Method for improving yellow and brown soil in mining area by straw returning to field

Abstract

The invention discloses a method for improving yellow and brown soil in a mining area by straw returning, which comprises the following steps: taking back crop straws in a yellow and brown soil farmland in the mining area, and soaking the crop straws in a 1-3% hydrogen peroxide solution for 20-24 hours; then carrying out drying treatment; crushing in a crusher to obtain crop straws of which the length is less than or equal to 1 cm; uniformly mixing the crushed crop straws with a straw decomposing inoculant according to a ratio of 1 kg: 25 g; the straw decomposing inoculant is bacillus subtilis, and the effective viable count is 5.0-6.0 billion / g; the mixed crop straw is returned to the depth of 10-30 cm and mixed with the yellow brown soil layer with the depth of 10-30 cm, and it is ensured that the overall texture is uniform. According to the method, the straw is returned to the field in situ, operation is easy, the improvement speed is high, cost input is low, chemical additives do not need to be introduced in the treatment process, no extra pollution is generated, the acidity problem of the 20 cm soil layer is solved, the pore volume of the 30 cm soil layer is increased by 70%, and the method is especially suitable for planting of deep-rooted crops.

Description

Technical Field

[0001] The invention belongs to the technical field of improving the quality of cultivated land in mining areas, and specifically relates to a method for returning straw to fields to improve yellow-brown soil in mining areas. Background Art

[0002] The Huaihe River Basin is an important coal and grain production base in my country. According to statistics, the Huaihe River Basin has 13.762 billion tons of coal reserves. At the same time, the Huaihe River Basin carries 11% of the arable land and produces 16.7% of the country's grain. While coal mining in the Huaihe River Basin ensures energy security and promotes national economic development, it also brings about a series of problems such as soil quality decline, leading to an intensification of coal-grain conflicts. How to repair the damaged arable land in the mining area of ​​the Huaihe River Basin and alleviate the coal-grain conflict is one of the major problems currently faced.

[0003] The mining areas in Lianghuai (Huainan and Huaibei) are typical coal-grain complex areas in the Huaihe River Basin. As an obstacle in the area, the yellow-brown soil is heavy and nutrient-poor, resulting in low and unstable crop yields. As a typical agricultural solid waste in the Lianghuai mining area, straw is used to return to the fields to promote the resource utilization of agricultural solid waste. At the same time, in order to promote the comprehensive utilization of straw and improve soil quality, my country has implemented a series of straw management policies to encourage straw return to the fields. Therefore, returning straw to the fields to improve the yellow-brown soil in the mining area fully utilizes local advantages and saves application costs. It is a practice that adapts to local conditions. Domestic and foreign studies have shown that returning straw to the fields can have a positive impact on the development of soil pores, the stability of soil structure, and the improvement of soil compaction; it can provide macronutrients (N, P, K, Ca, Mg, etc.) and trace nutrients (S, Cu, B, Zn, Mo, etc.) required for crop growth; in terms of carbon sequestration, returning straw to the fields may be the most effective, economically feasible, and most potential method in my country.

[0004] Although the existing technology discloses soil improvement technologies such as the input of exogenous organic matter (biochar, cow dung, etc.) and inorganic matter (lime, fly ash, etc.), and the reduction of chemical fertilizers and the application of organic fertilizers, the above technologies still have problems such as complex operation and high cost. Therefore, it is very necessary to develop a method for improving the pore structure, fertility and carbon pool quality of yellow-brown soil in mining areas based on returning straw to the field. Summary of the invention

[0005] In order to solve at least one of the above problems, the present invention provides a method for returning straw to fields to improve yellow-brown soil in mining areas.

[0006] In order to achieve the above object, the present invention adopts the following technical means: A first aspect of the present invention provides a method for returning straw to fields to improve yellow-brown soil in mining areas, comprising the following steps: S1. Collect crop straw from the yellow-brown soil farmland in the mining area and dry it; S2, placing the dried crop straw in a crusher for crushing to obtain wheat straw with a length of ≤1 cm; S3, uniformly mixing the crushed crop straw with the straw decomposing bacteria agent in a ratio of 1 kg:25 g; the straw decomposing bacteria agent is Bacillus subtilis, and the effective live bacteria count is 500-600 million / g; S4. Return the mixed crop straw to the field to a depth of 10-30 cm, and mix it with the yellow-brown soil layer at a depth of 10-30 cm to ensure that the overall texture is uniform; the amount of crop straw returned to the field is based on the actual cultivated land area, and 2250-6750 kg is directly returned per square hectare of cultivated land.

[0007] S5. After returning the land to the field, add water to the land and maintain the relative moisture content at 70-80%; S6. Greenhouse cultivation.

[0008] In some embodiments of the present invention, preferably, the amount of crop straw returned to the field is based on the actual cultivated land area, with 6750 kg directly returned per square hectare of cultivated land.

[0009] In some embodiments of the present invention, the crop straw is immersed in a 1%-3% hydrogen peroxide solution for 20-24 hours before drying.

[0010] In some embodiments of the present invention, the crop straw includes, but is not limited to, wheat straw, corn straw, soybean straw, peanut straw, and may also be other crop straws that are adaptably planted on the yellow-brown soil in mining areas.

[0011] In some embodiments of the present invention, after returning the crops to the field, they are cultured in a greenhouse for 30-50 days.

[0012] Beneficial Effects of the Invention Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a scheme for treating recycled straw with safe microbial agents and returning the straw directly to the field in situ. The method is not only simple in operation steps, convenient in improvement, fast in speed and low in cost, but also does not require the introduction of chemical additives during the treatment process, and no additional pollution is generated. In addition, the acidity problem of the 20 cm soil layer of the soil decomposed with the microbial agent is improved, making it more suitable for crop planting.

[0013] This method can be used to soak the straw in hydrogen peroxide solution first, and the free radicals accelerate the oxidation and decomposition of the straw. After mixing with Bacillus subtilis, it can be directly returned to the field to different soil depths of 10 / 20 / 30 cm, which can achieve three-dimensional improvement of the soil. When 6750 kg of straw is directly returned to the field per square hectare of cultivated land, different soil depths of 10 / 20 / 30 cm can achieve good return to the field effect. Such a large amount of return to the field can meet the processing needs of straw in the mining area, and maximize the return of all straw to the field. After returning to the field, it can adapt to the needs of different cultivated layers of yellow-brown soil in the mining area, especially the increase in pore volume of the 30 cm soil layer is 70%, which is particularly suitable for deep-rooted crops. At the same time, the amount of straw returned to the field can be flexibly selected according to the degree of soil degradation in the mining area, taking into account both economy and effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The comprehensive soil fertility index of the 10 cm soil layer after treatment with different bacterial agent ratios is shown; Figure 2 The comprehensive soil fertility index of different soil layers after returning 10 cm straw to the field is shown; Figure 3 The soil carbon pool management index of different soil layers after returning 10 cm straw to the field is shown; Figure 4 The comprehensive soil fertility index of different soil layers after returning 20 cm straw to the field is shown; Figure 5 The soil carbon pool management index of different soil layers after returning 20 cm straw to the field is shown; Figure 6 The schematic diagram of soil pore network model for different soil layers is shown; Figure 7 The comprehensive soil fertility index of different soil layers after returning 30 cm straw to the field is shown; Figure 8 The soil carbon pool management index of different soil layers after returning 30 cm straw to the field is shown; Fig. 9 The comprehensive soil fertility index of different soil layers treated with different bacterial agents is shown. DETAILED DESCRIPTION

[0015] The following examples are used to demonstrate preferred embodiments of the present invention. It will be appreciated by those skilled in the art that the techniques disclosed in the following examples represent techniques discovered by the inventors that can be used to implement the present invention and therefore can be considered as preferred embodiments of the present invention. However, it will be appreciated by those skilled in the art based on this specification that many modifications may be made to the specific embodiments disclosed herein and still achieve the same or similar results without departing from the spirit or scope of the present invention.

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs, and the materials cited herein and those cited by them are incorporated by reference. Those skilled in the art will recognize or will learn through routine experimentation that there are many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the claims.

[0017] The technical solution of the present application is further described in detail below in conjunction with specific implementation methods.

[0018] Example 1 (1) The wheat straw from the yellow-brown soil farmland in mining area A was retrieved and soaked in pure water for 24 h. After soaking, the wheat straw was washed with pure water and then soaked in 1% hydrogen peroxide solution for 20 h. (2) Place the soaked and cleaned wheat straw in an oven at 80°C for 48 hours for drying, and then pack and seal the dried wheat straw; (3) Place the dried wheat straw in a high-power crusher for crushing. The final length of the wheat straw should be ≤1 cm; (4) The crushed wheat straw was evenly mixed with the straw decomposing bacteria agent in the ratio of 1 kg:15 g, 1 kg:20 g, 1 kg:25 g, and 1 kg:30 g; wherein the straw decomposing bacteria agent was Bacillus subtilis, and the effective viable bacteria count was 500 million / g; (5) Then the wheat straw mixed with the composting agent was heated to 6750 kg / hm2. 2 Return the fertilizer to the field to a depth of 10 cm and mix it evenly with the yellow-brown soil in the 10 cm soil layer to ensure that the overall texture is uniform; and add water to maintain a relative moisture content of 80%.

[0019] Detection and analysis The 10 cm soil layer before returning to the field was used as the control group CK1, and the soil layers of each soil layer cultured at room temperature for 40 days were analyzed. Among them, the sample of the treatment group with a ratio of 1 kg:15 g of crushed wheat straw to straw composting agent was named MIR1; the sample of the treatment group with a ratio of 1 kg:20 g was named MIR2; the sample of the treatment group with a ratio of 1 kg:25 g was named MIR3; and the sample of the treatment group with a ratio of 1 kg:30 g was named MIR4.

[0020] The relative increases of soil carbon pool management index of MIR1, MIR2, MIR3, and MIR4 compared with CK1 were 96.34%, 107.12%, 120.04%, and 106.55%, respectively ( Figure 1 ). Among them, C1 is 6750 kg / hm 2The increase in the amount of wheat straw returned to the fields was the most obvious, which effectively improved the soil carbon pool quality in the 10 cm yellow-brown soil layer.

[0021] The above results show that at 6750 kg / hm 2 When the returning amount was 10 cm and the returning depth was 10 cm, the ratio of crushed wheat straw to straw composting agent was 1 kg:25 g, which significantly improved the soil carbon pool quality in the soil layer.

[0022] Example 2 (1) Wheat straw from the yellow-brown soil farmland in mining area A was collected and soaked in 1% hydrogen peroxide solution for 24 h; (2) Place the soaked and cleaned wheat straw in an oven at 80°C for 48 hours for drying, and then pack and seal the dried wheat straw; (3) Place the dried wheat straw in a high-power crusher for crushing. The final length of the wheat straw should be ≤1 cm; (4) Evenly mix the crushed wheat straw and the straw decomposing agent in a ratio of 1 kg:25 g; wherein the straw decomposing agent is Bacillus subtilis, and the effective viable count is 500 million / g; (5) Then the wheat straw mixed with the composting agent was heated at 2250 kg / hm2. 2 Return the fertilizer to the field to a depth of 10 cm and mix it evenly with the yellow-brown soil in the 10 cm soil layer to ensure that the overall texture is uniform; and add water to maintain a relative moisture content of 80%.

[0023] Example 3 (1) Wheat straw from the yellow-brown soil farmland in mining area A was collected and soaked in 1% hydrogen peroxide solution for 24 h; (2) Place the soaked and cleaned wheat straw in an oven at 80°C for 48 hours for drying, and then pack and seal the dried wheat straw; (3) Place the dried wheat straw in a high-power crusher for crushing. The final length of the wheat straw should be ≤1 cm; (4) The crushed wheat straw and the straw decomposing agent are uniformly mixed in a ratio of 1 kg:25 g, wherein the straw decomposing agent is Bacillus subtilis with an effective live bacterial count of 500 million / g; (5) Then the wheat straw mixed with the composting agent was heated at 4500 kg / hm2. 2 Return the fertilizer to the field to a depth of 10 cm and mix it evenly with the yellow-brown soil in the 10 cm soil layer to ensure that the overall texture is uniform; and add water to maintain a relative moisture content of 80%.

[0024] Example 4 (1) Wheat straw from the yellow-brown soil farmland in mining area A was collected and soaked in 1% hydrogen peroxide solution for 24 h; (2) Place the soaked and cleaned wheat straw in an oven at 80°C for 48 hours for drying, and then pack and seal the dried wheat straw; (3) Place the dried wheat straw in a high-power crusher for crushing. The final length of the wheat straw should be ≤1 cm; (4) Evenly mix the crushed wheat straw and the straw decomposing agent in a ratio of 1 kg:25 g; wherein the straw decomposing agent is Bacillus subtilis, and the effective viable count is 500 million / g; (5) Then the wheat straw mixed with the composting agent was heated to 6750 kg / hm2. 2 Return the fertilizer to the field to a depth of 10 cm and mix it evenly with the yellow-brown soil in the 10 cm soil layer to ensure that the overall texture is uniform; and add water to maintain a relative moisture content of 80%.

[0025] Detection and analysis The 10 cm soil layer before returning the straw to the field was taken as the control group CK1, and the soil layers of each soil layer after returning the 10 cm straw to the field in Examples 1 to 3 and incubating at room temperature for 40 days were analyzed, among which the sample of the treatment group of Example 1 was named A1; the sample of the treatment group of Example 2 was named B1; and the sample of the treatment group of Example 3 was named C1.

[0026] (1) The pore distribution characteristics obtained by pore analysis are shown in Table 1.

[0027] Table 1. Soil pore distribution characteristics of 10 cm returned soil layer

[0028] (2) The soil nutrient characteristics of the soil layer obtained by nutrient characteristic analysis are shown in Table 2.

[0029] Table 2 Soil nutrient characteristics of 10 cm returned soil layer

[0030] (3) Referring to the "National Second Soil Survey Nutrient Classification Standard", the comprehensive soil fertility was calculated using the Nemerow index method. The comprehensive fertility index of the soil layer obtained by comprehensive fertility analysis is shown in Table 3 and Figure 2 shown.

[0031] Table 3 Comprehensive fertility index of soil in the 10 cm returned soil layer

[0032] Note: The comprehensive soil fertility index is calculated based on the Nemerow index method, and the soil fertility levels are divided. Extremely low fertility: 0≤IFI<0.5; low fertility: 0.5≤IFI<1.0; medium fertility: 1.0≤IFI<1.5 (first-level medium fertility: 1.0≤IFI<1.125; second-level medium fertility: 1.125≤IFI<1.25; third-level medium fertility: 1.25≤IFI<1.375; fourth-level medium fertility: 1.375≤IFI<1.5); high fertility: 1.5≤IFI<2.0 (first-level high fertility: 1.5≤IFI<1.625; second-level high fertility: 1.625≤IFI<1.75; third-level high fertility: 1.75≤IFI<1.875; fourth-level high fertility: 1.875≤IFI<2.0); extremely high fertility: 2.0≤IFI≤3.0.

[0033] (4) The soil carbon pool management index obtained by carbon pool management analysis is shown in Table 4 and Figure 3 shown.

[0034] Table 4 Soil carbon pool management index of 10 cm returned soil layer

[0035] From the comparative analysis of the above results, it can be seen that the volume proportion of pores <300 μm in A1, B1, and C1 decreased by 8.28%, 10.23%, and 20.26% respectively compared with CK1, while the volume proportion of pores >300 μm increased by 268.59%, 276.22%, and 375.34% respectively compared with CK1. 2 The increase in the amount of wheat straw returned to the field was the most obvious, which effectively improved the soil pore structure of the 10 cm yellow-brown soil layer, transforming its pores from relatively small pores to relatively large pores.

[0036] The specific performance of soil comprehensive fertility is as follows: the relative increase of soil comprehensive fertility of A1, B1, and C1 compared with CK1 is 6.64%, 10.63%, and 12.17% respectively. The relative increase of pH value of A1, B1, and C1 compared with CK1 is 1.08%, 1.97%, and 4.85% respectively. Among them, C1 is 6750 kg / hm 2 The increase in the amount of wheat straw returned to the fields was the most obvious, which effectively improved the comprehensive soil fertility of the 10 cm yellow-brown soil layer and effectively alleviated the acidification of the 10 cm tillage layer of the yellow-brown soil, making it more suitable for crop planting.

[0037] The relative increases of soil carbon pool management index of A1, B1 and C1 were 46.63%, 75.18% and 120.04% respectively compared with CK1. 2The increase in the amount of wheat straw returned to the fields was the most obvious, which effectively improved the soil carbon pool quality in the 10 cm yellow-brown soil layer.

[0038] The above results show that the method of this application is 6750 kg / hm 2 The amount of returning fertilizer to the field and the depth of returning fertilizer to the field of 10 cm significantly improved the porosity of the soil, the comprehensive fertility of the soil and the quality of the soil carbon pool.

[0039] Example 5 (1) Wheat straw from the yellow-brown soil farmland in mining area A was collected and soaked in 1% hydrogen peroxide solution for 22 h; (2) Place the soaked and cleaned wheat straw in an oven at 60°C for 48 hours for drying, and then pack and seal the dried wheat straw; (3) Place the dried wheat straw in a high-power crusher for crushing. The final length of the wheat straw should be ≤1 cm; (4) Evenly mix the crushed wheat straw and the straw decomposing agent in a ratio of 1 kg:25 g; wherein the straw decomposing agent is Bacillus subtilis, and the effective viable count is 500 million / g; (5) Then the wheat straw mixed with the composting agent was heated at 2250 kg / hm2. 2 Return the fertilizer to the field to a depth of 20 cm and mix it evenly with the yellow-brown soil in the 20 cm soil layer to ensure that the overall texture is uniform; and add water to maintain a relative moisture content of 80%.

[0040] Example 6 (1) Wheat straw was collected from the yellow-brown soil farmland in the mining area and soaked in 1% hydrogen peroxide solution for 22 h; (2) Place the soaked and cleaned wheat straw in an oven at 60°C for 48 hours for drying, and then pack and seal the dried wheat straw; (3) Place the dried wheat straw in a high-power crusher for crushing. The final length of the wheat straw should be ≤1 cm; (4) Evenly mix the crushed wheat straw and the straw decomposing agent in a ratio of 1 kg:25 g; wherein the straw decomposing agent is Bacillus subtilis, and the effective viable count is 500 million / g; (5) Then the wheat straw mixed with the composting agent was heated at 4500 kg / hm2. 2 Return the fertilizer to the field to a depth of 20 cm and mix it evenly with the yellow-brown soil in the 20 cm soil layer to ensure that the overall texture is uniform; and add water to maintain a relative moisture content of 80%.

[0041] Example 7 (1) Wheat straw was collected from the yellow-brown soil farmland in mining area A and soaked in 1% hydrogen peroxide solution for 22 h; (2) Place the soaked and cleaned wheat straw in an oven at 60°C for 48 hours for drying, and then pack and seal the dried wheat straw; (3) Place the dried wheat straw in a high-power crusher for crushing. The final length of the wheat straw should be ≤1 cm; (4) Evenly mix the crushed wheat straw and the straw decomposing agent in a ratio of 1 kg:25 g; wherein the straw decomposing agent is Bacillus subtilis, and the effective viable count is 500 million / g; (5) Then the wheat straw mixed with the composting agent was heated to 6750 kg / hm2. 2 Return the fertilizer to the field to a depth of 20 cm and mix it evenly with the yellow-brown soil in the 20 cm soil layer to ensure that the overall texture is uniform; and add water to maintain a relative moisture content of 80%.

[0042] Detection and analysis The 0-10 cm and 10-20 cm soil layers before returning to the field were used as the control groups, named CK1 and CK2, respectively; In the treatment group of Example 4, the sample cultured at room temperature for 40 days was named A2; the corresponding 0-10 cm soil layer was named A2-1, and the 10-20 cm soil layer was named A2-2; In the treatment group of Example 5, the sample cultured at room temperature for 40 days was named B2; the corresponding 0-10 cm soil layer was named B2-1, and the 10-20 cm soil layer was named B2-2; In the treatment group of Example 6, the sample cultured at room temperature for 40 days was named C2; the corresponding 0-10 cm soil layer was named C2-1, and the 10-20 cm soil layer was named C2-2.

[0043] (1) The pore distribution characteristics obtained by pore analysis are shown in Table 5.

[0044] Table 5 Distribution characteristics of soil pores in the 20 cm returned soil layer

[0045] (2) The soil nutrient characteristics of the soil layer obtained by nutrient characteristic analysis are shown in Table 6.

[0046] Table 6 Soil nutrient characteristics of different soil layers after returning to the field at 20 cm

[0047] (3) Referring to the "National Second Soil Survey Nutrient Classification Standard", the comprehensive soil fertility was calculated using the Nemerow index method. The comprehensive fertility index of the soil layer obtained by comprehensive fertility analysis is shown in Table 7 and Figure 4 shown.

[0048] Table 7 Comprehensive fertility index of soil in the 200 cm returned soil layer

[0049] (4) The soil carbon pool management index obtained by carbon pool management analysis is shown in Table 8 and Figure 5 shown.

[0050] Table 8 Soil carbon pool management index of 20 cm returned soil layer

[0051] From the comparative analysis of the above results, it can be seen that the volume proportion of pores <300 μm in A2-1, B2-1, and C2-1 decreased by 31.29%, 34.28%, and 35.07% respectively compared with CK1, while the volume proportion of pores >300 μm increased by 360.08%, 394.62%, and 403.63% respectively compared with CK1; the volume proportion of pores <300 μm in A2-2, B2-2, and C2-2 decreased by 7.09%, 15.42%, and 22.53% respectively compared with CK2, while the volume proportion of pores >300 μm increased by 54.38%, 118.39%, and 172.94% respectively compared with CK2. Among them, C2-1 and C2-2, i.e. 6750 kg / hm 2 The increase in the amount of wheat straw returned to the field was the most obvious, which effectively improved the soil pore structure of each layer of 20 cm yellow-brown soil, transforming its pores from relatively small pores to relatively large pores.

[0052] The specific performance of soil comprehensive fertility is as follows: the relative increase of soil comprehensive fertility of A2-1, B2-1, and C2-1 compared with CK1 is 2.73%, 6.87%, and 9.52%, respectively; the relative increase of soil comprehensive fertility of A2-2, B2-2, and C2-2 compared with CK2 is 5.99%, 8.31%, and 11.10%, respectively. The relative increase of pH value of 2-1, B2-1, and C2-1 compared with CK1 is 0.36%, 1.62%, and 2.87%, respectively; the relative increase of pH value of A2-2, B2-2, and C2-2 compared with CK2 is 0.17%, 0.52%, and 0.69%, respectively. Among them, C2-1 and C2-2 are 6750 kg / hm 2 The increase in the amount of wheat straw returned to the fields was the most obvious, which effectively improved the comprehensive soil fertility of each layer of 20 cm yellow-brown soil and effectively alleviated the acidification of the 20 cm tillage layer of yellow-brown soil, making it more suitable for crop planting.

[0053] The relative increases of soil carbon pool management index of A2-1, B2-1 and C2-1 were 4.30%, 14.52% and 64.64% respectively compared with CK1; the relative increases of soil carbon pool management index of A2-2, B2-2 and C2-2 were 27.55%, 36.52% and 69.62% respectively compared with CK2. 2 The increase in the amount of wheat straw returned to the fields was the most obvious, which effectively improved the soil carbon pool quality in each layer of 20 cm yellow-brown soil.

[0054] Example 8 (1) Wheat straw was collected from the yellow-brown soil farmland in the mining area and soaked in 1% hydrogen peroxide solution for 20 h; (2) Place the soaked and cleaned wheat straw in an oven at 70°C for 48 hours for drying, and then pack and seal the dried wheat straw; (3) Place the dried wheat straw in a high-power crusher for crushing. The final length of the wheat straw should be ≤1 cm; (4) Evenly mix the crushed wheat straw and the straw decomposing agent in a ratio of 1 kg:25 g; wherein the straw decomposing agent is Bacillus subtilis, and the effective viable count is 500 million / g; (5) Then the wheat straw mixed with the composting agent was heated at 2250 kg / hm2. 2 Return the fertilizer to the field to a depth of 30 cm and mix it evenly with the yellow-brown soil in the 30 cm soil layer to ensure that the overall texture is uniform; and add water to maintain a relative moisture content of 80%.

[0055] Example 9 (1) Wheat straw was collected from the yellow-brown soil farmland in mining area A and soaked in 1% hydrogen peroxide solution for 20 h; (2) Place the soaked and cleaned wheat straw in an oven at 70°C for 48 hours for drying, and then pack and seal the dried wheat straw; (3) Place the dried wheat straw in a high-power crusher for crushing. The final length of the wheat straw should be ≤1 cm; (4) Evenly mix the crushed wheat straw and the straw decomposing agent in a ratio of 1 kg:25 g; wherein the straw decomposing agent is Bacillus subtilis, and the effective viable count is 500 million / g; (5) Then the wheat straw mixed with the composting agent was heated at 4500 kg / hm2. 2 Return the fertilizer to the field to a depth of 30 cm and mix it evenly with the yellow-brown soil in the 30 cm soil layer to ensure that the overall texture is uniform; and add water to maintain a relative moisture content of 80%.

[0056] Example 10 (1) Wheat straw was collected from the yellow-brown soil farmland in mining area A and soaked in 1% hydrogen peroxide solution for 20 h; (2) Place the soaked and cleaned wheat straw in an oven at 70°C for 48 hours for drying, and then pack and seal the dried wheat straw; (3) Place the dried wheat straw in a high-power crusher for crushing. The final length of the wheat straw should be ≤1 cm; (4) Evenly mix the crushed wheat straw and the straw decomposing agent in a ratio of 1 kg:25 g; wherein the straw decomposing agent is Bacillus subtilis, and the effective viable count is 500 million / g; (5) Then the wheat straw mixed with the composting agent was heated to 6750 kg / hm2. 2 Return the replacement amount to the field to a depth of 30 cm and mix it with the yellow-brown soil in the 30 cm soil layer to ensure that the overall texture is uniform; and add water to maintain a relative moisture content of 80%.

[0057] Detection and analysis The soils in the 0-10 cm, 10-20 cm, and 20-30 cm layers before returning to the field were used as control groups and named CK1, CK2, and CK3, respectively; In the treatment group of Example 7, the sample cultured at room temperature for 40 days was named A3; the corresponding 0-10 cm soil layer was named A3-1, the 10-20 cm soil layer was named A3-2; ​​and the 20-30 cm soil layer was named A3-3; In the treatment group of Example 8, the sample cultured at room temperature for 40 days was named B3; the corresponding 0-10 cm soil layer was named B3-1, the 10-20 cm soil layer was named B3-2; and the 20-30 cm soil layer was named B3-3; In the treatment group of Example 9, the sample cultured at room temperature for 40 days was named C3; the corresponding 0-10 cm soil layer was named C3-1, the 10-20 cm soil layer was named C3-2, and the 20-30 cm soil layer was named C3-3.

[0058] (1) The pore distribution characteristics obtained by pore analysis are shown in Table 9. Schematic diagram of soil pore network model for different soil layers is shown in Figure 6 shown.

[0059] Table 9 Distribution characteristics of soil pores in the 30 cm returned soil layer

[0060] (2) The soil nutrient characteristics of the soil layer obtained by nutrient characteristic analysis are shown in Table 10.

[0061] Table 1030 cm soil nutrient characteristics of different soil layers after returning to the field

[0062] (3) Referring to the "National Second Soil Survey Nutrient Classification Standard", the comprehensive soil fertility was calculated using the Nemerow index method. The comprehensive fertility index of the soil layer obtained by comprehensive fertility analysis is shown in Table 11 and Figure 7 shown.

[0063] Table 1130 cm soil comprehensive fertility index of returned soil layer

[0064] (4) The soil carbon pool management index obtained by carbon pool management analysis is shown in Table 12 and Figure 8 shown.

[0065] Table 1 Soil carbon pool management index of 230 cm returned soil layer

[0066] Note: The above carbon pool management index is based on CK1, CK2, and CK3 as reference standards and is set at 100; if it is greater than 100, it is considered that the carbon pool quality is improved, and the larger the index, the better the carbon pool quality.

[0067] The comparison and analysis of the above results show that the volume proportion of pores <300 μm in A3-1, B3-1, and C3-1 is reduced by 29.44%, 34.023%, and 34.83% respectively compared with CK1, while the volume proportion of pores >300 μm is increased by 338.92%, 391.74%, and 401.13% respectively compared with CK1; the volume proportion of pores <300 μm in A3-2, B3-2, and C3-2 is reduced by 6.95%, 18.06%, and 24.46% respectively compared with CK2, while the volume proportion of pores >300 μm is increased by 53.25%, 138.59%, and 187.68% respectively compared with CK2; the volume proportion of pores <300 μm in A3-3, B3-3, and C3-3 is reduced by 5.24%, 10.46%, and 10.80% respectively compared with CK3, while the volume proportion of pores >300 μm is increased by 14.8% and 20.9% respectively. The volume proportion of μm pores increased by 43.74%, 65.51% and 70.47% respectively compared with CK3. Among them, C3-1, C3-2 and C3-3 are 6750 kg / hm 2 The increase in the amount of wheat straw returned to the field was the most obvious, which effectively improved the soil pore structure of each layer of 30 cm yellow-brown soil, transforming its pores from relatively small pores to relatively large pores.

[0068] The specific performance of soil comprehensive fertility is as follows: the relative increase of soil comprehensive fertility of A3-1, B3-1, and C3-1 compared with CK1 is 2.83%, 4.55%, and 5.91% respectively; the relative increase of soil comprehensive fertility of A3-2, B3-2, and C3-2 compared with CK2 is 1.77%, 7.05%, and 10.57% respectively; the relative increase of soil comprehensive fertility of A3-3, B3-3, and C3-3 compared with CK3 is 7.99%, 12.53%, and 16.21% respectively. The relative increase of pH value of A3-1, B3-1, and C3-1 compared with CK1 is 4.13%, 4.85%, and 5.21% respectively; the relative increase of pH value of A3-2, B3-2, and C3-2 compared with CK2 is 3.12%, 3.12%, and 3.81% respectively. Among them, C3-1, C3-2, and C3-3 are 6750 kg / hm 2 The increase in the amount of wheat straw returned to the fields was the most obvious, which effectively improved the comprehensive soil fertility of each layer of 30 cm yellow-brown soil and effectively alleviated the acidification of the 20 cm tillage layer of yellow-brown soil, making it more suitable for crop planting.

[0069] The relative increases of soil carbon pool management index of A3-1, B3-1 and C3-1 were 0.28%, 9.80% and 57.0% respectively compared with CK1; the relative increases of soil carbon pool management index of A3-2, B3-2 and C3-2 were 27.87%, 30.63% and 46.83% respectively compared with CK2; the relative increases of soil carbon pool management index of A3-3, B3-3 and C3-3 were 29.44%, 43.77% and 58.11% respectively compared with CK2. Among them, C3-1, C3-2 and C3-3 are 6750 kg / hm 2 The increase in the amount of wheat straw returned to the fields was the most obvious, which effectively improved the soil carbon pool quality in each layer of 30cm yellow-brown soil.

[0070] Embodiment 11 (1) Wheat straw was collected from the yellow-brown soil farmland in mining area B and soaked in 3% hydrogen peroxide solution for 22 h; (2) Place the soaked and cleaned wheat straw in an oven at 80°C for 48 hours for drying, and then pack and seal the dried wheat straw; (3) Place the dried wheat straw in a high-power crusher for crushing. The final length of the wheat straw should be ≤1 cm; (4) The crushed wheat straw and the straw decomposing agent were uniformly mixed in a ratio of 1 kg:25 g; in the first group, the straw decomposing agent was Bacillus subtilis, with an effective live bacteria count of 500 million / g; in the second group, the straw decomposing agent was a mixed agent of Bacillus subtilis (50%) and Phanerochaete chrysosporium (50%), with an effective live bacteria count of 500 million / g; in the third group, the straw decomposing agent was Phanerochaete chrysosporium, with an effective live bacteria count of 500 million / g; (5) Then the wheat straw mixed with the composting agent was heated to 6750 kg / hm2. 2 Return the fertilizer to the field to a depth of 20 cm and mix it evenly with the yellow-brown soil in the 20 cm soil layer to ensure that the overall texture is uniform; and add water to maintain a relative moisture content of 80%.

[0071] Detection and analysis The 0-20 cm soil layer before returning to the field was used as the control group, and the samples were named CK; the first treatment group, the samples cultured at room temperature for 40 days were named MA1; the second treatment group, the samples cultured at room temperature for 40 days were named MA2; the third treatment group, the samples cultured at room temperature for 40 days were named MA3.

[0072] The pore distribution characteristics of the soil layer obtained by pore analysis are shown in Table 9; referring to the "National Second Soil Census Nutrient Classification Standard", the comprehensive soil fertility was calculated by the Nemerow index method, and the comprehensive fertility analysis was performed. The comprehensive fertility index is shown in Table 13 and Fig. 9 shown.

[0073] Table 1320 cm soil comprehensive fertility index

[0074] From the analysis of the results of Example 11, it can be seen that the relative increase in the comprehensive soil fertility of MA1 compared with CK is 11.32%; the relative increase in the comprehensive soil fertility of MA2 compared with CK is 6.92%; the relative increase in the comprehensive soil fertility of MA3 compared with CK is 3.14%. In general, the relative increase effect of the comprehensive soil fertility of MA1 is about 1.6 times that of MA2, and the relative increase effect of the comprehensive soil fertility of MA1 is about 3.6 times that of MA3, indicating that compared with the use of Phanerochaete chrysosporium alone and the use of a mixed bacterial agent of 50% Bacillus subtilis and 50% Phanerochaete chrysosporium, the use of Bacillus subtilis alone more effectively improves the comprehensive fertility of yellow-brown soil.

[0075] Bacillus subtilis was used to decompose wheat straw, and the amount of wheat straw returned to the field was selected to be 2250 / 4500 / 6750kg / hm 2 The depth of returning wheat straw to the field is 10 / 20 / 30 cm. According to Example 2-11, the amount of wheat straw returned to the field is 6750 kg / hm2 When the soil pore structure, soil fertility and soil carbon pool quality of 10 cm soil layer, 20 cm soil layer (0-10 cm, 10-20 cm), 30 cm soil layer (0-10 cm, 10-20 cm, 20-30 cm) were effectively improved. Compared with 2250 / 4500 kg / hm 2 The amount of soil returned to the field is 6750 kg / hm 2 The most significant effect was achieved when the amount of wheat straw returned to the field was 6750 kg / hm 2 When combined with the bacterial agent Bacillus subtilis, it can meet the different depth scenarios of returning straw to the field in yellow-brown soil, and achieve rapid improvement of the pore structure, fertility, and carbon pool quality of yellow-brown soil. In addition, this method is low-cost, simple, and effective, so it is an ideal method for improving yellow-brown soil farmland.

[0076] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as references separately. In addition, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined in the present application.

Claims

1. A method for returning straw to fields to improve yellow-brown soil in mining areas, characterized in that: The steps include: S1. Collect crop straw from the yellow-brown soil farmland in the mining area and dry it; S2, placing the dried crop straw in a crusher for crushing to obtain crop straw with a length of ≤1 cm; S3, uniformly mixing the crushed crop straw with the straw decomposing bacteria agent in a ratio of 1 kg:25 g; the straw decomposing bacteria agent is Bacillus subtilis, and the effective live bacteria count is 500-600 million / g; S4. Return the mixed crop straw to the field to a depth of 10-30 cm, and mix it with the yellow-brown soil layer at a depth of 10-30 cm to ensure that the overall texture is uniform; the amount of crop straw returned to the field is based on the actual cultivated land area, and 2250-6750 kg is directly returned per square hectare of cultivated land. S5. After returning the land to the field, add water to the land and maintain the relative moisture content at 70-80%; S6. Greenhouse cultivation.

2. The method for returning straw to fields to improve yellow-brown soil in mining areas according to claim 1, characterized in that: The amount of crop straw returned to the field in step S4 is based on the actual cultivated land area, with 6750 kg of crop straw directly returned per square hectare of cultivated land.

3. The method for returning straw to fields to improve yellow-brown soil in mining areas according to claim 1, characterized in that: The crop straw is immersed in a 1%-3% hydrogen peroxide solution for 20-24 hours before drying.

4. The method for returning straw to fields to improve yellow-brown soil in mining areas according to claim 1, characterized in that: The crop straws are wheat straws, corn straws, soybean straws and peanut straws.

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