitable sources for improving nutrient statuses of soils. Pearson correlation and regression analyses also indicate the strong positive relationship between the treatments and nutrient statuses of post-harvest soils (Table VII). The current findings are in consistent with those of Xin et al. (2017). Many steps have been made to improve soil fertility and productivity, according to them. Increased organic input, such as organic manure, compost, and straw integration, are the most effective approaches. Crop straw, a cheap and nutrient-dense material, offers a lot of potential for enhancing soil fertility (Tan et al. 2017). Crop straw, which is high in nutrients and organic elements, can be treated as a natural organic fertilizer and utilized as an alternative to chemical fertilizers, according to the studies of Wang et al. (2017). As a result, straw integration appears to be a potential method for maintaining and restoring soil fertility, the burning issue of present day. Because, mineral elements are required for the healthy growth and development of both plants and humans. The plant roots take up the mineral nutrients from soil and transported them to the edible parts for human consumption through various transporters. For human health, an ideal future crop should be rich in essential mineral elements but with less toxic elements in the edible parts. Still, it is estimat- ed that nearly 2 billion people are suffering from deficiency of nutrients because of low availability of mineral elements in soil and/or low accumulation/bioavailability of mineral elements in edible parts (Graham et al. 2012). This so-called hidden hunger is an especially serious health problem for people subsisting on cereal-based diets because cereals such as rice usually contain a low level of mineral elements as well as low bioavailability (Grebmer et al. 2014; Nakandalage and Seneweera, 2018). On the other hand, rapid urbanization and industrialization cause contamination by toxic elements in many soils used for crop production (Zhao et al. 2010; Clemens and Ma, 2016), which threaten our health throughout the food chain. Therefore, it is extremely important to boost essential nutrients (both density and bioavailability) and reduce toxic elements in edible parts of cereals for human health. Conclusion The present research findings conclude that the locally made organic composts using indigenous organic materi- als had potential to improve soil fertility and provide nutrients for rice production. Significant positive correla- tion between the treatments and mineral nutrients of rice plants confirmed the strong relationship of organic farm- ing for sustainable agriculture. There were significant (p ≤ 0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of amendments under rice production. The nutrition of rice plants grown under field condition was influenced most by the vermi- compost and followed the order of the treatments as rice straw compost > sawdust compost > rice hull compost for the studied variety of rice. These results resemble that the further researches are needed to find out the suitable doses and types of the amendments. However, the applied organ- ic fertilizers were found to have responses on the nutri- tional statuses of rice shoot and post-harvest soils and these might be effective for the nutritional balance of the rice variety and ultimately will be helpful for country’s penniless people to combat their existing and future demand of quality rice. Acknowledgement The study was carried out under a project of the Climate Change Trust Fund (CCTF) titled ‘Assessment of Impacts of Climate Change on Soil Health and Food Security, and Adaptation of Climate-smart Agriculture in Most Adversely Affected Areas of Bangladesh’ through the MoEFCC, Government of the Peoples’ Republic of Bangladesh. The project was implemented in two phases (Phase I: Jan.’17 to Dec.’18, Code 410 DUand Phase II: Jan.’19 to Dec.’22, Code 573 DU) within six years. We are also grateful to the Project staff and relevant officers/staff of the SWED-DU, DU, MoE and MoEFCC of GoB, who performed for the successful completion of the study. References Ahmed S, Alam MJ, Hossain A, Islam AK, Awan TH, Soufan W, Qahtan AA, Okla MK and Sabagh SI (2021), Interactive effect of weeding regimes, rice cultivars, and seeding rates influence the rice-weed competition under dry direct-seeded condition, Sustainability. 13: 317-321. DOI: 10.3390/su13010317 Akter S and Khan HR (2019), Influence of rice hull, rice straw, sawdust and moisture levels on selected proper- ties of post harvested saline soils under variable condi- tions of rice cultivation, National University Journal of Science. 6(1): 61-74. Akter S, Khan HR, Hossain MS, Saha MK and Farzana F (2018), Response of rice grown in saline soil as influenced by the application of agricultural amend- ments and moisture regimes, J biodivers conserv bioresour manag. 4(2): 33-42. DOI: https://doi.org/ 10.3329/jbcbm.v4i2.39845 Ansari AA and Ismail SA (2012), Role of Earthworms in Vermtechnology, J Agric Technol. 8(2): 405-415. https://www.ijat-aatsea.com Arora VK, Singh CB, Sidhu AS and Thind SS (2011), Irriga- tion, tillage and mulching effects on Soybean yield and water productivity in relation to soil texture, Agric Water Manag. 98(4): 563-568. https://- doi.org/10.1016/j.agwat .2010.10.004 BBS (2017), Bangladesh Bureau of Statistics. The Year Book of Agricultural Statistics of Bangladesh. Stat. Div. Minis. Planning, Govt. Peoples Repub. Bangladesh, Dhaka. BBS (2020), Summary Crop Statistics and Crop Indices (2019-2020). Bangladesh Bureau of Statistics Division, Govt. of the People’s Republic of Bangla- desh: Dhaka, Bangladesh. pp 35-37. Chanda GC, Bhunia G and Chakraborty SK (2011), The effect of vermicompost and other fertilizers on cultiva- tion of Tomato plants, J Hortic For. 3: 42-45. http://w- ww.acade mic journals.org/jhf Clemens S and Ma JF (2016), Toxic heavy metal and metal- loid accumulation in crop plants and foods, Annu Rev Plant Biol. 67: 489-512. DOI: 10.1146/annurev-ar- plant-043015-112301 Dinesh R, Suryanarayana MA, Nair AK and Chaudhuri SG (2011), Leguminous cover crop effects on nitrogen mineralization rates and kinetics in soils, J Agron Crop Sci. 187: 161-166. DOI: 10.1046/j.1439-037x. 2001. 00512.x FRG (2012), (Fertilizer Recommendation Guide). Bangladesh Agricultural Research Council (BARC), Dhaka, Bangladesh. Graham RD, Knez M and Welch RM (2012), How much nutritional iron deficiency in humans globally is due to an underlying zinc deficiency, Adv Agron. 1-40. DOI: 10.1016/B978-0-12-394276-0.00001-9 Grebmer BKV, Saltzman A, Birol E, Wiesmann D, Prasai N, YinS, Yohannes Y, Menon P, Thompson J and Sonntag A (2014), 2014 Global Hunger Index: The Challenge of Hidden Hunger (Washington, DC: International Food Policy Research Institute), pp 56. DOI: http://dx- .doi.org/10.2499/9780896299580 Guerrero RD (2010), Vermicompost production and its use for crop production in the Philippines, International Journal of Global Environmental Issues. 10(3/4): 378-383. DOI: 10.1504/IJGENVI.2010.037278 Gurtler JB, Doyle MP, Erickson MC, Jiang X, Millner P and Sharma M (2018), Composting to inactivate food borne pathogens for crop soil application, A review J Food Prot.81: 1821-1837. DOI: 10.4315/0362-028X.- JFP-18-217 Heitkamp F, Raupp J and Ludwig B (2011), Soil organic matter pools and crop yields as affected by the rate of farmyard manure and use of biodynamic preparations in a sandy soil, Organic Agriculture. 11: 111-124. DOI: 10.1007/s13165-011-0010-7 Jahiruddin M and Satter MA (2010), Research priority in agriculture and development of vision document-2030 and beyond. Land and soil resource management. Bangladesh gricultural Research Council. Dhaka. Jeptoo A, Aguyoh JN and Saidi M (2013), Improving Carrot Yield and Quality through the Use of Bio-Slurry Manure, Sustainable Agricultural Research. 2(1): 164-172. DOI: 10.5539/sar.v2n1p164 Nakandalage N and Seneweera S (2018), Micronutrients useefficiency of crop-plants under changing climate. In Plant Micronutrient Use Efficiency, M.A. Hossain, T. Kamiya, D.J. Burritt, L.-S.P. Tran and T. Fujiwara, eds. (London: Academic Press), pp 209-224. Palaniveloo K, Amran MA, Norhashim NA, Mohamad-Fauzi N, Peng-Hui F, Hui-Wen L, Kai-Lin Y, Jiale L, Chian-Yee MG and Jing-Yi L (2020), Food Waste Composting and Microbial Community Structure Profiling, Processes. 8: 723. DOI: org/10.3390/ pr8060723 Partey ST, Thevathasan NV, Zougmoré RB and Preziosi RF (2018), Improving maize production through nitrogen supply from tenrarely-used organic resources in Ghana, Agrofor Syst. 92: 375-387. DOI: 10.1007/ s10457-016-0035-8 Pituello C, Polese R, Morari F and Berti A (2016), Outcomes from a long-term study on crop residue effects on plant yield and nitrogen use efficiency in contrasting soils, Eur J Agron. 77: 179-187. DOI: 10.1016/j. eja.2015.11.027 Somerville PD, Farrell C, May PB and Livesley SJ (2020), Biochar and compost equally improve urban soil physical and biological properties and tree growth, with no added benefit in combination, Sci Total Environ. 706: 135-736. DOI: 10.1016/j.scitotenv. 2019.135736 Tan D, Liu Z, Jiang L, Luo J and Li J (2017), Long-term potash application and wheat straw return reduced soil potassium fixation and affected crop yields in North China, Nutr Cycl Agroecosyst. DOI: 10.1007/s10705- 017-9843-0 Wang W, Sardans J, Wang C, Pan T, Zeng C, Lai D, Bartrons M and Peñuelas J (2017), Straw Application Strategy to Optimize Nutrient Release in a Southeastern China Rice Cropland, Agronomy. 7. DOI: 10.3390/agronomy 7040084 Xin X, Qin S, Zhang J, Zhu A, Yang W and Zhang X (2017), Yield, phosphorus use efficiency and balance response to substituting long-term chemical fertilizer use with organic manure in a wheat-maize system, Field Crop Res. 208: 27-33. DOI: 10.1016/j.fcr.2017.03.011 Yang HS, Xu MM, Koide RT, Liu Q, Dai YJ, Liu L and Bian XM (2016), Effects of ditch-buried straw return on water percolation, nitrogen leaching and crop yields in a rice-wheat rotation system, J Sc. Food Agric. 96: 1141-1149. DOI: 10.1002/jsfa.7196 Zhang P, Chen X, Wei T, Yang Z, Jia Z, Yang B, Han Q and Ren X (2016), Effects of straw incorporation on the soil nutrient contents, enzyme activities, and crop yield in a semiarid region of China, Soil Tillage Res. 160: 65-72. DOI: 10.1016/j.still.2016.02.006 Zhang Y, Liu Y, Zhang G, Guo X, Sun Z and Li T (2018), The Effects of Rice Straw and Biochar Applications on the Microbial Community in a Soil with a History of Continuous Tomato Planting History, Agronomy. 8. DOI: 10.3390/agronomy8050065 Zhao FJ, McGrath SP and Meharg AA (2010), Arsenic as a food chain contaminant: mechanisms of plant uptake and metabolism and mitigation strategies, Annu Rev Plant Biol. 61: 535-559. DOI: 10.1146/annurev-ar- plant-042809-112152 Table III. Selected properties of initial soil (on oven dry basis: 0-15 cm) used in the field experiment Properties Values A. Physical Particle density (g cm-3) 2.53 Bulk density (g cm-3) 1.25 Porosity (%) 50.21 Moisture content (%) 3.15 Particle size distribution Sand (%) 5.67 Silt (%) 57.47 Clay (%) 36.86 Textural class B. Chemical pH 4.57 EC (Saturation extract, 1:5; dS m-1) 0.21 Organic matter (%) Total nitrogen (g kg-1) 1.56 0.54 Available nitrogen (mg kg-1) 63.07 Available phosphorus (mg kg-1) 7.21 Available sulfur (mg kg-1) 19.18 Exchangeable Cations (c molc kg -1): Potassium (K+) 0.21 Calcium (Ca2+) 5.41 Magnesium (Mg2+) 3.88 Cation Exchange Capacity (c molckg -1) 12.87 Akter, Khan and Saha 103 However, until now, the use of straw incorporation to increase crop yield is still a matter of argument since studies in different climates and soil types have led to inconclusive results (Pituello et al. 2016). It has been reported that straw incorporation has significant valuable effects on crop yields and soil properties. For instance, straw incorporation can increase crop yields (Yang et al. 2016), soil organic matter and other soil nutrients (Zhang et al. 2018). Straw return can also improve soil physical properties, such as by increasing hydraulic conductivity, decreasing bulk density, and enhancing aggregate forma- tion (Yang et al. 2016). Vermicompost is a nourishing organic fertilizer having high amount of humus, nitrogen 2–3%, phosphorous 1.55–2.25%, potassium 1.85–2.25%, micronutrients, more beneficial for soil microbes like ‘nitrogen fixing bacteria’ and mycorrhizal fungi. Vermicompost has been scientifically proved as miracle plant growth enhancer (Guerrero, 2010). Ansari and Ismail (2012) reported that worms vermicompost contains 7.37 % nitrogen and 19.58% phosphorous as P2O5. Microbial population of N2- fixing bacteria and actinomycetes increases by the application of vermicompost. The amplified microbial activities improve the availability of soil phosphorous and nitrogen. Vermicomposting is an aerobic, biological method and is proficient to convert eco-friendly hummus like organic substances (Chanda et al. 2011). Vermicompost stimulates to influence the microbial activity of soil, increases the availability of oxygen, maintains normal soil temperature, increases soil porosity and infiltration of water, improves nutrient content and increases growth, yield and quality of the plant (Arora et al. 2011). Rice hull and sawdust are also important agricultural amendments. Growth and yield components of rice grown in saline soil were found to be increased significantly (p ≤ 0.05) by the application of rice hull, rice straw and sawdust alone and in combination (Akter et al. 2018). The physico-chemical properties and nutrient status of post-harvest soils were also found to be influenced by the application of these amendments (Akter and Khan, 2019). Composting is a low-cost natural way of recycling and stabilizing organic matter under thermophilic temperature that forms a pathogen-free substrate, beneficial to crops (Gurtler et al. 2018; Somerville et al. 2020). Low-income farmers found it more advantageous to them. Composting was found to be a promising practice that brought organic materials to a certain stage by narrowing down its C:N ratio where nutrients are easily accessible to plants (Palaniveloo et al. 2020). Partey et al. (2018) and Dinesh et al. (2011), had consolidated that biomass needs to decompose for making N available to crops. Thus, composting locally available organic amendments (OAs) is essential for a healthy and sustainable agro-ecosystem in different climatic conditions. Therefore, the objectives of the study were to evaluate the nutrient statuses of post-harvest soils and rice plants grown in Aman season as influenced by the different rates of organic composts applied under field condition. Materials and methods Study site and experimental design In Patuakhali a district of Bangladesh, the field experiment was conducted in Bilbilash of Bauphal Upazila (Map I), which is located between 22°20ʹ00ʺN and 90°20ʹ00ʺE longitude within agro-ecological zone-13 named as Ganges Tidal Floodplain. The climatic condition of this area is usually known as ‘tropical monsoon climate’. The area mainly enjoys three seasons such as rainy, dry and summer season. The experiment was carried out following completely randomized block design with the self-made organic composts, such as, Rice Hull Compost (RHC), Rice Straw Compost (RSC), Sawdust Compost (SDC) and Vermicompost (V) corresponding to the rates of 0, 2, 4 and 8 t ha-1 of each organic compost at Aman season during August to December, 2018. There were 13 plots having individual treatment (Table I) in the experimental area, each unit plot size was 16 m2 (4m×4m) and replications were considered within the plot. Selected properties of potential amendments used and initial soils at field site are presented in the Tables II and III. Transplantation following subsequent protocols Basal doses of N, P2O5, and K2O from urea, TSP, and MoP fertilizers were applied at the rates of 40, 30, and 15 kg ha-1, respectively considering soil amendments and initial contents of the nutrients. During field preparation, the TSP, MoP, and half of the urea were applied in their entirety after being thoroughly mixed with the field soil. The remaining urea was top dressed in two splits, one at the beginning of the rice panicle and another at the active tillering stage. Three seedlings per hill of the BR 25 variety, which were thirty days old and in good health, were transplanted. Row to row and hill to hill distances were each 20 and 22 cm, respectively. No irrigation was required for this study for the growth of rice in this season. Intercultur- al operations such as, weeding, pesticide use, etc. were done as per requirement. Sample collection and analyses Plant samples were collected from each plot just after harvesting. Soil samples were collected from 3 spots as replications of each plot of active root zone (0-15 cm) with the help of an auger. Soil samples were then stored treatment wise in polythene bags with proper labeling. After sun drying and grounding the samples were then passed through 2 mm sieve and stored properly in air tight plastic pots for further analyses. The collected plant samples were sun dried and weighed. After sun drying a portion of the collected plant samples were oven dried at 65⁰C and then grinded and stored in air tight plastic pots for laboratory analyses. All the labora- tory analyses were done following standard methods. Statistical analyses Pearson correlation and regression analyses between treatments and mineral nutrition of rice plants, Analysis of Variance (ANOVA) and Tukey’s Range Test at 5% (p≤ 0.05) level were done for the interpretation of the experi- mental results. Results and discussion Mineral nutrition of rice plants The total nitrogen, phosphorus, potassium, sulfur, calcium and magnesium contents at maturity stage of rice plants grown under field condition were significantly (p≤0.05) influenced by the application of variable indigenous organic amendments (rice hull compost, rice straw compost, sawdust compost and vermicompost) during Aman season (Table IV and Fig.1). Pearson correlation and regression analyses have been performed between the different treatments and mineral nutrition of rice plant tissues (Table V). Significance has been determined based on p values whether they were <0.05 or not. The total nitrogen (r = 0.78***), phosphorus (r = 0.77**), potassium (r = 0.75**), sulfur (r = 0.82***), calcium (r = 0.82***) and magnesium (r = 0.60*) contents of the tested rice plant (BR 25) tissues were signifi- cantly correlated with the applied organic composts and these correlations confirmed that the different sources of organic materials positively influenced the nutrition of rice plant tissues which ultimately regulate the edible part (grain) of the rice crops. According to Graham et al. (2012), people taking cereal based diets still suffering from hidden hunger of nutrients due to low level and low bioavailability of essential elements. The present results demonstrated that the nitro- gen content in rice straw increased with the increased rate of the application of organic composts. The maximum nitrogen contents in the rice plant tissues were recorded at V8 treatment for the tested variety. Among the applied composts, vermicompost (18.63 g kg-1N) ranked first followed by rice straw compost (17.40 g kg-1), sawdust compost (14.57g kg-1) and rice hull compost (13.33 g kg-1), regardless of their doses. Phosphorus contents in rice plant tissues increased with the higher rates of the different composts. The highest (4.42 g kg-1) and lowest (1.10 g kg-1) contents of total phosphorus were recorded in the T12 (V8) and T0 (control) treatments. The rest of the above-men- tioned nutrients were exerted the similar trends as those obtained by the P and N contents by the different organic composts. The nutrition of rice shoots was influenced by the direction of vermicompost > rice straw compost > sawdust compost > rice hull compost for the studied variety of rice grown under field condition. Nutrient status of post-harvest soils Rice production during T. Aman season, the available N contents in the post-harvest soils increased significantly (p ≤ 0.05) by the application of vermicompost, rice hull compost, rice straw compost and sawdust compost (Table VI and Fig. 2). The maximum amount of available N (78.29 mg kg-1) was recorded in T3 (RHC8) treatment, where available nitrogen content increased 85.65% as compared to control plot. At the same dose (8 t ha-1), the sawdust compost treatment ranked second for the available nitrogen content (62.31 mg kg-1) at post-harvest soils followed by RSC8 treatment (60.76 mg kg-1). There were significant (p≤0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of the organic amendments under rice production (Table VI). Soils treated with vermicompost at the rate of 8 t ha-1 was found to have significantly more phosphorus (12.57 mg kg-1) as compared to control plot. The rice straw compost and sawdust compost each at 8 t ha-1 were showed almost similar trends in the increment of available phosphorus contents in post-harvest soils followed by rice hull compost. The other nutrients of post-harvest soils followed the similar trends as that of phosphorus, except for the exchangeable potassium, where rice straw compost at the highest rate (8 t ha-1) exhibit- ed the best response (0.97 c molc kg -1) than those of the other treatments. The maximum amounts of available sulfur, exchangeable calcium and magnesium were obtained from the highest dose of vermicompost and the minimum amounts were attained by the control plot. The trend of increments of all these nutrients were more pronounced with the higher rates of the applied organic amendments indicate that all the applied organic composts are suitable sources for improving nutrient statuses of soils. Pearson correlation and regression analyses also indicate the strong positive relationship between the treatments and nutrient statuses of post-harvest soils (Table VII). The current findings are in consistent with those of Xin et al. (2017). Many steps have been made to improve soil fertility and productivity, according to them. Increased organic input, such as organic manure, compost, and straw integration, are the most effective approaches. Crop straw, a cheap and nutrient-dense material, offers a lot of potential for enhancing soil fertility (Tan et al. 2017). Crop straw, which is high in nutrients and organic elements, can be treated as a natural organic fertilizer and utilized as an alternative to chemical fertilizers, according to the studies of Wang et al. (2017). As a result, straw integration appears to be a potential method for maintaining and restoring soil fertility, the burning issue of present day. Because, mineral elements are required for the healthy growth and development of both plants and humans. The plant roots take up the mineral nutrients from soil and transported them to the edible parts for human consumption through various transporters. For human health, an ideal future crop should be rich in essential mineral elements but with less toxic elements in the edible parts. Still, it is estimat- ed that nearly 2 billion people are suffering from deficiency of nutrients because of low availability of mineral elements in soil and/or low accumulation/bioavailability of mineral elements in edible parts (Graham et al. 2012). This so-called hidden hunger is an especially serious health problem for people subsisting on cereal-based diets because cereals such as rice usually contain a low level of mineral elements as well as low bioavailability (Grebmer et al. 2014; Nakandalage and Seneweera, 2018). On the other hand, rapid urbanization and industrialization cause contamination by toxic elements in many soils used for crop production (Zhao et al. 2010; Clemens and Ma, 2016), which threaten our health throughout the food chain. Therefore, it is extremely important to boost essential nutrients (both density and bioavailability) and reduce toxic elements in edible parts of cereals for human health. Conclusion The present research findings conclude that the locally made organic composts using indigenous organic materi- als had potential to improve soil fertility and provide nutrients for rice production. Significant positive correla- tion between the treatments and mineral nutrients of rice plants confirmed the strong relationship of organic farm- ing for sustainable agriculture. There were significant (p ≤ 0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of amendments under rice production. The nutrition of rice plants grown under field condition was influenced most by the vermi- compost and followed the order of the treatments as rice straw compost > sawdust compost > rice hull compost for the studied variety of rice. These results resemble that the further researches are needed to find out the suitable doses and types of the amendments. However, the applied organ- ic fertilizers were found to have responses on the nutri- tional statuses of rice shoot and post-harvest soils and these might be effective for the nutritional balance of the rice variety and ultimately will be helpful for country’s penniless people to combat their existing and future demand of quality rice. Acknowledgement The study was carried out under a project of the Climate Change Trust Fund (CCTF) titled ‘Assessment of Impacts of Climate Change on Soil Health and Food Security, and Adaptation of Climate-smart Agriculture in Most Adversely Affected Areas of Bangladesh’ through the MoEFCC, Government of the Peoples’ Republic of Bangladesh. The project was implemented in two phases (Phase I: Jan.’17 to Dec.’18, Code 410 DUand Phase II: Jan.’19 to Dec.’22, Code 573 DU) within six years. We are also grateful to the Project staff and relevant officers/staff of the SWED-DU, DU, MoE and MoEFCC of GoB, who performed for the successful completion of the study. References Ahmed S, Alam MJ, Hossain A, Islam AK, Awan TH, Soufan W, Qahtan AA, Okla MK and Sabagh SI (2021), Interactive effect of weeding regimes, rice cultivars, and seeding rates influence the rice-weed competition under dry direct-seeded condition, Sustainability. 13: 317-321. 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DOI: 10.4315/0362-028X.- JFP-18-217 Heitkamp F, Raupp J and Ludwig B (2011), Soil organic matter pools and crop yields as affected by the rate of farmyard manure and use of biodynamic preparations in a sandy soil, Organic Agriculture. 11: 111-124. DOI: 10.1007/s13165-011-0010-7 Jahiruddin M and Satter MA (2010), Research priority in agriculture and development of vision document-2030 and beyond. Land and soil resource management. Bangladesh gricultural Research Council. Dhaka. Jeptoo A, Aguyoh JN and Saidi M (2013), Improving Carrot Yield and Quality through the Use of Bio-Slurry Manure, Sustainable Agricultural Research. 2(1): 164-172. DOI: 10.5539/sar.v2n1p164 Nakandalage N and Seneweera S (2018), Micronutrients useefficiency of crop-plants under changing climate. In Plant Micronutrient Use Efficiency, M.A. Hossain, T. Kamiya, D.J. Burritt, L.-S.P. Tran and T. Fujiwara, eds. (London: Academic Press), pp 209-224. Palaniveloo K, Amran MA, Norhashim NA, Mohamad-Fauzi N, Peng-Hui F, Hui-Wen L, Kai-Lin Y, Jiale L, Chian-Yee MG and Jing-Yi L (2020), Food Waste Composting and Microbial Community Structure Profiling, Processes. 8: 723. DOI: org/10.3390/ pr8060723 Partey ST, Thevathasan NV, Zougmoré RB and Preziosi RF (2018), Improving maize production through nitrogen supply from tenrarely-used organic resources in Ghana, Agrofor Syst. 92: 375-387. DOI: 10.1007/ s10457-016-0035-8 Pituello C, Polese R, Morari F and Berti A (2016), Outcomes from a long-term study on crop residue effects on plant yield and nitrogen use efficiency in contrasting soils, Eur J Agron. 77: 179-187. DOI: 10.1016/j. eja.2015.11.027 Somerville PD, Farrell C, May PB and Livesley SJ (2020), Biochar and compost equally improve urban soil physical and biological properties and tree growth, with no added benefit in combination, Sci Total Environ. 706: 135-736. DOI: 10.1016/j.scitotenv. 2019.135736 Tan D, Liu Z, Jiang L, Luo J and Li J (2017), Long-term potash application and wheat straw return reduced soil potassium fixation and affected crop yields in North China, Nutr Cycl Agroecosyst. DOI: 10.1007/s10705- 017-9843-0 Wang W, Sardans J, Wang C, Pan T, Zeng C, Lai D, Bartrons M and Peñuelas J (2017), Straw Application Strategy to Optimize Nutrient Release in a Southeastern China Rice Cropland, Agronomy. 7. DOI: 10.3390/agronomy 7040084 Xin X, Qin S, Zhang J, Zhu A, Yang W and Zhang X (2017), Yield, phosphorus use efficiency and balance response to substituting long-term chemical fertilizer use with organic manure in a wheat-maize system, Field Crop Res. 208: 27-33. DOI: 10.1016/j.fcr.2017.03.011 Yang HS, Xu MM, Koide RT, Liu Q, Dai YJ, Liu L and Bian XM (2016), Effects of ditch-buried straw return on water percolation, nitrogen leaching and crop yields in a rice-wheat rotation system, J Sc. Food Agric. 96: 1141-1149. DOI: 10.1002/jsfa.7196 Zhang P, Chen X, Wei T, Yang Z, Jia Z, Yang B, Han Q and Ren X (2016), Effects of straw incorporation on the soil nutrient contents, enzyme activities, and crop yield in a semiarid region of China, Soil Tillage Res. 160: 65-72. DOI: 10.1016/j.still.2016.02.006 Zhang Y, Liu Y, Zhang G, Guo X, Sun Z and Li T (2018), The Effects of Rice Straw and Biochar Applications on the Microbial Community in a Soil with a History of Continuous Tomato Planting History, Agronomy. 8. DOI: 10.3390/agronomy8050065 Zhao FJ, McGrath SP and Meharg AA (2010), Arsenic as a food chain contaminant: mechanisms of plant uptake and metabolism and mitigation strategies, Annu Rev Plant Biol. 61: 535-559. DOI: 10.1146/annurev-ar- plant-042809-112152 Table IV. Impacts of applied organic composts on mineral nutrition of rice plant tissues grown during Aman season in Patuakhali district of Bangladesh Treatment Nitrogen Phosphorus Sulfur Potassium Calcium Magnesium Total (g kg-1) T0 = Control 9.6 e 1.1 a 11.9 b 3.86 ab 3.3 a 2.76 T1 = RHC2 11.3 be 1.34 a 13.6 ab 3.32 a 3.92 ab 3.18 T2 = RHC4 13 ab 1.58 ab 13.8 ab 4.5 abc 5.6 abc 3.29 T3 = RHC8 15.7 acd 2.24 ab 14.7 abc 4.96 abc 7.21 cdef 3.35 T4 = RSC2 14.6 ac 2.05 ab 14 ab 3.9 ab 6.13 abcd 3.66 T5 = RSC4 17.1 cdf 2.7 ab 15.5 acd 5.2 abc 8.77 defg 4.71 T6 = RSC8 20.5 gh 3.65 ab 17.9 de 6.79 bc 11.3 gh 4.68 T7 = SDC2 11.6 be 1.78 ab 13.7 ab 4.52 abc 5.05 abc 3.53 T8 = SDC4 14 ab 2.23 ab 14.6 abc 5.09 abc 5.94 abcd 3.82 T9 = SDC8 18.1 dfg 3.12 ab 17.3 cde 6.9 c 9.67 fgh 4.65 T10 = V2 15.7 acd 2.35 ab 16.3 acd 4.55 abc 6.64 bcde 4.09 T11 = V4 18.8 fgh 3.13 ab 17 cde 6.17 abc 9.13 efgh 4.96 T12 = V8 21.4 h 4.42 b 19.7 e 7.27 c 11.87 h 5.54 In a column, means followed by a common letter are not significantly different at 5% level by Tukey’s Range Test Table V. Correlation between the treatments and mineral nutrition of rice plant tissues Nutrition Coefficient Stand. Error t Stat P-value Lower 95% Upper 95% Nitrogen 1.0133 0.2394 4.2322 0.0014 0.4863 1.5403 Phosphorus 0.2588 0.0655 3.9541 0.0023 0.1148 0.4029 Potassium 0.6295 0.1663 3.7864 0.0030 0.2636 0.9955 Sulphur 0.3697 0.0767 4.8205 0.0005 0.2009 0.5385 Calcium 0.7854 0.1656 4.7437 0.0006 0.4210 1.1498 Magnesium 0.1778 0.0706 2.5189 0.0285 0.0224 0.3332 Mineral nutrition of rice and post-harvest soils influenced by self-made organic composts 58(2) 2023104 However, until now, the use of straw incorporation to increase crop yield is still a matter of argument since studies in different climates and soil types have led to inconclusive results (Pituello et al. 2016). It has been reported that straw incorporation has significant valuable effects on crop yields and soil properties. For instance, straw incorporation can increase crop yields (Yang et al. 2016), soil organic matter and other soil nutrients (Zhang et al. 2018). Straw return can also improve soil physical properties, such as by increasing hydraulic conductivity, decreasing bulk density, and enhancing aggregate forma- tion (Yang et al. 2016). Vermicompost is a nourishing organic fertilizer having high amount of humus, nitrogen 2–3%, phosphorous 1.55–2.25%, potassium 1.85–2.25%, micronutrients, more beneficial for soil microbes like ‘nitrogen fixing bacteria’ and mycorrhizal fungi. Vermicompost has been scientifically proved as miracle plant growth enhancer (Guerrero, 2010). Ansari and Ismail (2012) reported that worms vermicompost contains 7.37 % nitrogen and 19.58% phosphorous as P2O5. Microbial population of N2- fixing bacteria and actinomycetes increases by the application of vermicompost. The amplified microbial activities improve the availability of soil phosphorous and nitrogen. Vermicomposting is an aerobic, biological method and is proficient to convert eco-friendly hummus like organic substances (Chanda et al. 2011). Vermicompost stimulates to influence the microbial activity of soil, increases the availability of oxygen, maintains normal soil temperature, increases soil porosity and infiltration of water, improves nutrient content and increases growth, yield and quality of the plant (Arora et al. 2011). Rice hull and sawdust are also important agricultural amendments. Growth and yield components of rice grown in saline soil were found to be increased significantly (p ≤ 0.05) by the application of rice hull, rice straw and sawdust alone and in combination (Akter et al. 2018). The physico-chemical properties and nutrient status of post-harvest soils were also found to be influenced by the application of these amendments (Akter and Khan, 2019). Composting is a low-cost natural way of recycling and stabilizing organic matter under thermophilic temperature that forms a pathogen-free substrate, beneficial to crops (Gurtler et al. 2018; Somerville et al. 2020). Low-income farmers found it more advantageous to them. Composting was found to be a promising practice that brought organic materials to a certain stage by narrowing down its C:N ratio where nutrients are easily accessible to plants (Palaniveloo et al. 2020). Partey et al. (2018) and Dinesh et al. (2011), had consolidated that biomass needs to decompose for making N available to crops. Thus, composting locally available organic amendments (OAs) is essential for a healthy and sustainable agro-ecosystem in different climatic conditions. Therefore, the objectives of the study were to evaluate the nutrient statuses of post-harvest soils and rice plants grown in Aman season as influenced by the different rates of organic composts applied under field condition. Materials and methods Study site and experimental design In Patuakhali a district of Bangladesh, the field experiment was conducted in Bilbilash of Bauphal Upazila (Map I), which is located between 22°20ʹ00ʺN and 90°20ʹ00ʺE longitude within agro-ecological zone-13 named as Ganges Tidal Floodplain. The climatic condition of this area is usually known as ‘tropical monsoon climate’. The area mainly enjoys three seasons such as rainy, dry and summer season. The experiment was carried out following completely randomized block design with the self-made organic composts, such as, Rice Hull Compost (RHC), Rice Straw Compost (RSC), Sawdust Compost (SDC) and Vermicompost (V) corresponding to the rates of 0, 2, 4 and 8 t ha-1 of each organic compost at Aman season during August to December, 2018. There were 13 plots having individual treatment (Table I) in the experimental area, each unit plot size was 16 m2 (4m×4m) and replications were considered within the plot. Selected properties of potential amendments used and initial soils at field site are presented in the Tables II and III. Transplantation following subsequent protocols Basal doses of N, P2O5, and K2O from urea, TSP, and MoP fertilizers were applied at the rates of 40, 30, and 15 kg ha-1, respectively considering soil amendments and initial contents of the nutrients. During field preparation, the TSP, MoP, and half of the urea were applied in their entirety after being thoroughly mixed with the field soil. The remaining urea was top dressed in two splits, one at the beginning of the rice panicle and another at the active tillering stage. Three seedlings per hill of the BR 25 variety, which were thirty days old and in good health, were transplanted. Row to row and hill to hill distances were each 20 and 22 cm, respectively. No irrigation was required for this study for the growth of rice in this season. Intercultur- al operations such as, weeding, pesticide use, etc. were done as per requirement. Sample collection and analyses Plant samples were collected from each plot just after harvesting. Soil samples were collected from 3 spots as replications of each plot of active root zone (0-15 cm) with the help of an auger. Soil samples were then stored treatment wise in polythene bags with proper labeling. After sun drying and grounding the samples were then passed through 2 mm sieve and stored properly in air tight plastic pots for further analyses. The collected plant samples were sun dried and weighed. After sun drying a portion of the collected plant samples were oven dried at 65⁰C and then grinded and stored in air tight plastic pots for laboratory analyses. All the labora- tory analyses were done following standard methods. Statistical analyses Pearson correlation and regression analyses between treatments and mineral nutrition of rice plants, Analysis of Variance (ANOVA) and Tukey’s Range Test at 5% (p≤ 0.05) level were done for the interpretation of the experi- mental results. Results and discussion Mineral nutrition of rice plants The total nitrogen, phosphorus, potassium, sulfur, calcium and magnesium contents at maturity stage of rice plants grown under field condition were significantly (p≤0.05) influenced by the application of variable indigenous organic amendments (rice hull compost, rice straw compost, sawdust compost and vermicompost) during Aman season (Table IV and Fig.1). Pearson correlation and regression analyses have been performed between the different treatments and mineral nutrition of rice plant tissues (Table V). Significance has been determined based on p values whether they were <0.05 or not. The total nitrogen (r = 0.78***), phosphorus (r = 0.77**), potassium (r = 0.75**), sulfur (r = 0.82***), calcium (r = 0.82***) and magnesium (r = 0.60*) contents of the tested rice plant (BR 25) tissues were signifi- cantly correlated with the applied organic composts and these correlations confirmed that the different sources of organic materials positively influenced the nutrition of rice plant tissues which ultimately regulate the edible part (grain) of the rice crops. According to Graham et al. (2012), people taking cereal based diets still suffering from hidden hunger of nutrients due to low level and low bioavailability of essential elements. The present results demonstrated that the nitro- gen content in rice straw increased with the increased rate of the application of organic composts. The maximum nitrogen contents in the rice plant tissues were recorded at V8 treatment for the tested variety. Among the applied composts, vermicompost (18.63 g kg-1N) ranked first followed by rice straw compost (17.40 g kg-1), sawdust compost (14.57g kg-1) and rice hull compost (13.33 g kg-1), regardless of their doses. Phosphorus contents in rice plant tissues increased with the higher rates of the different composts. The highest (4.42 g kg-1) and lowest (1.10 g kg-1) contents of total phosphorus were recorded in the T12 (V8) and T0 (control) treatments. The rest of the above-men- tioned nutrients were exerted the similar trends as those obtained by the P and N contents by the different organic composts. The nutrition of rice shoots was influenced by the direction of vermicompost > rice straw compost > sawdust compost > rice hull compost for the studied variety of rice grown under field condition. Nutrient status of post-harvest soils Rice production during T. Aman season, the available N contents in the post-harvest soils increased significantly (p ≤ 0.05) by the application of vermicompost, rice hull compost, rice straw compost and sawdust compost (Table VI and Fig. 2). The maximum amount of available N (78.29 mg kg-1) was recorded in T3 (RHC8) treatment, where available nitrogen content increased 85.65% as compared to control plot. At the same dose (8 t ha-1), the sawdust compost treatment ranked second for the available nitrogen content (62.31 mg kg-1) at post-harvest soils followed by RSC8 treatment (60.76 mg kg-1). There were significant (p≤0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of the organic amendments under rice production (Table VI). Soils treated with vermicompost at the rate of 8 t ha-1 was found to have significantly more phosphorus (12.57 mg kg-1) as compared to control plot. The rice straw compost and sawdust compost each at 8 t ha-1 were showed almost similar trends in the increment of available phosphorus contents in post-harvest soils followed by rice hull compost. The other nutrients of post-harvest soils followed the similar trends as that of phosphorus, except for the exchangeable potassium, where rice straw compost at the highest rate (8 t ha-1) exhibit- ed the best response (0.97 c molc kg -1) than those of the other treatments. The maximum amounts of available sulfur, exchangeable calcium and magnesium were obtained from the highest dose of vermicompost and the minimum amounts were attained by the control plot. The trend of increments of all these nutrients were more pronounced with the higher rates of the applied organic amendments indicate that all the applied organic composts are suitable sources for improving nutrient statuses of soils. Pearson correlation and regression analyses also indicate the strong positive relationship between the treatments and nutrient statuses of post-harvest soils (Table VII). The current findings are in consistent with those of Xin et al. (2017). Many steps have been made to improve soil fertility and productivity, according to them. Increased organic input, such as organic manure, compost, and straw integration, are the most effective approaches. Crop straw, a cheap and nutrient-dense material, offers a lot of potential for enhancing soil fertility (Tan et al. 2017). Crop straw, which is high in nutrients and organic elements, can be treated as a natural organic fertilizer and utilized as an alternative to chemical fertilizers, according to the studies of Wang et al. (2017). As a result, straw integration appears to be a potential method for maintaining and restoring soil fertility, the burning issue of present day. Because, mineral elements are required for the healthy growth and development of both plants and humans. The plant roots take up the mineral nutrients from soil and transported them to the edible parts for human consumption through various transporters. For human health, an ideal future crop should be rich in essential mineral elements but with less toxic elements in the edible parts. Still, it is estimat- ed that nearly 2 billion people are suffering from deficiency of nutrients because of low availability of mineral elements in soil and/or low accumulation/bioavailability of mineral elements in edible parts (Graham et al. 2012). This so-called hidden hunger is an especially serious health problem for people subsisting on cereal-based diets because cereals such as rice usually contain a low level of mineral elements as well as low bioavailability (Grebmer et al. 2014; Nakandalage and Seneweera, 2018). On the other hand, rapid urbanization and industrialization cause contamination by toxic elements in many soils used for crop production (Zhao et al. 2010; Clemens and Ma, 2016), which threaten our health throughout the food chain. Therefore, it is extremely important to boost essential nutrients (both density and bioavailability) and reduce toxic elements in edible parts of cereals for human health. Conclusion The present research findings conclude that the locally made organic composts using indigenous organic materi- als had potential to improve soil fertility and provide nutrients for rice production. Significant positive correla- tion between the treatments and mineral nutrients of rice plants confirmed the strong relationship of organic farm- ing for sustainable agriculture. There were significant (p ≤ 0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of amendments under rice production. The nutrition of rice plants grown under field condition was influenced most by the vermi- compost and followed the order of the treatments as rice straw compost > sawdust compost > rice hull compost for the studied variety of rice. These results resemble that the further researches are needed to find out the suitable doses and types of the amendments. However, the applied organ- ic fertilizers were found to have responses on the nutri- tional statuses of rice shoot and post-harvest soils and these might be effective for the nutritional balance of the rice variety and ultimately will be helpful for country’s penniless people to combat their existing and future demand of quality rice. Acknowledgement The study was carried out under a project of the Climate Change Trust Fund (CCTF) titled ‘Assessment of Impacts of Climate Change on Soil Health and Food Security, and Adaptation of Climate-smart Agriculture in Most Adversely Affected Areas of Bangladesh’ through the MoEFCC, Government of the Peoples’ Republic of Bangladesh. The project was implemented in two phases (Phase I: Jan.’17 to Dec.’18, Code 410 DUand Phase II: Jan.’19 to Dec.’22, Code 573 DU) within six years. We are also grateful to the Project staff and relevant officers/staff of the SWED-DU, DU, MoE and MoEFCC of GoB, who performed for the successful completion of the study. References Ahmed S, Alam MJ, Hossain A, Islam AK, Awan TH, Soufan W, Qahtan AA, Okla MK and Sabagh SI (2021), Interactive effect of weeding regimes, rice cultivars, and seeding rates influence the rice-weed competition under dry direct-seeded condition, Sustainability. 13: 317-321. DOI: 10.3390/su13010317 Akter S and Khan HR (2019), Influence of rice hull, rice straw, sawdust and moisture levels on selected proper- ties of post harvested saline soils under variable condi- tions of rice cultivation, National University Journal of Science. 6(1): 61-74. Akter S, Khan HR, Hossain MS, Saha MK and Farzana F (2018), Response of rice grown in saline soil as influenced by the application of agricultural amend- ments and moisture regimes, J biodivers conserv bioresour manag. 4(2): 33-42. DOI: https://doi.org/ 10.3329/jbcbm.v4i2.39845 Ansari AA and Ismail SA (2012), Role of Earthworms in Vermtechnology, J Agric Technol. 8(2): 405-415. https://www.ijat-aatsea.com Arora VK, Singh CB, Sidhu AS and Thind SS (2011), Irriga- tion, tillage and mulching effects on Soybean yield and water productivity in relation to soil texture, Agric Water Manag. 98(4): 563-568. https://- doi.org/10.1016/j.agwat .2010.10.004 BBS (2017), Bangladesh Bureau of Statistics. The Year Book of Agricultural Statistics of Bangladesh. Stat. Div. Minis. Planning, Govt. Peoples Repub. Bangladesh, Dhaka. BBS (2020), Summary Crop Statistics and Crop Indices (2019-2020). Bangladesh Bureau of Statistics Division, Govt. of the People’s Republic of Bangla- desh: Dhaka, Bangladesh. pp 35-37. Chanda GC, Bhunia G and Chakraborty SK (2011), The effect of vermicompost and other fertilizers on cultiva- tion of Tomato plants, J Hortic For. 3: 42-45. http://w- ww.acade mic journals.org/jhf Clemens S and Ma JF (2016), Toxic heavy metal and metal- loid accumulation in crop plants and foods, Annu Rev Plant Biol. 67: 489-512. DOI: 10.1146/annurev-ar- plant-043015-112301 Dinesh R, Suryanarayana MA, Nair AK and Chaudhuri SG (2011), Leguminous cover crop effects on nitrogen mineralization rates and kinetics in soils, J Agron Crop Sci. 187: 161-166. DOI: 10.1046/j.1439-037x. 2001. 00512.x FRG (2012), (Fertilizer Recommendation Guide). Bangladesh Agricultural Research Council (BARC), Dhaka, Bangladesh. Graham RD, Knez M and Welch RM (2012), How much nutritional iron deficiency in humans globally is due to an underlying zinc deficiency, Adv Agron. 1-40. DOI: 10.1016/B978-0-12-394276-0.00001-9 Grebmer BKV, Saltzman A, Birol E, Wiesmann D, Prasai N, YinS, Yohannes Y, Menon P, Thompson J and Sonntag A (2014), 2014 Global Hunger Index: The Challenge of Hidden Hunger (Washington, DC: International Food Policy Research Institute), pp 56. DOI: http://dx- .doi.org/10.2499/9780896299580 Guerrero RD (2010), Vermicompost production and its use for crop production in the Philippines, International Journal of Global Environmental Issues. 10(3/4): 378-383. DOI: 10.1504/IJGENVI.2010.037278 Gurtler JB, Doyle MP, Erickson MC, Jiang X, Millner P and Sharma M (2018), Composting to inactivate food borne pathogens for crop soil application, A review J Food Prot.81: 1821-1837. DOI: 10.4315/0362-028X.- JFP-18-217 Heitkamp F, Raupp J and Ludwig B (2011), Soil organic matter pools and crop yields as affected by the rate of farmyard manure and use of biodynamic preparations in a sandy soil, Organic Agriculture. 11: 111-124. DOI: 10.1007/s13165-011-0010-7 Jahiruddin M and Satter MA (2010), Research priority in agriculture and development of vision document-2030 and beyond. Land and soil resource management. Bangladesh gricultural Research Council. Dhaka. Jeptoo A, Aguyoh JN and Saidi M (2013), Improving Carrot Yield and Quality through the Use of Bio-Slurry Manure, Sustainable Agricultural Research. 2(1): 164-172. DOI: 10.5539/sar.v2n1p164 Nakandalage N and Seneweera S (2018), Micronutrients useefficiency of crop-plants under changing climate. In Plant Micronutrient Use Efficiency, M.A. Hossain, T. Kamiya, D.J. Burritt, L.-S.P. Tran and T. Fujiwara, eds. (London: Academic Press), pp 209-224. Palaniveloo K, Amran MA, Norhashim NA, Mohamad-Fauzi N, Peng-Hui F, Hui-Wen L, Kai-Lin Y, Jiale L, Chian-Yee MG and Jing-Yi L (2020), Food Waste Composting and Microbial Community Structure Profiling, Processes. 8: 723. DOI: org/10.3390/ pr8060723 Partey ST, Thevathasan NV, Zougmoré RB and Preziosi RF (2018), Improving maize production through nitrogen supply from tenrarely-used organic resources in Ghana, Agrofor Syst. 92: 375-387. DOI: 10.1007/ s10457-016-0035-8 Pituello C, Polese R, Morari F and Berti A (2016), Outcomes from a long-term study on crop residue effects on plant yield and nitrogen use efficiency in contrasting soils, Eur J Agron. 77: 179-187. DOI: 10.1016/j. eja.2015.11.027 Somerville PD, Farrell C, May PB and Livesley SJ (2020), Biochar and compost equally improve urban soil physical and biological properties and tree growth, with no added benefit in combination, Sci Total Environ. 706: 135-736. DOI: 10.1016/j.scitotenv. 2019.135736 Tan D, Liu Z, Jiang L, Luo J and Li J (2017), Long-term potash application and wheat straw return reduced soil potassium fixation and affected crop yields in North China, Nutr Cycl Agroecosyst. DOI: 10.1007/s10705- 017-9843-0 Wang W, Sardans J, Wang C, Pan T, Zeng C, Lai D, Bartrons M and Peñuelas J (2017), Straw Application Strategy to Optimize Nutrient Release in a Southeastern China Rice Cropland, Agronomy. 7. DOI: 10.3390/agronomy 7040084 Xin X, Qin S, Zhang J, Zhu A, Yang W and Zhang X (2017), Yield, phosphorus use efficiency and balance response to substituting long-term chemical fertilizer use with organic manure in a wheat-maize system, Field Crop Res. 208: 27-33. DOI: 10.1016/j.fcr.2017.03.011 Yang HS, Xu MM, Koide RT, Liu Q, Dai YJ, Liu L and Bian XM (2016), Effects of ditch-buried straw return on water percolation, nitrogen leaching and crop yields in a rice-wheat rotation system, J Sc. Food Agric. 96: 1141-1149. DOI: 10.1002/jsfa.7196 Zhang P, Chen X, Wei T, Yang Z, Jia Z, Yang B, Han Q and Ren X (2016), Effects of straw incorporation on the soil nutrient contents, enzyme activities, and crop yield in a semiarid region of China, Soil Tillage Res. 160: 65-72. DOI: 10.1016/j.still.2016.02.006 Zhang Y, Liu Y, Zhang G, Guo X, Sun Z and Li T (2018), The Effects of Rice Straw and Biochar Applications on the Microbial Community in a Soil with a History of Continuous Tomato Planting History, Agronomy. 8. DOI: 10.3390/agronomy8050065 Zhao FJ, McGrath SP and Meharg AA (2010), Arsenic as a food chain contaminant: mechanisms of plant uptake and metabolism and mitigation strategies, Annu Rev Plant Biol. 61: 535-559. DOI: 10.1146/annurev-ar- plant-042809-112152 Fig. 1. Relationship between applied organic composts and mineral nutrition of rice plant tissues *,**,*** indicate the significant levels of correlation at 5%, 1% and 0.1%, respectively. Akter, Khan and Saha 95 However, until now, the use of straw incorporation to increase crop yield is still a matter of argument since studies in different climates and soil types have led to inconclusive results (Pituello et al. 2016). It has been reported that straw incorporation has significant valuable effects on crop yields and soil properties. For instance, straw incorporation can increase crop yields (Yang et al. 2016), soil organic matter and other soil nutrients (Zhang et al. 2018). Straw return can also improve soil physical properties, such as by increasing hydraulic conductivity, decreasing bulk density, and enhancing aggregate forma- tion (Yang et al. 2016). Vermicompost is a nourishing organic fertilizer having high amount of humus, nitrogen 2–3%, phosphorous 1.55–2.25%, potassium 1.85–2.25%, micronutrients, more beneficial for soil microbes like ‘nitrogen fixing bacteria’ and mycorrhizal fungi. Vermicompost has been scientifically proved as miracle plant growth enhancer (Guerrero, 2010). Ansari and Ismail (2012) reported that worms vermicompost contains 7.37 % nitrogen and 19.58% phosphorous as P2O5. Microbial population of N2- fixing bacteria and actinomycetes increases by the application of vermicompost. The amplified microbial activities improve the availability of soil phosphorous and nitrogen. Vermicomposting is an aerobic, biological method and is proficient to convert eco-friendly hummus like organic substances (Chanda et al. 2011). Vermicompost stimulates to influence the microbial activity of soil, increases the availability of oxygen, maintains normal soil temperature, increases soil porosity and infiltration of water, improves nutrient content and increases growth, yield and quality of the plant (Arora et al. 2011). Rice hull and sawdust are also important agricultural amendments. Growth and yield components of rice grown in saline soil were found to be increased significantly (p ≤ 0.05) by the application of rice hull, rice straw and sawdust alone and in combination (Akter et al. 2018). The physico-chemical properties and nutrient status of post-harvest soils were also found to be influenced by the application of these amendments (Akter and Khan, 2019). Composting is a low-cost natural way of recycling and stabilizing organic matter under thermophilic temperature that forms a pathogen-free substrate, beneficial to crops (Gurtler et al. 2018; Somerville et al. 2020). Low-income farmers found it more advantageous to them. Composting was found to be a promising practice that brought organic materials to a certain stage by narrowing down its C:N ratio where nutrients are easily accessible to plants (Palaniveloo et al. 2020). Partey et al. (2018) and Dinesh et al. (2011), had consolidated that biomass needs to decompose for making N available to crops. Thus, composting locally available organic amendments (OAs) is essential for a healthy and sustainable agro-ecosystem in different climatic conditions. Therefore, the objectives of the study were to evaluate the nutrient statuses of post-harvest soils and rice plants grown in Aman season as influenced by the different rates of organic composts applied under field condition. Materials and methods Study site and experimental design In Patuakhali a district of Bangladesh, the field experiment was conducted in Bilbilash of Bauphal Upazila (Map I), which is located between 22°20ʹ00ʺN and 90°20ʹ00ʺE longitude within agro-ecological zone-13 named as Ganges Tidal Floodplain. The climatic condition of this area is usually known as ‘tropical monsoon climate’. The area mainly enjoys three seasons such as rainy, dry and summer season. The experiment was carried out following completely randomized block design with the self-made organic composts, such as, Rice Hull Compost (RHC), Rice Straw Compost (RSC), Sawdust Compost (SDC) and Vermicompost (V) corresponding to the rates of 0, 2, 4 and 8 t ha-1 of each organic compost at Aman season during August to December, 2018. There were 13 plots having individual treatment (Table I) in the experimental area, each unit plot size was 16 m2 (4m×4m) and replications were considered within the plot. Selected properties of potential amendments used and initial soils at field site are presented in the Tables II and III. Transplantation following subsequent protocols Basal doses of N, P2O5, and K2O from urea, TSP, and MoP fertilizers were applied at the rates of 40, 30, and 15 kg ha-1, respectively considering soil amendments and initial contents of the nutrients. During field preparation, the TSP, MoP, and half of the urea were applied in their entirety after being thoroughly mixed with the field soil. The remaining urea was top dressed in two splits, one at the beginning of the rice panicle and another at the active tillering stage. Three seedlings per hill of the BR 25 variety, which were thirty days old and in good health, were transplanted. Row to row and hill to hill distances were each 20 and 22 cm, respectively. No irrigation was required for this study for the growth of rice in this season. Intercultur- al operations such as, weeding, pesticide use, etc. were done as per requirement. Sample collection and analyses Plant samples were collected from each plot just after harvesting. Soil samples were collected from 3 spots as replications of each plot of active root zone (0-15 cm) with the help of an auger. Soil samples were then stored treatment wise in polythene bags with proper labeling. After sun drying and grounding the samples were then passed through 2 mm sieve and stored properly in air tight plastic pots for further analyses. The collected plant samples were sun dried and weighed. After sun drying a portion of the collected plant samples were oven dried at 65⁰C and then grinded and stored in air tight plastic pots for laboratory analyses. All the labora- tory analyses were done following standard methods. Statistical analyses Pearson correlation and regression analyses between treatments and mineral nutrition of rice plants, Analysis of Variance (ANOVA) and Tukey’s Range Test at 5% (p≤ 0.05) level were done for the interpretation of the experi- mental results. Results and discussion Mineral nutrition of rice plants The total nitrogen, phosphorus, potassium, sulfur, calcium and magnesium contents at maturity stage of rice plants grown under field condition were significantly (p≤0.05) influenced by the application of variable indigenous organic amendments (rice hull compost, rice straw compost, sawdust compost and vermicompost) during Aman season (Table IV and Fig.1). Pearson correlation and regression analyses have been performed between the different treatments and mineral nutrition of rice plant tissues (Table V). Significance has been determined based on p values whether they were <0.05 or not. The total nitrogen (r = 0.78***), phosphorus (r = 0.77**), potassium (r = 0.75**), sulfur (r = 0.82***), calcium (r = 0.82***) and magnesium (r = 0.60*) contents of the tested rice plant (BR 25) tissues were signifi- cantly correlated with the applied organic composts and these correlations confirmed that the different sources of organic materials positively influenced the nutrition of rice plant tissues which ultimately regulate the edible part (grain) of the rice crops. According to Graham et al. (2012), people taking cereal based diets still suffering from hidden hunger of nutrients due to low level and low bioavailability of essential elements. The present results demonstrated that the nitro- gen content in rice straw increased with the increased rate of the application of organic composts. The maximum nitrogen contents in the rice plant tissues were recorded at V8 treatment for the tested variety. Among the applied composts, vermicompost (18.63 g kg-1N) ranked first followed by rice straw compost (17.40 g kg-1), sawdust compost (14.57g kg-1) and rice hull compost (13.33 g kg-1), regardless of their doses. Phosphorus contents in rice plant tissues increased with the higher rates of the different composts. The highest (4.42 g kg-1) and lowest (1.10 g kg-1) contents of total phosphorus were recorded in the T12 (V8) and T0 (control) treatments. The rest of the above-men- tioned nutrients were exerted the similar trends as those obtained by the P and N contents by the different organic composts. The nutrition of rice shoots was influenced by the direction of vermicompost > rice straw compost > sawdust compost > rice hull compost for the studied variety of rice grown under field condition. Nutrient status of post-harvest soils Rice production during T. Aman season, the available N contents in the post-harvest soils increased significantly (p ≤ 0.05) by the application of vermicompost, rice hull compost, rice straw compost and sawdust compost (Table VI and Fig. 2). The maximum amount of available N (78.29 mg kg-1) was recorded in T3 (RHC8) treatment, where available nitrogen content increased 85.65% as compared to control plot. At the same dose (8 t ha-1), the sawdust compost treatment ranked second for the available nitrogen content (62.31 mg kg-1) at post-harvest soils followed by RSC8 treatment (60.76 mg kg-1). There were significant (p≤0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of the organic amendments under rice production (Table VI). Soils treated with vermicompost at the rate of 8 t ha-1 was found to have significantly more phosphorus (12.57 mg kg-1) as compared to control plot. The rice straw compost and sawdust compost each at 8 t ha-1 were showed almost similar trends in the increment of available phosphorus contents in post-harvest soils followed by rice hull compost. The other nutrients of post-harvest soils followed the similar trends as that of phosphorus, except for the exchangeable potassium, where rice straw compost at the highest rate (8 t ha-1) exhibit- ed the best response (0.97 c molc kg -1) than those of the other treatments. The maximum amounts of available sulfur, exchangeable calcium and magnesium were obtained from the highest dose of vermicompost and the minimum amounts were attained by the control plot. The trend of increments of all these nutrients were more pronounced with the higher rates of the applied organic amendments indicate that all the applied organic composts are suitable sources for improving nutrient statuses of soils. Pearson correlation and regression analyses also indicate the strong positive relationship between the treatments and nutrient statuses of post-harvest soils (Table VII). The current findings are in consistent with those of Xin et al. (2017). Many steps have been made to improve soil fertility and productivity, according to them. Increased organic input, such as organic manure, compost, and straw integration, are the most effective approaches. Crop straw, a cheap and nutrient-dense material, offers a lot of potential for enhancing soil fertility (Tan et al. 2017). Crop straw, which is high in nutrients and organic elements, can be treated as a natural organic fertilizer and utilized as an alternative to chemical fertilizers, according to the studies of Wang et al. (2017). As a result, straw integration appears to be a potential method for maintaining and restoring soil fertility, the burning issue of present day. Because, mineral elements are required for the healthy growth and development of both plants and humans. The plant roots take up the mineral nutrients from soil and transported them to the edible parts for human consumption through various transporters. For human health, an ideal future crop should be rich in essential mineral elements but with less toxic elements in the edible parts. Still, it is estimat- ed that nearly 2 billion people are suffering from deficiency of nutrients because of low availability of mineral elements in soil and/or low accumulation/bioavailability of mineral elements in edible parts (Graham et al. 2012). This so-called hidden hunger is an especially serious health problem for people subsisting on cereal-based diets because cereals such as rice usually contain a low level of mineral elements as well as low bioavailability (Grebmer et al. 2014; Nakandalage and Seneweera, 2018). On the other hand, rapid urbanization and industrialization cause contamination by toxic elements in many soils used for crop production (Zhao et al. 2010; Clemens and Ma, 2016), which threaten our health throughout the food chain. Therefore, it is extremely important to boost essential nutrients (both density and bioavailability) and reduce toxic elements in edible parts of cereals for human health. Conclusion The present research findings conclude that the locally made organic composts using indigenous organic materi- als had potential to improve soil fertility and provide nutrients for rice production. Significant positive correla- tion between the treatments and mineral nutrients of rice plants confirmed the strong relationship of organic farm- ing for sustainable agriculture. There were significant (p ≤ 0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of amendments under rice production. The nutrition of rice plants grown under field condition was influenced most by the vermi- compost and followed the order of the treatments as rice straw compost > sawdust compost > rice hull compost for the studied variety of rice. These results resemble that the further researches are needed to find out the suitable doses and types of the amendments. However, the applied organ- ic fertilizers were found to have responses on the nutri- tional statuses of rice shoot and post-harvest soils and these might be effective for the nutritional balance of the rice variety and ultimately will be helpful for country’s penniless people to combat their existing and future demand of quality rice. Acknowledgement The study was carried out under a project of the Climate Change Trust Fund (CCTF) titled ‘Assessment of Impacts of Climate Change on Soil Health and Food Security, and Adaptation of Climate-smart Agriculture in Most Adversely Affected Areas of Bangladesh’ through the MoEFCC, Government of the Peoples’ Republic of Bangladesh. The project was implemented in two phases (Phase I: Jan.’17 to Dec.’18, Code 410 DUand Phase II: Jan.’19 to Dec.’22, Code 573 DU) within six years. We are also grateful to the Project staff and relevant officers/staff of the SWED-DU, DU, MoE and MoEFCC of GoB, who performed for the successful completion of the study. References Ahmed S, Alam MJ, Hossain A, Islam AK, Awan TH, Soufan W, Qahtan AA, Okla MK and Sabagh SI (2021), Interactive effect of weeding regimes, rice cultivars, and seeding rates influence the rice-weed competition under dry direct-seeded condition, Sustainability. 13: 317-321. DOI: 10.3390/su13010317 Akter S and Khan HR (2019), Influence of rice hull, rice straw, sawdust and moisture levels on selected proper- ties of post harvested saline soils under variable condi- tions of rice cultivation, National University Journal of Science. 6(1): 61-74. Akter S, Khan HR, Hossain MS, Saha MK and Farzana F (2018), Response of rice grown in saline soil as influenced by the application of agricultural amend- ments and moisture regimes, J biodivers conserv bioresour manag. 4(2): 33-42. DOI: https://doi.org/ 10.3329/jbcbm.v4i2.39845 Ansari AA and Ismail SA (2012), Role of Earthworms in Vermtechnology, J Agric Technol. 8(2): 405-415. https://www.ijat-aatsea.com Arora VK, Singh CB, Sidhu AS and Thind SS (2011), Irriga- tion, tillage and mulching effects on Soybean yield and water productivity in relation to soil texture, Agric Water Manag. 98(4): 563-568. https://- doi.org/10.1016/j.agwat .2010.10.004 BBS (2017), Bangladesh Bureau of Statistics. The Year Book of Agricultural Statistics of Bangladesh. Stat. Div. Minis. Planning, Govt. Peoples Repub. Bangladesh, Dhaka. BBS (2020), Summary Crop Statistics and Crop Indices (2019-2020). Bangladesh Bureau of Statistics Division, Govt. of the People’s Republic of Bangla- desh: Dhaka, Bangladesh. pp 35-37. Chanda GC, Bhunia G and Chakraborty SK (2011), The effect of vermicompost and other fertilizers on cultiva- tion of Tomato plants, J Hortic For. 3: 42-45. http://w- ww.acade mic journals.org/jhf Clemens S and Ma JF (2016), Toxic heavy metal and metal- loid accumulation in crop plants and foods, Annu Rev Plant Biol. 67: 489-512. DOI: 10.1146/annurev-ar- plant-043015-112301 Dinesh R, Suryanarayana MA, Nair AK and Chaudhuri SG (2011), Leguminous cover crop effects on nitrogen mineralization rates and kinetics in soils, J Agron Crop Sci. 187: 161-166. DOI: 10.1046/j.1439-037x. 2001. 00512.x FRG (2012), (Fertilizer Recommendation Guide). Bangladesh Agricultural Research Council (BARC), Dhaka, Bangladesh. Graham RD, Knez M and Welch RM (2012), How much nutritional iron deficiency in humans globally is due to an underlying zinc deficiency, Adv Agron. 1-40. DOI: 10.1016/B978-0-12-394276-0.00001-9 Grebmer BKV, Saltzman A, Birol E, Wiesmann D, Prasai N, YinS, Yohannes Y, Menon P, Thompson J and Sonntag A (2014), 2014 Global Hunger Index: The Challenge of Hidden Hunger (Washington, DC: International Food Policy Research Institute), pp 56. DOI: http://dx- .doi.org/10.2499/9780896299580 Guerrero RD (2010), Vermicompost production and its use for crop production in the Philippines, International Journal of Global Environmental Issues. 10(3/4): 378-383. DOI: 10.1504/IJGENVI.2010.037278 Gurtler JB, Doyle MP, Erickson MC, Jiang X, Millner P and Sharma M (2018), Composting to inactivate food borne pathogens for crop soil application, A review J Food Prot.81: 1821-1837. DOI: 10.4315/0362-028X.- JFP-18-217 Heitkamp F, Raupp J and Ludwig B (2011), Soil organic matter pools and crop yields as affected by the rate of farmyard manure and use of biodynamic preparations in a sandy soil, Organic Agriculture. 11: 111-124. DOI: 10.1007/s13165-011-0010-7 Jahiruddin M and Satter MA (2010), Research priority in agriculture and development of vision document-2030 and beyond. Land and soil resource management. Bangladesh gricultural Research Council. Dhaka. Jeptoo A, Aguyoh JN and Saidi M (2013), Improving Carrot Yield and Quality through the Use of Bio-Slurry Manure, Sustainable Agricultural Research. 2(1): 164-172. DOI: 10.5539/sar.v2n1p164 Nakandalage N and Seneweera S (2018), Micronutrients useefficiency of crop-plants under changing climate. In Plant Micronutrient Use Efficiency, M.A. Hossain, T. Kamiya, D.J. Burritt, L.-S.P. Tran and T. Fujiwara, eds. (London: Academic Press), pp 209-224. Palaniveloo K, Amran MA, Norhashim NA, Mohamad-Fauzi N, Peng-Hui F, Hui-Wen L, Kai-Lin Y, Jiale L, Chian-Yee MG and Jing-Yi L (2020), Food Waste Composting and Microbial Community Structure Profiling, Processes. 8: 723. DOI: org/10.3390/ pr8060723 Partey ST, Thevathasan NV, Zougmoré RB and Preziosi RF (2018), Improving maize production through nitrogen supply from tenrarely-used organic resources in Ghana, Agrofor Syst. 92: 375-387. DOI: 10.1007/ s10457-016-0035-8 Pituello C, Polese R, Morari F and Berti A (2016), Outcomes from a long-term study on crop residue effects on plant yield and nitrogen use efficiency in contrasting soils, Eur J Agron. 77: 179-187. DOI: 10.1016/j. eja.2015.11.027 Somerville PD, Farrell C, May PB and Livesley SJ (2020), Biochar and compost equally improve urban soil physical and biological properties and tree growth, with no added benefit in combination, Sci Total Environ. 706: 135-736. DOI: 10.1016/j.scitotenv. 2019.135736 Tan D, Liu Z, Jiang L, Luo J and Li J (2017), Long-term potash application and wheat straw return reduced soil potassium fixation and affected crop yields in North China, Nutr Cycl Agroecosyst. DOI: 10.1007/s10705- 017-9843-0 Wang W, Sardans J, Wang C, Pan T, Zeng C, Lai D, Bartrons M and Peñuelas J (2017), Straw Application Strategy to Optimize Nutrient Release in a Southeastern China Rice Cropland, Agronomy. 7. DOI: 10.3390/agronomy 7040084 Xin X, Qin S, Zhang J, Zhu A, Yang W and Zhang X (2017), Yield, phosphorus use efficiency and balance response to substituting long-term chemical fertilizer use with organic manure in a wheat-maize system, Field Crop Res. 208: 27-33. DOI: 10.1016/j.fcr.2017.03.011 Yang HS, Xu MM, Koide RT, Liu Q, Dai YJ, Liu L and Bian XM (2016), Effects of ditch-buried straw return on water percolation, nitrogen leaching and crop yields in a rice-wheat rotation system, J Sc. Food Agric. 96: 1141-1149. DOI: 10.1002/jsfa.7196 Zhang P, Chen X, Wei T, Yang Z, Jia Z, Yang B, Han Q and Ren X (2016), Effects of straw incorporation on the soil nutrient contents, enzyme activities, and crop yield in a semiarid region of China, Soil Tillage Res. 160: 65-72. DOI: 10.1016/j.still.2016.02.006 Zhang Y, Liu Y, Zhang G, Guo X, Sun Z and Li T (2018), The Effects of Rice Straw and Biochar Applications on the Microbial Community in a Soil with a History of Continuous Tomato Planting History, Agronomy. 8. DOI: 10.3390/agronomy8050065 Zhao FJ, McGrath SP and Meharg AA (2010), Arsenic as a food chain contaminant: mechanisms of plant uptake and metabolism and mitigation strategies, Annu Rev Plant Biol. 61: 535-559. DOI: 10.1146/annurev-ar- plant-042809-112152 Table VI. Impacts of applied organic composts on nutrient statuses of post-harvest soils under rice production during Aman season in Patuakhali district of Bangladesh Treatment Nitrogen Phosphorus Sulfur Potassium Calcium Magnesium Available (mg kg-1) Exchangeable (c molckg -1) T0 = Control 42.17 d 7.17 e 19.83 c 0.23 g 5.52 c 2.93 d T1 = RHC2 56.75 bc 8.37 e 21.38 bc 0.44 e 6.26 b 3.12 cd T2 = RHC4 61.14 b 9.89 cd 22.51 bc 0.87 ab 7.14 b 3.37 c T3 = RHC8 78.29 a 10.56 c 23.64 b 0.93 ab 8.17 ab 3.85 b T4 = RSC2 51.54 cd 9.85 cd 22.14 bc 0.52 d 6.57 b 3.20 cd T5 = RSC4 58.24 bc 10.16 23.21 b 0.71 c 7.29 b 3.46 bc T6 = RSC8 60.76 b 11.84 ab 24.19 b 0.97 a 8.36 ab 4.19 ab T7 = SDC2 49.68 cd 8.83 de 22.34 bc 0.35 f 5.79 c 2.96 cd T8 = SDC4 56.87 bc 10.19 23.15 b 0.62 cd 6.78 b 3.54 bc T9 = SDC8 62.31 b 11.86 ab 24.78 ab 0.94 ab 8.13 ab 3.81 b T10 = V2 47.32 d 9.63 cd 25.21 ab 0.61 cd 7.13 b 3.16 cd T11 = V4 53.76 c 10.85 bc 26.93 ab 0.85 b 8.27 ab 3.54 bc T12 = V8 57.74 bc 12.57 a 27.62 a 0.94 ab 8.92 a 4.48 a Fig. 2. Relationship between applied organic composts and nutrient statuses of post-harvest soils Mineral nutrition of rice and post-harvest soils influenced by self-made organic composts96 58(2) 2023 However, until now, the use of straw incorporation to increase crop yield is still a matter of argument since studies in different climates and soil types have led to inconclusive results (Pituello et al. 2016). It has been reported that straw incorporation has significant valuable effects on crop yields and soil properties. For instance, straw incorporation can increase crop yields (Yang et al. 2016), soil organic matter and other soil nutrients (Zhang et al. 2018). Straw return can also improve soil physical properties, such as by increasing hydraulic conductivity, decreasing bulk density, and enhancing aggregate forma- tion (Yang et al. 2016). Vermicompost is a nourishing organic fertilizer having high amount of humus, nitrogen 2–3%, phosphorous 1.55–2.25%, potassium 1.85–2.25%, micronutrients, more beneficial for soil microbes like ‘nitrogen fixing bacteria’ and mycorrhizal fungi. Vermicompost has been scientifically proved as miracle plant growth enhancer (Guerrero, 2010). Ansari and Ismail (2012) reported that worms vermicompost contains 7.37 % nitrogen and 19.58% phosphorous as P2O5. Microbial population of N2- fixing bacteria and actinomycetes increases by the application of vermicompost. The amplified microbial activities improve the availability of soil phosphorous and nitrogen. Vermicomposting is an aerobic, biological method and is proficient to convert eco-friendly hummus like organic substances (Chanda et al. 2011). Vermicompost stimulates to influence the microbial activity of soil, increases the availability of oxygen, maintains normal soil temperature, increases soil porosity and infiltration of water, improves nutrient content and increases growth, yield and quality of the plant (Arora et al. 2011). Rice hull and sawdust are also important agricultural amendments. Growth and yield components of rice grown in saline soil were found to be increased significantly (p ≤ 0.05) by the application of rice hull, rice straw and sawdust alone and in combination (Akter et al. 2018). The physico-chemical properties and nutrient status of post-harvest soils were also found to be influenced by the application of these amendments (Akter and Khan, 2019). Composting is a low-cost natural way of recycling and stabilizing organic matter under thermophilic temperature that forms a pathogen-free substrate, beneficial to crops (Gurtler et al. 2018; Somerville et al. 2020). Low-income farmers found it more advantageous to them. Composting was found to be a promising practice that brought organic materials to a certain stage by narrowing down its C:N ratio where nutrients are easily accessible to plants (Palaniveloo et al. 2020). Partey et al. (2018) and Dinesh et al. (2011), had consolidated that biomass needs to decompose for making N available to crops. Thus, composting locally available organic amendments (OAs) is essential for a healthy and sustainable agro-ecosystem in different climatic conditions. Therefore, the objectives of the study were to evaluate the nutrient statuses of post-harvest soils and rice plants grown in Aman season as influenced by the different rates of organic composts applied under field condition. Materials and methods Study site and experimental design In Patuakhali a district of Bangladesh, the field experiment was conducted in Bilbilash of Bauphal Upazila (Map I), which is located between 22°20ʹ00ʺN and 90°20ʹ00ʺE longitude within agro-ecological zone-13 named as Ganges Tidal Floodplain. The climatic condition of this area is usually known as ‘tropical monsoon climate’. The area mainly enjoys three seasons such as rainy, dry and summer season. The experiment was carried out following completely randomized block design with the self-made organic composts, such as, Rice Hull Compost (RHC), Rice Straw Compost (RSC), Sawdust Compost (SDC) and Vermicompost (V) corresponding to the rates of 0, 2, 4 and 8 t ha-1 of each organic compost at Aman season during August to December, 2018. There were 13 plots having individual treatment (Table I) in the experimental area, each unit plot size was 16 m2 (4m×4m) and replications were considered within the plot. Selected properties of potential amendments used and initial soils at field site are presented in the Tables II and III. Transplantation following subsequent protocols Basal doses of N, P2O5, and K2O from urea, TSP, and MoP fertilizers were applied at the rates of 40, 30, and 15 kg ha-1, respectively considering soil amendments and initial contents of the nutrients. During field preparation, the TSP, MoP, and half of the urea were applied in their entirety after being thoroughly mixed with the field soil. The remaining urea was top dressed in two splits, one at the beginning of the rice panicle and another at the active tillering stage. Three seedlings per hill of the BR 25 variety, which were thirty days old and in good health, were transplanted. Row to row and hill to hill distances were each 20 and 22 cm, respectively. No irrigation was required for this study for the growth of rice in this season. Intercultur- al operations such as, weeding, pesticide use, etc. were done as per requirement. Sample collection and analyses Plant samples were collected from each plot just after harvesting. Soil samples were collected from 3 spots as replications of each plot of active root zone (0-15 cm) with the help of an auger. Soil samples were then stored treatment wise in polythene bags with proper labeling. After sun drying and grounding the samples were then passed through 2 mm sieve and stored properly in air tight plastic pots for further analyses. The collected plant samples were sun dried and weighed. After sun drying a portion of the collected plant samples were oven dried at 65⁰C and then grinded and stored in air tight plastic pots for laboratory analyses. All the labora- tory analyses were done following standard methods. Statistical analyses Pearson correlation and regression analyses between treatments and mineral nutrition of rice plants, Analysis of Variance (ANOVA) and Tukey’s Range Test at 5% (p≤ 0.05) level were done for the interpretation of the experi- mental results. Results and discussion Mineral nutrition of rice plants The total nitrogen, phosphorus, potassium, sulfur, calcium and magnesium contents at maturity stage of rice plants grown under field condition were significantly (p≤0.05) influenced by the application of variable indigenous organic amendments (rice hull compost, rice straw compost, sawdust compost and vermicompost) during Aman season (Table IV and Fig.1). Pearson correlation and regression analyses have been performed between the different treatments and mineral nutrition of rice plant tissues (Table V). Significance has been determined based on p values whether they were <0.05 or not. The total nitrogen (r = 0.78***), phosphorus (r = 0.77**), potassium (r = 0.75**), sulfur (r = 0.82***), calcium (r = 0.82***) and magnesium (r = 0.60*) contents of the tested rice plant (BR 25) tissues were signifi- cantly correlated with the applied organic composts and these correlations confirmed that the different sources of organic materials positively influenced the nutrition of rice plant tissues which ultimately regulate the edible part (grain) of the rice crops. According to Graham et al. (2012), people taking cereal based diets still suffering from hidden hunger of nutrients due to low level and low bioavailability of essential elements. The present results demonstrated that the nitro- gen content in rice straw increased with the increased rate of the application of organic composts. The maximum nitrogen contents in the rice plant tissues were recorded at V8 treatment for the tested variety. Among the applied composts, vermicompost (18.63 g kg-1N) ranked first followed by rice straw compost (17.40 g kg-1), sawdust compost (14.57g kg-1) and rice hull compost (13.33 g kg-1), regardless of their doses. Phosphorus contents in rice plant tissues increased with the higher rates of the different composts. The highest (4.42 g kg-1) and lowest (1.10 g kg-1) contents of total phosphorus were recorded in the T12 (V8) and T0 (control) treatments. The rest of the above-men- tioned nutrients were exerted the similar trends as those obtained by the P and N contents by the different organic composts. The nutrition of rice shoots was influenced by the direction of vermicompost > rice straw compost > sawdust compost > rice hull compost for the studied variety of rice grown under field condition. Nutrient status of post-harvest soils Rice production during T. Aman season, the available N contents in the post-harvest soils increased significantly (p ≤ 0.05) by the application of vermicompost, rice hull compost, rice straw compost and sawdust compost (Table VI and Fig. 2). The maximum amount of available N (78.29 mg kg-1) was recorded in T3 (RHC8) treatment, where available nitrogen content increased 85.65% as compared to control plot. At the same dose (8 t ha-1), the sawdust compost treatment ranked second for the available nitrogen content (62.31 mg kg-1) at post-harvest soils followed by RSC8 treatment (60.76 mg kg-1). There were significant (p≤0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of the organic amendments under rice production (Table VI). Soils treated with vermicompost at the rate of 8 t ha-1 was found to have significantly more phosphorus (12.57 mg kg-1) as compared to control plot. The rice straw compost and sawdust compost each at 8 t ha-1 were showed almost similar trends in the increment of available phosphorus contents in post-harvest soils followed by rice hull compost. The other nutrients of post-harvest soils followed the similar trends as that of phosphorus, except for the exchangeable potassium, where rice straw compost at the highest rate (8 t ha-1) exhibit- ed the best response (0.97 c molc kg -1) than those of the other treatments. The maximum amounts of available sulfur, exchangeable calcium and magnesium were obtained from the highest dose of vermicompost and the minimum amounts were attained by the control plot. The trend of increments of all these nutrients were more pronounced with the higher rates of the applied organic amendments indicate that all the applied organic composts are suitable sources for improving nutrient statuses of soils. Pearson correlation and regression analyses also indicate the strong positive relationship between the treatments and nutrient statuses of post-harvest soils (Table VII). The current findings are in consistent with those of Xin et al. (2017). Many steps have been made to improve soil fertility and productivity, according to them. Increased organic input, such as organic manure, compost, and straw integration, are the most effective approaches. Crop straw, a cheap and nutrient-dense material, offers a lot of potential for enhancing soil fertility (Tan et al. 2017). Crop straw, which is high in nutrients and organic elements, can be treated as a natural organic fertilizer and utilized as an alternative to chemical fertilizers, according to the studies of Wang et al. (2017). As a result, straw integration appears to be a potential method for maintaining and restoring soil fertility, the burning issue of present day. Because, mineral elements are required for the healthy growth and development of both plants and humans. The plant roots take up the mineral nutrients from soil and transported them to the edible parts for human consumption through various transporters. For human health, an ideal future crop should be rich in essential mineral elements but with less toxic elements in the edible parts. Still, it is estimat- ed that nearly 2 billion people are suffering from deficiency of nutrients because of low availability of mineral elements in soil and/or low accumulation/bioavailability of mineral elements in edible parts (Graham et al. 2012). This so-called hidden hunger is an especially serious health problem for people subsisting on cereal-based diets because cereals such as rice usually contain a low level of mineral elements as well as low bioavailability (Grebmer et al. 2014; Nakandalage and Seneweera, 2018). On the other hand, rapid urbanization and industrialization cause contamination by toxic elements in many soils used for crop production (Zhao et al. 2010; Clemens and Ma, 2016), which threaten our health throughout the food chain. Therefore, it is extremely important to boost essential nutrients (both density and bioavailability) and reduce toxic elements in edible parts of cereals for human health. Conclusion The present research findings conclude that the locally made organic composts using indigenous organic materi- als had potential to improve soil fertility and provide nutrients for rice production. Significant positive correla- tion between the treatments and mineral nutrients of rice plants confirmed the strong relationship of organic farm- ing for sustainable agriculture. There were significant (p ≤ 0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of amendments under rice production. The nutrition of rice plants grown under field condition was influenced most by the vermi- compost and followed the order of the treatments as rice straw compost > sawdust compost > rice hull compost for the studied variety of rice. These results resemble that the further researches are needed to find out the suitable doses and types of the amendments. However, the applied organ- ic fertilizers were found to have responses on the nutri- tional statuses of rice shoot and post-harvest soils and these might be effective for the nutritional balance of the rice variety and ultimately will be helpful for country’s penniless people to combat their existing and future demand of quality rice. Acknowledgement The study was carried out under a project of the Climate Change Trust Fund (CCTF) titled ‘Assessment of Impacts of Climate Change on Soil Health and Food Security, and Adaptation of Climate-smart Agriculture in Most Adversely Affected Areas of Bangladesh’ through the MoEFCC, Government of the Peoples’ Republic of Bangladesh. The project was implemented in two phases (Phase I: Jan.’17 to Dec.’18, Code 410 DUand Phase II: Jan.’19 to Dec.’22, Code 573 DU) within six years. We are also grateful to the Project staff and relevant officers/staff of the SWED-DU, DU, MoE and MoEFCC of GoB, who performed for the successful completion of the study. References Ahmed S, Alam MJ, Hossain A, Islam AK, Awan TH, Soufan W, Qahtan AA, Okla MK and Sabagh SI (2021), Interactive effect of weeding regimes, rice cultivars, and seeding rates influence the rice-weed competition under dry direct-seeded condition, Sustainability. 13: 317-321. DOI: 10.3390/su13010317 Akter S and Khan HR (2019), Influence of rice hull, rice straw, sawdust and moisture levels on selected proper- ties of post harvested saline soils under variable condi- tions of rice cultivation, National University Journal of Science. 6(1): 61-74. Akter S, Khan HR, Hossain MS, Saha MK and Farzana F (2018), Response of rice grown in saline soil as influenced by the application of agricultural amend- ments and moisture regimes, J biodivers conserv bioresour manag. 4(2): 33-42. DOI: https://doi.org/ 10.3329/jbcbm.v4i2.39845 Ansari AA and Ismail SA (2012), Role of Earthworms in Vermtechnology, J Agric Technol. 8(2): 405-415. https://www.ijat-aatsea.com Arora VK, Singh CB, Sidhu AS and Thind SS (2011), Irriga- tion, tillage and mulching effects on Soybean yield and water productivity in relation to soil texture, Agric Water Manag. 98(4): 563-568. https://- doi.org/10.1016/j.agwat .2010.10.004 BBS (2017), Bangladesh Bureau of Statistics. The Year Book of Agricultural Statistics of Bangladesh. Stat. Div. Minis. Planning, Govt. Peoples Repub. Bangladesh, Dhaka. BBS (2020), Summary Crop Statistics and Crop Indices (2019-2020). Bangladesh Bureau of Statistics Division, Govt. of the People’s Republic of Bangla- desh: Dhaka, Bangladesh. pp 35-37. Chanda GC, Bhunia G and Chakraborty SK (2011), The effect of vermicompost and other fertilizers on cultiva- tion of Tomato plants, J Hortic For. 3: 42-45. http://w- ww.acade mic journals.org/jhf Clemens S and Ma JF (2016), Toxic heavy metal and metal- loid accumulation in crop plants and foods, Annu Rev Plant Biol. 67: 489-512. DOI: 10.1146/annurev-ar- plant-043015-112301 Dinesh R, Suryanarayana MA, Nair AK and Chaudhuri SG (2011), Leguminous cover crop effects on nitrogen mineralization rates and kinetics in soils, J Agron Crop Sci. 187: 161-166. DOI: 10.1046/j.1439-037x. 2001. 00512.x FRG (2012), (Fertilizer Recommendation Guide). Bangladesh Agricultural Research Council (BARC), Dhaka, Bangladesh. Graham RD, Knez M and Welch RM (2012), How much nutritional iron deficiency in humans globally is due to an underlying zinc deficiency, Adv Agron. 1-40. DOI: 10.1016/B978-0-12-394276-0.00001-9 Grebmer BKV, Saltzman A, Birol E, Wiesmann D, Prasai N, YinS, Yohannes Y, Menon P, Thompson J and Sonntag A (2014), 2014 Global Hunger Index: The Challenge of Hidden Hunger (Washington, DC: International Food Policy Research Institute), pp 56. DOI: http://dx- .doi.org/10.2499/9780896299580 Guerrero RD (2010), Vermicompost production and its use for crop production in the Philippines, International Journal of Global Environmental Issues. 10(3/4): 378-383. DOI: 10.1504/IJGENVI.2010.037278 Gurtler JB, Doyle MP, Erickson MC, Jiang X, Millner P and Sharma M (2018), Composting to inactivate food borne pathogens for crop soil application, A review J Food Prot.81: 1821-1837. DOI: 10.4315/0362-028X.- JFP-18-217 Heitkamp F, Raupp J and Ludwig B (2011), Soil organic matter pools and crop yields as affected by the rate of farmyard manure and use of biodynamic preparations in a sandy soil, Organic Agriculture. 11: 111-124. DOI: 10.1007/s13165-011-0010-7 Jahiruddin M and Satter MA (2010), Research priority in agriculture and development of vision document-2030 and beyond. Land and soil resource management. Bangladesh gricultural Research Council. Dhaka. Jeptoo A, Aguyoh JN and Saidi M (2013), Improving Carrot Yield and Quality through the Use of Bio-Slurry Manure, Sustainable Agricultural Research. 2(1): 164-172. DOI: 10.5539/sar.v2n1p164 Nakandalage N and Seneweera S (2018), Micronutrients useefficiency of crop-plants under changing climate. In Plant Micronutrient Use Efficiency, M.A. Hossain, T. Kamiya, D.J. Burritt, L.-S.P. Tran and T. Fujiwara, eds. (London: Academic Press), pp 209-224. Palaniveloo K, Amran MA, Norhashim NA, Mohamad-Fauzi N, Peng-Hui F, Hui-Wen L, Kai-Lin Y, Jiale L, Chian-Yee MG and Jing-Yi L (2020), Food Waste Composting and Microbial Community Structure Profiling, Processes. 8: 723. DOI: org/10.3390/ pr8060723 Partey ST, Thevathasan NV, Zougmoré RB and Preziosi RF (2018), Improving maize production through nitrogen supply from tenrarely-used organic resources in Ghana, Agrofor Syst. 92: 375-387. DOI: 10.1007/ s10457-016-0035-8 Pituello C, Polese R, Morari F and Berti A (2016), Outcomes from a long-term study on crop residue effects on plant yield and nitrogen use efficiency in contrasting soils, Eur J Agron. 77: 179-187. DOI: 10.1016/j. eja.2015.11.027 Somerville PD, Farrell C, May PB and Livesley SJ (2020), Biochar and compost equally improve urban soil physical and biological properties and tree growth, with no added benefit in combination, Sci Total Environ. 706: 135-736. DOI: 10.1016/j.scitotenv. 2019.135736 Tan D, Liu Z, Jiang L, Luo J and Li J (2017), Long-term potash application and wheat straw return reduced soil potassium fixation and affected crop yields in North China, Nutr Cycl Agroecosyst. DOI: 10.1007/s10705- 017-9843-0 Wang W, Sardans J, Wang C, Pan T, Zeng C, Lai D, Bartrons M and Peñuelas J (2017), Straw Application Strategy to Optimize Nutrient Release in a Southeastern China Rice Cropland, Agronomy. 7. DOI: 10.3390/agronomy 7040084 Xin X, Qin S, Zhang J, Zhu A, Yang W and Zhang X (2017), Yield, phosphorus use efficiency and balance response to substituting long-term chemical fertilizer use with organic manure in a wheat-maize system, Field Crop Res. 208: 27-33. DOI: 10.1016/j.fcr.2017.03.011 Yang HS, Xu MM, Koide RT, Liu Q, Dai YJ, Liu L and Bian XM (2016), Effects of ditch-buried straw return on water percolation, nitrogen leaching and crop yields in a rice-wheat rotation system, J Sc. Food Agric. 96: 1141-1149. DOI: 10.1002/jsfa.7196 Zhang P, Chen X, Wei T, Yang Z, Jia Z, Yang B, Han Q and Ren X (2016), Effects of straw incorporation on the soil nutrient contents, enzyme activities, and crop yield in a semiarid region of China, Soil Tillage Res. 160: 65-72. DOI: 10.1016/j.still.2016.02.006 Zhang Y, Liu Y, Zhang G, Guo X, Sun Z and Li T (2018), The Effects of Rice Straw and Biochar Applications on the Microbial Community in a Soil with a History of Continuous Tomato Planting History, Agronomy. 8. DOI: 10.3390/agronomy8050065 Zhao FJ, McGrath SP and Meharg AA (2010), Arsenic as a food chain contaminant: mechanisms of plant uptake and metabolism and mitigation strategies, Annu Rev Plant Biol. 61: 535-559. DOI: 10.1146/annurev-ar- plant-042809-112152 Table VII. Correlation between the treatments and nutrient statuses of post-harvest soils Nutrition Coefficient Stand. Error t Stat P-value Lower 95% Upper 95% *Av. Nitrogen 2.4323 0.5879 4.1374 0.0017 1.1384 3.7262 Av. Phosphorus 0.4720 0.0719 6.5611 0.0000 0.3137 0.6304 #Ex. Potassium 0.0802 0.0116 6.9098 0.0000 0.0546 0.1057 Av. Sulphur 0.4750 0.1822 2.6076 0.0244 0.0741 0.8760 Ex. Calcium 0.3347 0.0526 6.3628 0.0001 0.2189 0.4504 Ex. Magnesium 0.1550 0.0188 8.2649 0.0000 0.1137 0.1962 *Av. Indicate available and #Ex. Indicate exchangeable. However, until now, the use of straw incorporation to increase crop yield is still a matter of argument since studies in different climates and soil types have led to inconclusive results (Pituello et al. 2016). It has been reported that straw incorporation has significant valuable effects on crop yields and soil properties. For instance, straw incorporation can increase crop yields (Yang et al. 2016), soil organic matter and other soil nutrients (Zhang et al. 2018). Straw return can also improve soil physical properties, such as by increasing hydraulic conductivity, decreasing bulk density, and enhancing aggregate forma- tion (Yang et al. 2016). Vermicompost is a nourishing organic fertilizer having high amount of humus, nitrogen 2–3%, phosphorous 1.55–2.25%, potassium 1.85–2.25%, micronutrients, more beneficial for soil microbes like ‘nitrogen fixing bacteria’ and mycorrhizal fungi. Vermicompost has been scientifically proved as miracle plant growth enhancer (Guerrero, 2010). Ansari and Ismail (2012) reported that worms vermicompost contains 7.37 % nitrogen and 19.58% phosphorous as P2O5. Microbial population of N2- fixing bacteria and actinomycetes increases by the application of vermicompost. The amplified microbial activities improve the availability of soil phosphorous and nitrogen. Vermicomposting is an aerobic, biological method and is proficient to convert eco-friendly hummus like organic substances (Chanda et al. 2011). Vermicompost stimulates to influence the microbial activity of soil, increases the availability of oxygen, maintains normal soil temperature, increases soil porosity and infiltration of water, improves nutrient content and increases growth, yield and quality of the plant (Arora et al. 2011). Rice hull and sawdust are also important agricultural amendments. Growth and yield components of rice grown in saline soil were found to be increased significantly (p ≤ 0.05) by the application of rice hull, rice straw and sawdust alone and in combination (Akter et al. 2018). The physico-chemical properties and nutrient status of post-harvest soils were also found to be influenced by the application of these amendments (Akter and Khan, 2019). Composting is a low-cost natural way of recycling and stabilizing organic matter under thermophilic temperature that forms a pathogen-free substrate, beneficial to crops (Gurtler et al. 2018; Somerville et al. 2020). Low-income farmers found it more advantageous to them. Composting was found to be a promising practice that brought organic materials to a certain stage by narrowing down its C:N ratio where nutrients are easily accessible to plants (Palaniveloo et al. 2020). Partey et al. (2018) and Dinesh et al. (2011), had consolidated that biomass needs to decompose for making N available to crops. Thus, composting locally available organic amendments (OAs) is essential for a healthy and sustainable agro-ecosystem in different climatic conditions. Therefore, the objectives of the study were to evaluate the nutrient statuses of post-harvest soils and rice plants grown in Aman season as influenced by the different rates of organic composts applied under field condition. Materials and methods Study site and experimental design In Patuakhali a district of Bangladesh, the field experiment was conducted in Bilbilash of Bauphal Upazila (Map I), which is located between 22°20ʹ00ʺN and 90°20ʹ00ʺE longitude within agro-ecological zone-13 named as Ganges Tidal Floodplain. The climatic condition of this area is usually known as ‘tropical monsoon climate’. The area mainly enjoys three seasons such as rainy, dry and summer season. The experiment was carried out following completely randomized block design with the self-made organic composts, such as, Rice Hull Compost (RHC), Rice Straw Compost (RSC), Sawdust Compost (SDC) and Vermicompost (V) corresponding to the rates of 0, 2, 4 and 8 t ha-1 of each organic compost at Aman season during August to December, 2018. There were 13 plots having individual treatment (Table I) in the experimental area, each unit plot size was 16 m2 (4m×4m) and replications were considered within the plot. Selected properties of potential amendments used and initial soils at field site are presented in the Tables II and III. Transplantation following subsequent protocols Basal doses of N, P2O5, and K2O from urea, TSP, and MoP fertilizers were applied at the rates of 40, 30, and 15 kg ha-1, respectively considering soil amendments and initial contents of the nutrients. During field preparation, the TSP, MoP, and half of the urea were applied in their entirety after being thoroughly mixed with the field soil. The remaining urea was top dressed in two splits, one at the beginning of the rice panicle and another at the active tillering stage. Three seedlings per hill of the BR 25 variety, which were thirty days old and in good health, were transplanted. Row to row and hill to hill distances were each 20 and 22 cm, respectively. No irrigation was required for this study for the growth of rice in this season. Intercultur- al operations such as, weeding, pesticide use, etc. were done as per requirement. Sample collection and analyses Plant samples were collected from each plot just after harvesting. Soil samples were collected from 3 spots as replications of each plot of active root zone (0-15 cm) with the help of an auger. Soil samples were then stored treatment wise in polythene bags with proper labeling. After sun drying and grounding the samples were then passed through 2 mm sieve and stored properly in air tight plastic pots for further analyses. The collected plant samples were sun dried and weighed. After sun drying a portion of the collected plant samples were oven dried at 65⁰C and then grinded and stored in air tight plastic pots for laboratory analyses. All the labora- tory analyses were done following standard methods. Statistical analyses Pearson correlation and regression analyses between treatments and mineral nutrition of rice plants, Analysis of Variance (ANOVA) and Tukey’s Range Test at 5% (p≤ 0.05) level were done for the interpretation of the experi- mental results. Results and discussion Mineral nutrition of rice plants The total nitrogen, phosphorus, potassium, sulfur, calcium and magnesium contents at maturity stage of rice plants grown under field condition were significantly (p≤0.05) influenced by the application of variable indigenous organic amendments (rice hull compost, rice straw compost, sawdust compost and vermicompost) during Aman season (Table IV and Fig.1). Pearson correlation and regression analyses have been performed between the different treatments and mineral nutrition of rice plant tissues (Table V). Significance has been determined based on p values whether they were <0.05 or not. The total nitrogen (r = 0.78***), phosphorus (r = 0.77**), potassium (r = 0.75**), sulfur (r = 0.82***), calcium (r = 0.82***) and magnesium (r = 0.60*) contents of the tested rice plant (BR 25) tissues were signifi- cantly correlated with the applied organic composts and these correlations confirmed that the different sources of organic materials positively influenced the nutrition of rice plant tissues which ultimately regulate the edible part (grain) of the rice crops. According to Graham et al. (2012), people taking cereal based diets still suffering from hidden hunger of nutrients due to low level and low bioavailability of essential elements. The present results demonstrated that the nitro- gen content in rice straw increased with the increased rate of the application of organic composts. The maximum nitrogen contents in the rice plant tissues were recorded at V8 treatment for the tested variety. Among the applied composts, vermicompost (18.63 g kg-1N) ranked first followed by rice straw compost (17.40 g kg-1), sawdust compost (14.57g kg-1) and rice hull compost (13.33 g kg-1), regardless of their doses. Phosphorus contents in rice plant tissues increased with the higher rates of the different composts. The highest (4.42 g kg-1) and lowest (1.10 g kg-1) contents of total phosphorus were recorded in the T12 (V8) and T0 (control) treatments. The rest of the above-men- tioned nutrients were exerted the similar trends as those obtained by the P and N contents by the different organic composts. The nutrition of rice shoots was influenced by the direction of vermicompost > rice straw compost > sawdust compost > rice hull compost for the studied variety of rice grown under field condition. Nutrient status of post-harvest soils Rice production during T. Aman season, the available N contents in the post-harvest soils increased significantly (p ≤ 0.05) by the application of vermicompost, rice hull compost, rice straw compost and sawdust compost (Table VI and Fig. 2). The maximum amount of available N (78.29 mg kg-1) was recorded in T3 (RHC8) treatment, where available nitrogen content increased 85.65% as compared to control plot. At the same dose (8 t ha-1), the sawdust compost treatment ranked second for the available nitrogen content (62.31 mg kg-1) at post-harvest soils followed by RSC8 treatment (60.76 mg kg-1). There were significant (p≤0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of the organic amendments under rice production (Table VI). Soils treated with vermicompost at the rate of 8 t ha-1 was found to have significantly more phosphorus (12.57 mg kg-1) as compared to control plot. The rice straw compost and sawdust compost each at 8 t ha-1 were showed almost similar trends in the increment of available phosphorus contents in post-harvest soils followed by rice hull compost. The other nutrients of post-harvest soils followed the similar trends as that of phosphorus, except for the exchangeable potassium, where rice straw compost at the highest rate (8 t ha-1) exhibit- ed the best response (0.97 c molc kg -1) than those of the other treatments. The maximum amounts of available sulfur, exchangeable calcium and magnesium were obtained from the highest dose of vermicompost and the minimum amounts were attained by the control plot. The trend of increments of all these nutrients were more pronounced with the higher rates of the applied organic amendments indicate that all the applied organic composts are suitable sources for improving nutrient statuses of soils. Pearson correlation and regression analyses also indicate the strong positive relationship between the treatments and nutrient statuses of post-harvest soils (Table VII). The current findings are in consistent with those of Xin et al. (2017). Many steps have been made to improve soil fertility and productivity, according to them. Increased organic input, such as organic manure, compost, and straw integration, are the most effective approaches. Crop straw, a cheap and nutrient-dense material, offers a lot of potential for enhancing soil fertility (Tan et al. 2017). Crop straw, which is high in nutrients and organic elements, can be treated as a natural organic fertilizer and utilized as an alternative to chemical fertilizers, according to the studies of Wang et al. (2017). As a result, straw integration appears to be a potential method for maintaining and restoring soil fertility, the burning issue of present day. Because, mineral elements are required for the healthy growth and development of both plants and humans. The plant roots take up the mineral nutrients from soil and transported them to the edible parts for human consumption through various transporters. For human health, an ideal future crop should be rich in essential mineral elements but with less toxic elements in the edible parts. Still, it is estimat- ed that nearly 2 billion people are suffering from deficiency of nutrients because of low availability of mineral elements in soil and/or low accumulation/bioavailability of mineral elements in edible parts (Graham et al. 2012). This so-called hidden hunger is an especially serious health problem for people subsisting on cereal-based diets because cereals such as rice usually contain a low level of mineral elements as well as low bioavailability (Grebmer et al. 2014; Nakandalage and Seneweera, 2018). On the other hand, rapid urbanization and industrialization cause contamination by toxic elements in many soils used for crop production (Zhao et al. 2010; Clemens and Ma, 2016), which threaten our health throughout the food chain. Therefore, it is extremely important to boost essential nutrients (both density and bioavailability) and reduce toxic elements in edible parts of cereals for human health. Conclusion The present research findings conclude that the locally made organic composts using indigenous organic materi- als had potential to improve soil fertility and provide nutrients for rice production. Significant positive correla- tion between the treatments and mineral nutrients of rice plants confirmed the strong relationship of organic farm- ing for sustainable agriculture. There were significant (p ≤ 0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of amendments under rice production. The nutrition of rice plants grown under field condition was influenced most by the vermi- compost and followed the order of the treatments as rice straw compost > sawdust compost > rice hull compost for the studied variety of rice. These results resemble that the further researches are needed to find out the suitable doses and types of the amendments. However, the applied organ- ic fertilizers were found to have responses on the nutri- tional statuses of rice shoot and post-harvest soils and these might be effective for the nutritional balance of the rice variety and ultimately will be helpful for country’s penniless people to combat their existing and future demand of quality rice. Acknowledgement The study was carried out under a project of the Climate Change Trust Fund (CCTF) titled ‘Assessment of Impacts of Climate Change on Soil Health and Food Security, and Adaptation of Climate-smart Agriculture in Most Adversely Affected Areas of Bangladesh’ through the MoEFCC, Government of the Peoples’ Republic of Bangladesh. The project was implemented in two phases (Phase I: Jan.’17 to Dec.’18, Code 410 DUand Phase II: Jan.’19 to Dec.’22, Code 573 DU) within six years. We are also grateful to the Project staff and relevant officers/staff of the SWED-DU, DU, MoE and MoEFCC of GoB, who performed for the successful completion of the study. References Ahmed S, Alam MJ, Hossain A, Islam AK, Awan TH, Soufan W, Qahtan AA, Okla MK and Sabagh SI (2021), Interactive effect of weeding regimes, rice cultivars, and seeding rates influence the rice-weed competition under dry direct-seeded condition, Sustainability. 13: 317-321. DOI: 10.3390/su13010317 Akter S and Khan HR (2019), Influence of rice hull, rice straw, sawdust and moisture levels on selected proper- ties of post harvested saline soils under variable condi- tions of rice cultivation, National University Journal of Science. 6(1): 61-74. Akter S, Khan HR, Hossain MS, Saha MK and Farzana F (2018), Response of rice grown in saline soil as influenced by the application of agricultural amend- ments and moisture regimes, J biodivers conserv bioresour manag. 4(2): 33-42. DOI: https://doi.org/ 10.3329/jbcbm.v4i2.39845 Ansari AA and Ismail SA (2012), Role of Earthworms in Vermtechnology, J Agric Technol. 8(2): 405-415. https://www.ijat-aatsea.com Arora VK, Singh CB, Sidhu AS and Thind SS (2011), Irriga- tion, tillage and mulching effects on Soybean yield and water productivity in relation to soil texture, Agric Water Manag. 98(4): 563-568. https://- doi.org/10.1016/j.agwat .2010.10.004 BBS (2017), Bangladesh Bureau of Statistics. The Year Book of Agricultural Statistics of Bangladesh. Stat. Div. Minis. Planning, Govt. Peoples Repub. Bangladesh, Dhaka. BBS (2020), Summary Crop Statistics and Crop Indices (2019-2020). Bangladesh Bureau of Statistics Division, Govt. of the People’s Republic of Bangla- desh: Dhaka, Bangladesh. pp 35-37. Chanda GC, Bhunia G and Chakraborty SK (2011), The effect of vermicompost and other fertilizers on cultiva- tion of Tomato plants, J Hortic For. 3: 42-45. http://w- ww.acade mic journals.org/jhf Clemens S and Ma JF (2016), Toxic heavy metal and metal- loid accumulation in crop plants and foods, Annu Rev Plant Biol. 67: 489-512. DOI: 10.1146/annurev-ar- plant-043015-112301 Dinesh R, Suryanarayana MA, Nair AK and Chaudhuri SG (2011), Leguminous cover crop effects on nitrogen mineralization rates and kinetics in soils, J Agron Crop Sci. 187: 161-166. DOI: 10.1046/j.1439-037x. 2001. 00512.x FRG (2012), (Fertilizer Recommendation Guide). Bangladesh Agricultural Research Council (BARC), Dhaka, Bangladesh. Graham RD, Knez M and Welch RM (2012), How much nutritional iron deficiency in humans globally is due to an underlying zinc deficiency, Adv Agron. 1-40. DOI: 10.1016/B978-0-12-394276-0.00001-9 Grebmer BKV, Saltzman A, Birol E, Wiesmann D, Prasai N, YinS, Yohannes Y, Menon P, Thompson J and Sonntag A (2014), 2014 Global Hunger Index: The Challenge of Hidden Hunger (Washington, DC: International Food Policy Research Institute), pp 56. DOI: http://dx- .doi.org/10.2499/9780896299580 Guerrero RD (2010), Vermicompost production and its use for crop production in the Philippines, International Journal of Global Environmental Issues. 10(3/4): 378-383. DOI: 10.1504/IJGENVI.2010.037278 Gurtler JB, Doyle MP, Erickson MC, Jiang X, Millner P and Sharma M (2018), Composting to inactivate food borne pathogens for crop soil application, A review J Food Prot.81: 1821-1837. DOI: 10.4315/0362-028X.- JFP-18-217 Heitkamp F, Raupp J and Ludwig B (2011), Soil organic matter pools and crop yields as affected by the rate of farmyard manure and use of biodynamic preparations in a sandy soil, Organic Agriculture. 11: 111-124. DOI: 10.1007/s13165-011-0010-7 Jahiruddin M and Satter MA (2010), Research priority in agriculture and development of vision document-2030 and beyond. Land and soil resource management. Bangladesh gricultural Research Council. Dhaka. Jeptoo A, Aguyoh JN and Saidi M (2013), Improving Carrot Yield and Quality through the Use of Bio-Slurry Manure, Sustainable Agricultural Research. 2(1): 164-172. DOI: 10.5539/sar.v2n1p164 Nakandalage N and Seneweera S (2018), Micronutrients useefficiency of crop-plants under changing climate. In Plant Micronutrient Use Efficiency, M.A. Hossain, T. Kamiya, D.J. Burritt, L.-S.P. Tran and T. Fujiwara, eds. (London: Academic Press), pp 209-224. Palaniveloo K, Amran MA, Norhashim NA, Mohamad-Fauzi N, Peng-Hui F, Hui-Wen L, Kai-Lin Y, Jiale L, Chian-Yee MG and Jing-Yi L (2020), Food Waste Composting and Microbial Community Structure Profiling, Processes. 8: 723. DOI: org/10.3390/ pr8060723 Partey ST, Thevathasan NV, Zougmoré RB and Preziosi RF (2018), Improving maize production through nitrogen supply from tenrarely-used organic resources in Ghana, Agrofor Syst. 92: 375-387. DOI: 10.1007/ s10457-016-0035-8 Pituello C, Polese R, Morari F and Berti A (2016), Outcomes from a long-term study on crop residue effects on plant yield and nitrogen use efficiency in contrasting soils, Eur J Agron. 77: 179-187. DOI: 10.1016/j. eja.2015.11.027 Somerville PD, Farrell C, May PB and Livesley SJ (2020), Biochar and compost equally improve urban soil physical and biological properties and tree growth, with no added benefit in combination, Sci Total Environ. 706: 135-736. DOI: 10.1016/j.scitotenv. 2019.135736 Tan D, Liu Z, Jiang L, Luo J and Li J (2017), Long-term potash application and wheat straw return reduced soil potassium fixation and affected crop yields in North China, Nutr Cycl Agroecosyst. DOI: 10.1007/s10705- 017-9843-0 Wang W, Sardans J, Wang C, Pan T, Zeng C, Lai D, Bartrons M and Peñuelas J (2017), Straw Application Strategy to Optimize Nutrient Release in a Southeastern China Rice Cropland, Agronomy. 7. DOI: 10.3390/agronomy 7040084 Xin X, Qin S, Zhang J, Zhu A, Yang W and Zhang X (2017), Yield, phosphorus use efficiency and balance response to substituting long-term chemical fertilizer use with organic manure in a wheat-maize system, Field Crop Res. 208: 27-33. DOI: 10.1016/j.fcr.2017.03.011 Yang HS, Xu MM, Koide RT, Liu Q, Dai YJ, Liu L and Bian XM (2016), Effects of ditch-buried straw return on water percolation, nitrogen leaching and crop yields in a rice-wheat rotation system, J Sc. Food Agric. 96: 1141-1149. DOI: 10.1002/jsfa.7196 Zhang P, Chen X, Wei T, Yang Z, Jia Z, Yang B, Han Q and Ren X (2016), Effects of straw incorporation on the soil nutrient contents, enzyme activities, and crop yield in a semiarid region of China, Soil Tillage Res. 160: 65-72. DOI: 10.1016/j.still.2016.02.006 Zhang Y, Liu Y, Zhang G, Guo X, Sun Z and Li T (2018), The Effects of Rice Straw and Biochar Applications on the Microbial Community in a Soil with a History of Continuous Tomato Planting History, Agronomy. 8. DOI: 10.3390/agronomy8050065 Zhao FJ, McGrath SP and Meharg AA (2010), Arsenic as a food chain contaminant: mechanisms of plant uptake and metabolism and mitigation strategies, Annu Rev Plant Biol. 61: 535-559. DOI: 10.1146/annurev-ar- plant-042809-112152 Hasan, Satter and Ahmed 105 However, until now, the use of straw incorporation to increase crop yield is still a matter of argument since studies in different climates and soil types have led to inconclusive results (Pituello et al. 2016). It has been reported that straw incorporation has significant valuable effects on crop yields and soil properties. For instance, straw incorporation can increase crop yields (Yang et al. 2016), soil organic matter and other soil nutrients (Zhang et al. 2018). Straw return can also improve soil physical properties, such as by increasing hydraulic conductivity, decreasing bulk density, and enhancing aggregate forma- tion (Yang et al. 2016). Vermicompost is a nourishing organic fertilizer having high amount of humus, nitrogen 2–3%, phosphorous 1.55–2.25%, potassium 1.85–2.25%, micronutrients, more beneficial for soil microbes like ‘nitrogen fixing bacteria’ and mycorrhizal fungi. Vermicompost has been scientifically proved as miracle plant growth enhancer (Guerrero, 2010). Ansari and Ismail (2012) reported that worms vermicompost contains 7.37 % nitrogen and 19.58% phosphorous as P2O5. Microbial population of N2- fixing bacteria and actinomycetes increases by the application of vermicompost. The amplified microbial activities improve the availability of soil phosphorous and nitrogen. Vermicomposting is an aerobic, biological method and is proficient to convert eco-friendly hummus like organic substances (Chanda et al. 2011). Vermicompost stimulates to influence the microbial activity of soil, increases the availability of oxygen, maintains normal soil temperature, increases soil porosity and infiltration of water, improves nutrient content and increases growth, yield and quality of the plant (Arora et al. 2011). Rice hull and sawdust are also important agricultural amendments. Growth and yield components of rice grown in saline soil were found to be increased significantly (p ≤ 0.05) by the application of rice hull, rice straw and sawdust alone and in combination (Akter et al. 2018). The physico-chemical properties and nutrient status of post-harvest soils were also found to be influenced by the application of these amendments (Akter and Khan, 2019). Composting is a low-cost natural way of recycling and stabilizing organic matter under thermophilic temperature that forms a pathogen-free substrate, beneficial to crops (Gurtler et al. 2018; Somerville et al. 2020). Low-income farmers found it more advantageous to them. Composting was found to be a promising practice that brought organic materials to a certain stage by narrowing down its C:N ratio where nutrients are easily accessible to plants (Palaniveloo et al. 2020). Partey et al. (2018) and Dinesh et al. (2011), had consolidated that biomass needs to decompose for making N available to crops. Thus, composting locally available organic amendments (OAs) is essential for a healthy and sustainable agro-ecosystem in different climatic conditions. Therefore, the objectives of the study were to evaluate the nutrient statuses of post-harvest soils and rice plants grown in Aman season as influenced by the different rates of organic composts applied under field condition. Materials and methods Study site and experimental design In Patuakhali a district of Bangladesh, the field experiment was conducted in Bilbilash of Bauphal Upazila (Map I), which is located between 22°20ʹ00ʺN and 90°20ʹ00ʺE longitude within agro-ecological zone-13 named as Ganges Tidal Floodplain. The climatic condition of this area is usually known as ‘tropical monsoon climate’. The area mainly enjoys three seasons such as rainy, dry and summer season. The experiment was carried out following completely randomized block design with the self-made organic composts, such as, Rice Hull Compost (RHC), Rice Straw Compost (RSC), Sawdust Compost (SDC) and Vermicompost (V) corresponding to the rates of 0, 2, 4 and 8 t ha-1 of each organic compost at Aman season during August to December, 2018. There were 13 plots having individual treatment (Table I) in the experimental area, each unit plot size was 16 m2 (4m×4m) and replications were considered within the plot. Selected properties of potential amendments used and initial soils at field site are presented in the Tables II and III. Transplantation following subsequent protocols Basal doses of N, P2O5, and K2O from urea, TSP, and MoP fertilizers were applied at the rates of 40, 30, and 15 kg ha-1, respectively considering soil amendments and initial contents of the nutrients. During field preparation, the TSP, MoP, and half of the urea were applied in their entirety after being thoroughly mixed with the field soil. The remaining urea was top dressed in two splits, one at the beginning of the rice panicle and another at the active tillering stage. Three seedlings per hill of the BR 25 variety, which were thirty days old and in good health, were transplanted. Row to row and hill to hill distances were each 20 and 22 cm, respectively. No irrigation was required for this study for the growth of rice in this season. Intercultur- al operations such as, weeding, pesticide use, etc. were done as per requirement. Sample collection and analyses Plant samples were collected from each plot just after harvesting. Soil samples were collected from 3 spots as replications of each plot of active root zone (0-15 cm) with the help of an auger. Soil samples were then stored treatment wise in polythene bags with proper labeling. After sun drying and grounding the samples were then passed through 2 mm sieve and stored properly in air tight plastic pots for further analyses. The collected plant samples were sun dried and weighed. After sun drying a portion of the collected plant samples were oven dried at 65⁰C and then grinded and stored in air tight plastic pots for laboratory analyses. All the labora- tory analyses were done following standard methods. Statistical analyses Pearson correlation and regression analyses between treatments and mineral nutrition of rice plants, Analysis of Variance (ANOVA) and Tukey’s Range Test at 5% (p≤ 0.05) level were done for the interpretation of the experi- mental results. Results and discussion Mineral nutrition of rice plants The total nitrogen, phosphorus, potassium, sulfur, calcium and magnesium contents at maturity stage of rice plants grown under field condition were significantly (p≤0.05) influenced by the application of variable indigenous organic amendments (rice hull compost, rice straw compost, sawdust compost and vermicompost) during Aman season (Table IV and Fig.1). Pearson correlation and regression analyses have been performed between the different treatments and mineral nutrition of rice plant tissues (Table V). Significance has been determined based on p values whether they were <0.05 or not. The total nitrogen (r = 0.78***), phosphorus (r = 0.77**), potassium (r = 0.75**), sulfur (r = 0.82***), calcium (r = 0.82***) and magnesium (r = 0.60*) contents of the tested rice plant (BR 25) tissues were signifi- cantly correlated with the applied organic composts and these correlations confirmed that the different sources of organic materials positively influenced the nutrition of rice plant tissues which ultimately regulate the edible part (grain) of the rice crops. According to Graham et al. (2012), people taking cereal based diets still suffering from hidden hunger of nutrients due to low level and low bioavailability of essential elements. The present results demonstrated that the nitro- gen content in rice straw increased with the increased rate of the application of organic composts. The maximum nitrogen contents in the rice plant tissues were recorded at V8 treatment for the tested variety. Among the applied composts, vermicompost (18.63 g kg-1N) ranked first followed by rice straw compost (17.40 g kg-1), sawdust compost (14.57g kg-1) and rice hull compost (13.33 g kg-1), regardless of their doses. Phosphorus contents in rice plant tissues increased with the higher rates of the different composts. The highest (4.42 g kg-1) and lowest (1.10 g kg-1) contents of total phosphorus were recorded in the T12 (V8) and T0 (control) treatments. The rest of the above-men- tioned nutrients were exerted the similar trends as those obtained by the P and N contents by the different organic composts. The nutrition of rice shoots was influenced by the direction of vermicompost > rice straw compost > sawdust compost > rice hull compost for the studied variety of rice grown under field condition. Nutrient status of post-harvest soils Rice production during T. Aman season, the available N contents in the post-harvest soils increased significantly (p ≤ 0.05) by the application of vermicompost, rice hull compost, rice straw compost and sawdust compost (Table VI and Fig. 2). The maximum amount of available N (78.29 mg kg-1) was recorded in T3 (RHC8) treatment, where available nitrogen content increased 85.65% as compared to control plot. At the same dose (8 t ha-1), the sawdust compost treatment ranked second for the available nitrogen content (62.31 mg kg-1) at post-harvest soils followed by RSC8 treatment (60.76 mg kg-1). There were significant (p≤0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of the organic amendments under rice production (Table VI). Soils treated with vermicompost at the rate of 8 t ha-1 was found to have significantly more phosphorus (12.57 mg kg-1) as compared to control plot. The rice straw compost and sawdust compost each at 8 t ha-1 were showed almost similar trends in the increment of available phosphorus contents in post-harvest soils followed by rice hull compost. The other nutrients of post-harvest soils followed the similar trends as that of phosphorus, except for the exchangeable potassium, where rice straw compost at the highest rate (8 t ha-1) exhibit- ed the best response (0.97 c molc kg -1) than those of the other treatments. The maximum amounts of available sulfur, exchangeable calcium and magnesium were obtained from the highest dose of vermicompost and the minimum amounts were attained by the control plot. The trend of increments of all these nutrients were more pronounced with the higher rates of the applied organic amendments indicate that all the applied organic composts are suitable sources for improving nutrient statuses of soils. Pearson correlation and regression analyses also indicate the strong positive relationship between the treatments and nutrient statuses of post-harvest soils (Table VII). The current findings are in consistent with those of Xin et al. (2017). Many steps have been made to improve soil fertility and productivity, according to them. Increased organic input, such as organic manure, compost, and straw integration, are the most effective approaches. Crop straw, a cheap and nutrient-dense material, offers a lot of potential for enhancing soil fertility (Tan et al. 2017). Crop straw, which is high in nutrients and organic elements, can be treated as a natural organic fertilizer and utilized as an alternative to chemical fertilizers, according to the studies of Wang et al. (2017). As a result, straw integration appears to be a potential method for maintaining and restoring soil fertility, the burning issue of present day. Because, mineral elements are required for the healthy growth and development of both plants and humans. The plant roots take up the mineral nutrients from soil and transported them to the edible parts for human consumption through various transporters. For human health, an ideal future crop should be rich in essential mineral elements but with less toxic elements in the edible parts. Still, it is estimat- ed that nearly 2 billion people are suffering from deficiency of nutrients because of low availability of mineral elements in soil and/or low accumulation/bioavailability of mineral elements in edible parts (Graham et al. 2012). This so-called hidden hunger is an especially serious health problem for people subsisting on cereal-based diets because cereals such as rice usually contain a low level of mineral elements as well as low bioavailability (Grebmer et al. 2014; Nakandalage and Seneweera, 2018). On the other hand, rapid urbanization and industrialization cause contamination by toxic elements in many soils used for crop production (Zhao et al. 2010; Clemens and Ma, 2016), which threaten our health throughout the food chain. Therefore, it is extremely important to boost essential nutrients (both density and bioavailability) and reduce toxic elements in edible parts of cereals for human health. Conclusion The present research findings conclude that the locally made organic composts using indigenous organic materi- als had potential to improve soil fertility and provide nutrients for rice production. Significant positive correla- tion between the treatments and mineral nutrients of rice plants confirmed the strong relationship of organic farm- ing for sustainable agriculture. There were significant (p ≤ 0.05) increase in available phosphorus and sulfur, exchangeable potassium, calcium and magnesium at post-harvest soils with the increased doses of amendments under rice production. The nutrition of rice plants grown under field condition was influenced most by the vermi- compost and followed the order of the treatments as rice straw compost > sawdust compost > rice hull compost for the studied variety of rice. These results resemble that the further researches are needed to find out the suitable doses and types of the amendments. However, the applied organ- ic fertilizers were found to have responses on the nutri- tional statuses of rice shoot and post-harvest soils and these might be effective for the nutritional balance of the rice variety and ultimately will be helpful for country’s penniless people to combat their existing and future demand of quality rice. Acknowledgement The study was carried out under a project of the Climate Change Trust Fund (CCTF) titled ‘Assessment of Impacts of Climate Change on Soil Health and Food Security, and Adaptation of Climate-smart Agriculture in Most Adversely Affected Areas of Bangladesh’ through the MoEFCC, Government of the Peoples’ Republic of Bangladesh. The project was implemented in two phases (Phase I: Jan.’17 to Dec.’18, Code 410 DUand Phase II: Jan.’19 to Dec.’22, Code 573 DU) within six years. We are also grateful to the Project staff and relevant officers/staff of the SWED-DU, DU, MoE and MoEFCC of GoB, who performed for the successful completion of the study. References Ahmed S, Alam MJ, Hossain A, Islam AK, Awan TH, Soufan W, Qahtan AA, Okla MK and Sabagh SI (2021), Interactive effect of weeding regimes, rice cultivars, and seeding rates influence the rice-weed competition under dry direct-seeded condition, Sustainability. 13: 317-321. DOI: 10.3390/su13010317 Akter S and Khan HR (2019), Influence of rice hull, rice straw, sawdust and moisture levels on selected proper- ties of post harvested saline soils under variable condi- tions of rice cultivation, National University Journal of Science. 6(1): 61-74. Akter S, Khan HR, Hossain MS, Saha MK and Farzana F (2018), Response of rice grown in saline soil as influenced by the application of agricultural amend- ments and moisture regimes, J biodivers conserv bioresour manag. 4(2): 33-42. DOI: https://doi.org/ 10.3329/jbcbm.v4i2.39845 Ansari AA and Ismail SA (2012), Role of Earthworms in Vermtechnology, J Agric Technol. 8(2): 405-415. https://www.ijat-aatsea.com Arora VK, Singh CB, Sidhu AS and Thind SS (2011), Irriga- tion, tillage and mulching effects on Soybean yield and water productivity in relation to soil texture, Agric Water Manag. 98(4): 563-568. https://- doi.org/10.1016/j.agwat .2010.10.004 BBS (2017), Bangladesh Bureau of Statistics. 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