Bangladesh Agron. J. 2015, 18(2): 39-44 RESPONSE OF T. AMAN AND BORO RICE TO RESIDUE RETENTION UNDER STRIP TILLAGE M. M. Hossain1*, M. Begum1, M.M. Rahman1 and A. Hashem2 1Department of Agronomy, Bangladesh Agricultural University 2Department of Agriculture and Food, Western Australia *Corresponding author and E-mail address: mmhshakil@yahoo.com Key words: Unpuddled transplanting, conventional tillage, strip tillage, residue retention Abstract An on-farm research was conducted at Gouripur upazila under Mymensingh district of Bangladesh during aman and boro season in 2013-14 to evaluate the performance of unpuddled rice cultivation. The rice var. Hybrid Krishan2 in aman and BRRI dhan28 in boro season were transplanted by two tillage practices viz., conventional tillage (CT) and strip tillage (ST) and two levels of crop residue i.e, no residue (R0) and 50% residue (R50). The experiment was designed in a randomized complete block design with four replications. ST yielded higher grains in aman season (5.67 t ha-1) and also in boro season (4.70 t ha-1) which were 9 and 13% higher compared to CT. Higher grain yield in ST leading to 26% higher BCR in aman and 23% higher in boro compared to CT. Retention of 50% residue increased by 5% yield in aman and by 4% yield in boro compared to no residue which contributed to 9% higher BCR in both aman and boro. ST combine with 50% residue retention yielded the highest grain yield in both of aman (5.97 t ha-1) and boro season (4.81t ha-1) which attributed to obtain the highest BCR in aman (3.08) and boro (2.78). Introduction Most of the farmers in the Asian continent cultivate rice (Oryza sativa L.) seedlings by transplanting in puddled soil for easy crop establishment (Singh et al., 2014). Lands are prepared by single or two passes in dry condition followed by exposure to sun for a couple of days. Then after inundation, final land is prepared by ploughing, cross ploughing and laddering in standing water. However, this traditional puddling method is labour, fuel, time and capital consuming (Islam et al., 2014). Nowadays most of tillage operations for puddling soil in Bangladesh are done by power tiller (Haque et al. 2008; Miah et al., 2002). Puddling is detrimental to soil physical conditions (Hobbs and Morris, 1996) through destroying soil aggregates, breaking capillary pores, and dispersing the soils (Gupta et al., 2003). Cloddy soil structure with less soil moisture and inadequate seed-soil contact resulted from the puddling (Sharma et al., 1995) makes land preparation difficult for the following winter crops (Islam et al. 2014). Puddled rice transplanting consumes about 20-40 % of total water required for raising crop (Singh et al., 2014) and it also promotes the formation of hard pan (Bhuiyan et al., 1995), reduces soil organic carbon at double rate, and decreases soil fertility (Grace, 2003), has losses of irrigation water (Sayre and Hobbs, 2003), and damages the ecological environment (Grace, 2003). Adoption of minimum tillage may be a very good alternative to puddled transplanting as it is using widely for many crops around the world (Singh et al., 2014). This technology has potentials to allow saving in labour, energy, water and time during rice establishment (Piggin et al., 2002). Compared to conventional tillage, 25-26% water could be saved by strip tillage under unpuddled system (Islam et al., 2012). Crop residues of cultivated crops are a significant factor for crop production through their effects on soil physical, chemical and biological functions as well as water and soil quality and increase crop yield (Kumar and Goh, 2000). Residue practice maintains soil micro-organisms and microbial activity which can also lead to weed suppression by the biological agents leading to increase crop yield (Kennedy, 1999). Considerable research work has been done on puddle transplanting, but there is alimited information on unpuddled rice transplanting under Bangladesh 40 Hossain et al. condition. Therefore, the present study was conducted to examine the performance of rice to unpuddled transplanting system with the retention of crop residues. Materials and Methods The experiment was conducted at farmer’s field of Durbacahra, Guipure, Mymensingh, Bangladesh (the latitude of 24.750 N and the longitude of 90.500 E) during aman (July-Mid November) and boro (Mid November-June) season in 2013-14. This experimental area belongs to the Old Brahmaputra Floodplain which is characterized by dark grey non calcareous alluvium soils and these soils are mostly sandy loam under Sonatala series (Brammer, 1996). Climatic (rainfall and thermal condition) data were collected from the nearest weather station and are presented in Figure 1. 0 50 100 150 200 250 300 350 400 0 5 10 15 20 25 30 35 40 R a in fa ll ,m m T em p er a tu re ,0c Month Rainfa ll Max temp Min temp Fig.1. Monthly temperature and rainfall distribution pattern in Gouripur during the cropping season of 2013-14 [Source: Department of Irrigation and Water Management, Faculty of Agricultural Engineering and Technology, Bangladesh Agricultural University, Mymensingh] The treatments were: (i) ipuddled condition conventional tillage (CT) and (ii) unpuddled condition strip tillage (ST) and two levels of crop residue viz., no residue (R0) and 50% residue (R50). The treatments were laid out in randomized complete block design with four replications using unit plots of 9 m × 5 m. In tillage practice, CT consisted of two passes primary tillage by two wheeler tractor (2 WT) and exposed to sun for two days followed by inundating whole plot and puddling by 2WT with two passes to complete land preparation. ST was done by Versatile Strip Tillage Planter (VSTP) in single pass operation before inundating the field. Three days before ST, pre-plant Glyphosate (Roundup) was applied @ 75 ml / 10 L water. After ST, the land was inundated with 3-5 cm standing water one day before transplanting operation for making the land soft enough to transplant seedlings (Islam et al., 2014). Twenty-five days old seedlings of rice var. Hybrid Krishan2 for aman season, and 40 days old seedlings of BRRI dhan28 for boro season were transplanted. Fertilizers were applied according to the recommendation of BRRI (2014). A spacing of 25 cm × 15 cm was maintained for both CT and ST with 2 or 3 seedlings hill-1. The crops were harvested at maturity from 3m × 3m each and then data were recorded. Grain yields were adjusted to 14% moisture content. Data were subjected to ANOVA using MSTAT-C and means separated by Duncan's Multiple Range Test. Results and discussions Effect of tillage practice on yield contributing characters and yield of rice 41 Response of T. Aman and Boro Rice to Residue Retention Under Strip Tillage Yield contributing characters of rice were significantly affected due to different tillage practice except the plant height, panicle length, and thousand grain weight (Table 1). The highest numbers of effective tillesr m-2 and numbers of fertile grains panicle-1, and the lowest numbers of non-effective tillesr m-2 and numbers of sterile grains panicle-1 were recorded from the ST compared to CT which attributed to higher yield (9% higher in aman and 13% higher in boro) for ST (Table 1). On the other hand, unpuddled rice transplanting by following ST produced higher BCR (around 25% in aman and 23% higher in boro compared to CT (Table 1). Table 1. Effect of tillage practice on yield contributing characters and yield of rice Tillage practice Plant height (cm) Effective tillers m-2 (no) Non effective tillers m-2 (no) Panicle length (cm) Fertile grains panicle-1 (no) Sterile grains panicle-1 (no) 1000- grain weight (gm) Grain yield (t ha-1) Benefit Cost Ratio Aman season CT 110.42 209b 71a 24 139b 47a 30 5.18a 1.76b ST 109.99 261a 44b 25 157a 29b 31 5.67b 2.21a LSD (0.05) NS 1.37 12.41 NS 5.48 2.55 0.41 0.22 0.13 CV (%) 2.74 12.67 11.71 2.40 3.47 2.27 1.32 0.34 4.72 Boro season CT 107.32 361b 77a 23.92 111b 35a 21.91 4.17b 2.16b ST 105.60 382a 47b 24.39 132a 16b 23.00 4.70a 2.67a LSD (0.05) NS 4.60 3.00 NS 8.29 2.90 NS 0.09 0.03 CV (%) 4.60 1.20 5.68 3.84 5.14 8.88 6.83 2.10 1.24 In a column, figure with similar letter do not differ significantly whereas dissimilar letter differ significantly. CT= Conventional tillage, ST= Strip tillage, Effect of residue retention on yield contributing characters and yield of rice Retention of 50% residue improved the numbers of effective tiller m-2 and the numbers of fertile grain panicle-1 while declined the numbers of non-effective tiller m-2 and the numbers of sterile grain panicle-1, compared to no residue in both aman and boro season (Table 2). Higher residue level yielded around 5% higher grains of Hybrid Krishan2 and 4% higher grains of BRRI dhan28 rice which attributed to earned 9% higher BCR in both aman and boro season (Table 2). Table 2. Effect residue level on yield contributing characters and yield of rice Residue level Plant height (cm) Effective tillers m-2 (no) Non effective tillers m-2 (no) Panicle length (cm) Fertile grains panicle-1 (no) Sterile grains panicle-1 (no) 1000 grain weight (gm) Grain yield (t ha-1) Benefit Cost Ratio Aman season R0 110.60 236b 53 24.59 148b 33a 31.70b 5.50b 2.61b R50 109.52 265a 40 24.51 157a 29b 32.06a 5.76a 2.86a LSD (0.05) NS 0.79 NS 0.31 3.16 1.47 0.23 0.13 0.75 CV (%) 2.74 12.67 11.71 2.40 3.47 2.27 1.32 0.34 4.72 42 Hossain et al. Boro season R0 104.90 373b 58b 24.39 100a 22a 22.71 4.52b 2.48b R50 106.37 385a 46a 24.25 121e 17b 22.93 4.70a 2.69a LSD (0.05) NS 2.65 1.73 NS 4.78 1.67 NS 0.05 0.018 CV (%) 4.60 1.20 5.68 3.84 5.14 8.88 6.83 2.10 1.24 In a column, figure with similar letter do not differ significantly whereas dissimilar letter differ significantly. R0= No residue, R50= 50% residue, Combination effect of tillage practice and residue level on yield contributing characters and yield of rice Combination between tillage practice and residue level exerted significant effect on all the plant characters except plant height, panicle length and weight of thousand grain in both aman and boro season (Table 3). ST retained 50% residue produced the highest number of effective tillers m-2, and number of fertile grains panicle-1, and the lowest numbers of non-effective tiller m-2 and number of sterile grains panicle-1 for both in aman and boro season. CT or ST with residue yielded the higher values of these parameters compared to no residues. ST with residue yielded the highest grain yield leading to the highest BCR while CT without residue yielded the lowest grain yield consequently the lowest BCR both in aman and boro season. Table 3. Combination effect of tillage practice and residue level on yield contributing characters and yield of rice Tillage practice Residue level Plant height (cm) Effective tillers m-2 (no) Non effective tillers m-2 (no) Panicle length (cm) Fertile grains panicle- 1 (no) Sterile grains panicle-1 (no) 1000 grain weight (gm) Grain yield (t ha-1) Benefit Cost Ratio Aman season R0 109.30 207cd 78d 24.20 119d 53a 28.50 5.17cd 1.63cCT R50 111.55 211 c 63c 24.60 140c 43b 31.28 5.20c 1.76c R0 110.87 241b 49b 24.67 154b 29c 30.84 5.57b 2.76bST R50 109.12 280a 35a 24.50 160a 26c 31.37 5.97a 3.08a LSD (0.05) NS 1.95 10.88 NS 5.76 3.60 NS 0.32 0.18 CV (%) 2.74 12.67 11.71 2.40 3.47 2.27 1.32 0.34 4.72 Boro season R0 108.35 359 84a 24.35 100c 41a 21.60 4.12d 2.08dCT R50 106.30 363 70b 24.50 121b 30b 22.23 4.24c 2.24c R0 104.21 376 53c 24.40 129ab 18c 22.93 4.60b 2.56bST R50 106.38 388 41d 24.20 139a 15c 23.07 4.81a 2.78a LSD (0.05) NS 6.50 4.25 NS 11.72 4.11 NS 0.13 0.045 CV (%) 4.60 1.20 5.68 3.84 5.14 8.88 6.83 2.10 1.24 In a column, figure with similar letter do not differ significantly whereas dissimilar letter differs significantly. CT= Conventional tillage, ST= Strip tillage, R0= No residue, R50= 50% residue The higher rice yields in ST obtained in this study are in the conformity with results of Mahajan et al. (2002) and Heatherly et al. (1994) Residue converts to mineralized nutrients which causes sufficient crop growth and facilitates higher yield over no residue (Shrivastav, 2014 and Dahal, 2014). Straw for controlling weeds in different crops have been suggested by Devasinghe et al. (2011). Residues prevents weed growth and supplies organic matter for heterotrophic N fixing microorganisms, which could be utilized by succeeding crops consequently results the higher yield (Mendoza and Samson, 1999; Patnaik, 1978). Conclusion 43 Response of T. Aman and Boro Rice to Residue Retention Under Strip Tillage Considering the rice grain yield and BCR, it may be concluded that, unpuddled rice transplantation may be a good alternative to existing conventional practice. 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