Academic Journal of Science and Technology ISSN: 2771-3032 | Vol. 13, No. 1, 2024 215 Feasibility Study of Mud Shale as a Soil Organic Reconstructing Material and Soil Improvement Material Liheng Xia1, 2, 3, Panpan Zhang1, 2, 3, Jing Zhang1, 2, 3 1Shaanxi Provincial Land Engineering Construction Group Co., Ltd, Xi'an 710075, China 2Institute of Land Engineering & Technology, Shaanxi Provincial Land Engineering Construction Group Co., Ltd, Xi'an 710075, China 3Key Laboratory of Cultivated Land Quality Monitoring and Conservation, Ministry of Agriculture and Rural Affairs, Xi'an 710075, China Abstract: In this study, on the basis of the physical and chemical properties of mud shale, after preliminary analysis, it is believed that it has a certain improvement effect on the soil types of new arable land with different textures. Therefore, it is proposed to set up a test on the compounding of mud shale weathered material with ancient soil (clay soil) and loamy soil (loamy soil) to explore its influence on improving the structure and nutritional characteristics of new arable land, in order to explore the technical measures for upgrading the land remediation quality and improve the economic, social and ecological benefits of land remediation projects. In order to explore the technical measures to improve the quality of land remediation and enhance the economic, social and ecological benefits of land remediation projects. Keywords: Muddy shale; Soil organic remodeling; Soil improvement; Materials; Physical and chemical properties. 1. Introduction Land consolidation projects are an important means and effective measures for increasing arable land. These projects have been implemented for many years, resulting in a considerable amount of new arable land. However, the quality of this new land is not optimistic. This is because the new arable land mainly comes from wastelands, abandoned industrial and mining lands, saline-alkali lands, stony lands, and other lands that are difficult to utilize or have poor planting effects. The soil quality after reclamation is poor, mainly manifested in poor soil texture and structure, poor aeration, water retention, and fertility retention capabilities[1]. On the other hand, the soil nutrient content of the new arable land is extremely low, lacking in organic matter and trace elements, which cannot meet the normal growth needs of crops. In Shaanxi Province, the soil of new arable land can be roughly divided into three types according to texture: clayey soil, loamy soil, and sandy soil. These soils are either structurally poor or have poor nutritional status from the beginning[2]. The newly reclaimed land is even more characterized by barren soil and poor planting effects. If the physical and chemical properties of these barren soils are not improved, the purpose of land consolidation cannot be achieved, nor can the national requirement of "insisting on the balance of arable land occupation and compensation, increasing the quantity of arable land, and improving the quality of arable land" be met. More importantly, it cannot fundamentally solve the sustainable use of arable land resources. Faced with such a situation, under the premise of reasonable economic conditions, seeking appropriate external additives to improve the physical and chemical properties of the soil is an effective way to improve the efficiency of water and fertilizer use, enhance the quality of land consolidation, and increase the productivity of new arable land[3]. Currently, there are many studies on the improvement of soil quality by soil amendments for new arable land at home and abroad. According to the source of raw materials[4-10], soil amendments can be divided into natural amendments, synthetic amendments, natural-synthetic copolymer amendments, and biological amendments. Natural amendments are relatively low-cost and easy to obtain, mainly divided into inorganic materials and organic materials. Studies on the impact of inorganic materials on soil quality mainly focus on materials such as zeolite, bentonite, fly ash, gypsum, and vermiculite. Zeolite has good water retention capacity. After being applied to the soil, it can increase the water content of the cultivated layer by 1% to 2%, and increase the field water holding capacity of the cultivated layer in arid areas by 5% to 15%. Moreover, its strong adsorption capacity and high cation exchange capacity can adsorb heavy metals in the soil and promote the release of nutrients in the soil, which has a certain effect on improving the current situation of water and fertilizer deficiency in new arable land soil. Using bentonite to improve sandy soil can increase the content of clay particles, increase soil water content, and the bentonite has certain swelling properties, dispersibility, and adhesion, which can increase the number of aggregates, increase soil porosity, and reduce soil bulk density when applied to the soil. Fly ash, as an inorganic solid waste, is also commonly used to improve the physical properties of clay and sandy soils, and can also increase the content of boron, zinc, silicon, etc., in the soil. Although these natural minerals have certain effects on improving soil structure and soil chemical properties, most of the related studies are focused on a single type of soil, and are more inclined to the improvement of sandy soils, and rarely consider the impact characteristics on different texture types of soil. In practical application, there are still some theoretical and technical issues, such as the amount of application, the method of application, and the limitation of the reserves of these natural minerals on their large-scale promotion and application. Therefore, exploring universally applicable materials with relatively abundant reserves, and studying their impact on the quality of new arable land soil of different texture types, is of great significance for further improving the quality of new arable land and promoting the ecological 216 construction of land consolidation projects[11]. In the implementation process of the "Yao Qu Town Land Consolidation Project" in Tongchuan City, Shaanxi Province, it was found that the Weibei soil and stone mixed mountain area contains a large amount of mud shale weathering products. Laboratory testing has shown that mud shale contains minerals such as montmorillonite, which has the characteristics of bentonite, and at the same time contains relatively rich mineral elements. It is considered to mix it into new arable land, which can improve the soil structure to a certain extent and increase the nutrients in the soil. At present, the research on mud shale is mainly focused on engineering aspects such as bearing capacity, solubility, and disintegration characteristics, and there are few reports on its use as a soil amendment for new arable land. Based on the physical and chemical properties of mud shale, this study preliminarily believes that it has a certain improvement effect on different texture types of new arable land soil. Therefore, it is planned to set up a compounding experiment of mud shale weathering products with ancient soil (clay soil) and loess (loamy soil) to explore its impact on improving the structure and nutritional characteristics of new arable land soil, in order to explore technical measures to improve the quality of land consolidation, and to improve the economic, social, and ecological benefits of land consolidation projects. 2. Materials and Methods 2.1. Overview of the study area The "Yao Qu Land Consolidation Project" is located in Yao Qu Town, Yaozhou District, Tongchuan City, and belongs to the "terrace transformation" and "dry land to irrigated land" project types implemented on loess and stone hills. The project area is a mixed mountainous area of mud shale weathering, with originally extremely shallow soil layers, belonging to wasteland grasslands. The Tongchuan branch of the group has implemented "terrace transformation" topographic reshaping projects, "soil body reshaping" projects mainly involving soil covering, "dry to water" water conservancy projects that bring water from the Ju River to the hills, and "rapid maturation of raw soil with biological techniques" such as planting black beans on newly formed land. The project area contains a large amount of mud shale, and the soil layer is generally thin, often requiring soil adjustment to ensure soil layer thickness. Through on-site surveys, the soil sources covered here are mainly divided into two types. One is the surface yellow soil with good texture, suitable for agricultural planting. The other is the ancient yellow soil accumulated in a flat terrain on the hillside, which has relatively heavy soil texture and is relatively deficient in medium and large element nutrients. The soil is prone to waterlogging and has poor water permeability during the rainy season. Coupled with the presence of a large amount of mud shale in the area, the land after rectification is mainly a mixed structure of mudstone weathering products and soil. 2.2. Field Soil Sampling The sampling area is located in the land consolidation project area of Yao Qu Town, Tongchuan City. Four types of soil with different soil structures in the gentle slope area of the project area were selected: undisturbed soil without mud shale weathering products (WT), cultivated land without mud shale weathering products (NT), undisturbed soil with mud shale weathering products (YWT), and cultivated land with mud shale weathering products after land consolidation (YRT). For each type of soil, five sampling points were selected using the "S" method, and the sampling depth was 0- 20 cm based on the actual situation. The soil sample measurement indicators include: bulk density, mechanical composition, organic matter, aggregates, and soil water content. At the same time, soil samples were collected before the project area was consolidated, and mixed samples of mud shale weathering products and soil in the newly added arable land area were collected after the consolidation. The sampling depth was 0-20 cm and 20-40 cm. After the sample collection, the physical and chemical properties were analyzed to study the impact of mud shale weathering products on the physical and chemical properties of the soil in the newly added arable land area. 2.3. Indoor Pot Experiment Based on the characteristics of shale, mixed proportions of shale weathering products with different types of soil are selected to set up pot experiments, as shown in Table 1 and Figure 3. By adding shale to local loess and ancient soil in different proportions, the impact on soil stability and soil physical and chemical properties is analyzed. The crops chosen for planting are alfalfa, ryegrass, and other grass crops as indicative crops. After the pot experiment is set up, soil samples are collected under each treatment at the end of the ryegrass growing season for basic physical and chemical property analysis. Table 1. Pot Experiment Treatments Analysis of major research institutions Treatment VN：VH Treatment VN：VH H1 1:1 G1 1:1 H2 1:2 G2 1:2 H3 1:5 G3 1:5 CK1 0:1 CK2 0:1 3. Results and Discussion 3.1. The Impact of Mudstone Shale Weathering Products on Soil Structure Soil quality is the most sensitive indicator of dynamic changes in soil conditions; it reflects not only the changes in soil management but also the soil's ability to recover from degradation. Many natural and anthropogenic ecological processes, such as climate fluctuations, vegetation succession, and land use changes, significantly affect the spatiotemporal evolution of soil quality. The addition of mudstone during the project implementation will have a certain impact on the soil properties. The level of soil fertility depends on the soil nutrient status, which directly affects crop yields. Figure 4 reflects the levels of organic matter, calcium carbonate, clay content, and bulk density in the 0-20 cm soil layer under different treatment types. The content of soil organic matter is in the order of YWT>NT>YRT>WT, meaning that the undisturbed soil has the lowest organic matter content, and the soil containing mudstone weathering products has the highest organic matter content, which is 3.4 times that of the former. The organic matter content of the two types of farmland is close, but the 217 farmland without mudstone has a slightly higher organic matter content. The main reason is that the cultivation time of this type of farmland is long, and the accumulation of organic matter is higher. However, the organic matter of the farmland with mudstone is higher than that of the undisturbed soil, indicating that the incorporation of mudstone can increase the organic matter content to a certain extent. Clay and calcium carbonate are also important binding materials for soil structure. When the content of calcium carbonate in the soil increases, calcium carbonate aggregates with soil particles to form granular structure, reducing small pores and increasing large pores. This results in reduced water retention capacity and enhanced aeration capacity of the soil under the same suction. The content of calcium carbonate in calcic horizons is generally between 20% and 30%. Under each treatment type, the content of soil calcium carbonate does not differ much, all around 8%, while the farmland with mudstone weathering products after reclamation is slightly less than the other types. When the content of mudstone is large, the aeration condition of the soil should be paid attention to. From the perspective of clay content and soil bulk density, undisturbed soil has a relatively large clay content and bulk density, which are 18.93% and 1.46 g/cm³, respectively. In contrast, the farmland without mudstone weathering products has clay content and bulk density of 14.26% and 1.28 g/cm³, respectively. The farmland with mudstone weathering products after reclamation has 16.29% and 1.35 g/cm³, and the undisturbed soil with mudstone weathering products has 14.35% and 1.43 g/cm³. The above results reflect that mudstone weathering products have a certain impact on undisturbed soil and farmland. By comparing the undisturbed soil with the undisturbed soil containing mudstone, it is found that mudstone can increase the organic matter content of undisturbed soil to a certain extent. For the farmland after reclamation, the newly added arable land with mudstone has slightly higher clay content and greater bulk density, which can increase the soil's binding force to a certain extent. Figure 4. Physicochemical properties of soil under different treatment conditions Water-stable aggregates play a significant role in maintaining the stability of soil structure, making them crucial for assessing the stability of soil structure. The content of water-stable aggregates of different sizes in the soil can be obtained through the wet sieving method, as shown in Table 2. In the wet sieving method, there is a significant difference in the content of aggregates under various treatments. The content of aggregates larger than 0.25 mm in the soil layer is highest in the undisturbed soil containing mudstone shale (YWT), at 46.5%; followed by the arable land without mudstone shale weathering products (NT) and the arable land with mudstone shale weathering products after reclamation (YRT), with aggregate contents larger than 0.25 mm of 25.2% and 20.3%, respectively; the smallest is the undisturbed soil, with an aggregate content larger than 0.25 mm of 3.5%. Looking at the MWD, NT and YWT have higher values, indicating stronger water stability. This indicates that the original undisturbed soil containing mudstone shale has high stability, but the original undisturbed soil has poor water stability and is prone to water and soil erosion. In contrast, the water stability of farmland that has been cultivated for a long time and newly added arable land 218 containing mudstone weathering products is higher than that of undisturbed soil in the area. Table 2. Content of Aggregates of Different Sizes Under Different Treatments Treatment Content of Aggregates of Different Sizes (%) MWD (mm) ＞5mm 2-5mm 1-2mm 0.5-1mm 0.25-0.5mm ＜0.25mm ＞0.25mm WT 1.30 0.44 0.34 0.32 1.05 96.54 3.46 0.21 NT 22.99 1.26 0.39 0.23 0.32 74.82 25.18 1.30 YWT 8.05 9.36 19.53 4.86 4.69 53.50 46.50 1.14 YRT 3.79 2.62 6.60 3.50 3.78 79.71 20.29 0.52 3.2. The Impact of Mudstone Shale Weathering Products on Soil Moisture Content Figure 5 reflects the average soil moisture content under different treatment conditions, and Table 3 is the analysis of differences. It can be seen that with in the soil layer depths of 0-10 cm and 10-20 cm, the soil moisture content is WT