A method for constructing a sponge plough layer based on the cooperative application of organic manure and straw and application thereof

Abstract

The application provides a sponge plough layer construction method based on organic manure and straw cooperative field returning and application thereof, and relates to the technical field of soil improvement and crop planting.The application provides a sponge plough layer construction method based on organic manure and straw cooperative field returning, which comprises the following steps: S1: spreading wheat straw on the soil to be improved, then spraying a composite straw decomposing agent on the wheat straw, and applying organic manure in the soil after 3-5 months and rotary ploughing; S2: repeating step S1 after rotary ploughing for 7-9 months; S3: spreading wheat straw on the soil after rotary ploughing for 7-9 months, then spraying a composite straw decomposing agent on the wheat straw, and deep ploughing after 3-5 months of application of organic manure in the soil to be improved.The construction method can not only improve the soil organic matter content and reduce the soil bulk density, but also improve the soil water holding capacity and water conductivity rate, and improve the soil fertility and crop yield.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement and crop planting technology, specifically involving a method for constructing a sponge topsoil layer based on the synergistic return of organic manure and straw to the field and its application. Background Technology

[0002] Winter wheat-summer maize rotation is the main planting pattern in the major grain-producing areas of North my country. However, long-term high-intensity continuous cropping and the use of single chemical fertilizers have led to a continuous degradation of soil health, specifically manifested in: accelerated consumption of soil organic matter, compaction of the topsoil structure, decreased soil buffering capacity, and a significant weakening of basic soil fertility.

[0003] In recent years, climate change has further exacerbated these problems. Frequent and persistent heavy rainfall in autumn has hindered corn harvesting and delayed wheat sowing, disrupting traditional agricultural schedules. Meanwhile, although heat resources are showing an increasing trend, the frequent occurrence of extreme weather events such as seasonal high temperatures, droughts, and cold waves creates multiple environmental stresses on crops during their critical growth stages. Against this backdrop, shortcomings such as insufficient soil fertility, slow improvement in organic matter, and declining buffering capacity have been significantly amplified, highlighting the increasing vulnerability of traditional production methods. The existing topsoil structure is unable to efficiently retain rainfall during the flood season or provide stable water supply during droughts, severely restricting the stability and security of grain production capacity.

[0004] Existing technologies mostly focus on single measures (such as direct straw return to the field, one-time application of organic fertilizer, or spraying of biological agents), lacking a systematic coupled design of "material type—application timing—tillage depth—soil structure response." This results in slow organic matter improvement, delayed improvement of topsoil structure, and difficulty in synergistically leveraging water storage and conduction functions. Especially in major grain-producing areas where extreme rainfall and seasonal droughts alternate, it is difficult to form a stable and sustainable sponge effect. Therefore, there is an urgent need to provide a method for constructing a healthy topsoil that can solve the above problems, in order to achieve the synergistic goals of water storage and moisture conservation, drought and flood resistance, and continuous improvement of soil fertility. Summary of the Invention

[0005] To address the aforementioned technical problems, the primary objective of this invention is to provide a method for constructing a sponge topsoil layer based on the synergistic return of organic manure and straw to the field. This method utilizes a compound straw-decomposing microbial agent to drive rapid straw conversion, humic acid-optimized organic manure for targeted replenishment, and a phased tillage approach of "two rotations and one deep tillage." This achieves the synergistic application of straw and organic fertilizer in time and space within the crop rotation cycle, not only increasing soil organic matter content and reducing soil bulk density, but also improving soil water holding capacity and water conduction rate, thereby enhancing soil fertility and crop yield.

[0006] A second objective of this invention is to provide the application of the above-described construction method in increasing soil organic matter content and / or reducing soil bulk density.

[0007] A third objective of this invention is to provide the application of the above-described construction method in improving soil water holding capacity and / or improving soil water conductivity.

[0008] A fourth objective of this invention is to provide the application of the above-described construction method in reducing fertilizer application and / or reducing irrigation water consumption.

[0009] The fifth objective of this invention is to provide the application of the above-described construction method in increasing wheat or corn yield.

[0010] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: This invention provides a method for constructing a sponge topsoil layer based on the synergistic return of organic manure and straw to the field, comprising the following steps: S1: Spread wheat straw on the soil to be improved, then spray compound straw decomposing bacteria on the wheat straw, and apply organic manure to the soil and rotary tillage 3-5 months later. S2: Repeat step S1 after 7-9 months of rotary tillage; S3: After rotary tillage for 7-9 months, spread wheat straw on the soil again, then spray compound straw decomposing bacteria on the wheat straw. After 3-5 months, apply organic manure to the soil and deep plow. The compound straw decomposing microbial agent comprises the following components by weight: 15-25 parts of Trichoderma harzianum, 10-20 parts of Aspergillus niger, 10-20 parts of Protozoa chrysospora, 2-4 parts of cellulase, and 1-3 parts of lignin peroxidase.

[0011] In one embodiment, the length of the wheat straw is ≤10 cm; the spraying rate of the compound straw decomposing agent is 1~3 kg / mu; and the viable count of Trichoderma harzianum is 5×10⁻⁶. 8 ~2×10 9 CFU / g, the viable count of the Aspergillus niger is 3 × 10⁻⁶. 8 ~1×10 9 CFU / g, the viable count of *Phanerochaete chrysosporium* was 3 × 10⁻⁶. 8 ~1×10 9 The cellulase activity is 5000~30000 U / g, and the lignin peroxidase activity is 500~2000 U / g.

[0012] In one embodiment, the organic manure has an organic matter content of 30-40%, a seed germination index of 80-90%, a humic acid content of 20-25%, and a humic acid to fulvic acid mass ratio of 1-2:1.

[0013] In one implementation method, the amount of organic manure applied in S1 is the theoretical application rate F ± 10%, and the formula for calculating the theoretical application rate F is: F=[ΔSOM×H×BD×100] / (OM×η); Where ΔSOM is the difference in organic matter content of the topsoil before and after improvement; H is the target thickness of the topsoil; BD is the bulk density of the soil to be improved; OM is the organic matter content of organic manure; and η is the efficiency coefficient. The amount of organic manure applied in S2 is 0.7 to 0.9 times that in S1; the amount of organic manure applied in S3 is 1.0 to 1.2 times that in S1.

[0014] In one implementation, the value of ΔSOM ranges from 1 to 15 g / kg; the value of H ranges from 30 to 35 cm; and the value of BD ranges from 1.1 to 1.6 g / cm. 3 The value of OM ranges from 30% to 50%, and the value of η ranges from 0.3% to 0.5%.

[0015] In one implementation, the depth of rotary tillage is 12-18 cm; the depth of deep plowing is 30-35 cm.

[0016] The present invention also provides the application of the above-described construction method in improving soil water holding capacity and / or improving soil water conduction rate.

[0017] The present invention also provides the application of the above-described construction method in increasing soil organic matter content and / or reducing soil bulk density.

[0018] The present invention also provides the application of the above-described construction method in reducing fertilizer application and / or reducing irrigation water consumption.

[0019] The present invention also provides the application of the above-described construction method in increasing wheat or corn yield.

[0020] The advantages of this invention compared to existing technologies are as follows: This invention provides a method for constructing a sponge topsoil layer based on the synergistic return of organic manure and straw to the field. The invention uses functionalized microbial agents as the starting engine for wheat straw and organic manure with optimized humic acid components as the structural framework. Through a two-rotation, one-deep tillage method, the spatiotemporal synergistic application of wheat straw and organic manure is achieved, enabling precise coupling within the crop rotation cycle. This allows the materials to exert their effects at the optimal time and space. A three-year crop rotation cycle can construct a sponge topsoil structure with both high water holding capacity and high water conductivity. This not only improves soil fertility but also reduces fertilizer application and irrigation water consumption, saving costs. Furthermore, it can increase wheat or corn yields, achieving stability and security in grain production capacity. Detailed Implementation

[0021] In this invention, the sponge topsoil refers to loose and porous soil with good structure, strong soil fertility, excellent water absorption, water storage, water retention and fertilizer retention capacity, which can effectively improve the soil's drought resistance, flood resistance and nutrient utilization efficiency. The effective thickness of the topsoil is usually more than 30 cm.

[0022] This invention provides a method for constructing a sponge topsoil layer based on the synergistic return of organic manure and straw to the field, comprising the following steps: S1: Spread wheat straw on the soil to be improved, then spray compound straw decomposing bacteria on the wheat straw, and apply organic manure to the soil and rotary tillage 3-5 months later. S2: Repeat step S1 after 7-9 months of rotary tillage; S3: After rotary tillage for 7-9 months, wheat straw is spread on the soil again, and then a compound straw decomposing agent is sprayed on the wheat straw. After 3-5 months, organic manure is applied to the soil and deep tillage is carried out. After steps S1, S2 and S3, the present invention constructs the soil to be improved into a sponge tillage layer with high water holding capacity, high water conductivity, and high soil fertility.

[0023] This invention selects soil to be improved and tests its basic properties, including soil type, soil bulk density, and soil organic matter content. The soil to be improved has an organic matter content <15 g / kg and a soil bulk density >1.4 g / cm³. 3 .

[0024] In this invention, wheat straw is spread on the soil to be improved. The length of the wheat straw is ≤10 cm, and the spreading rate is 300-500 kg / mu. As an optional implementation, this invention uses a cutting and pulverizing device to complete the cutting, pulverizing, and spreading during winter wheat harvesting, ensuring that the length of the pulverized wheat straw is ≤10 cm, the stubble height is ≤8 cm, and the unevenness rate of spreading is ≤15%. This invention also adds a rear-mounted straw pulverizing and spreading device to the grain outlet of a wheat combine harvester, pulverizing and spreading the wheat straw simultaneously with wheat harvesting.

[0025] After scattering wheat straw, a compound straw decomposing microbial agent is sprayed onto the wheat straw. During spraying, the compound straw decomposing microbial agent is mixed with water at a mass-to-volume ratio of 1:45~55 g / mL, and then evenly sprayed onto the surface of the wheat straw. The preferred mass-to-volume ratio is 1:50 g / mL. The spraying amount of the compound straw decomposing microbial agent is 1~3 kg / mu (approximately 0.067 hectares), preferably 2 kg / mu (approximately 0.067 hectares).

[0026] By weight, the compound straw decomposing microbial agent comprises the following components: 15-25 parts of Trichoderma harzianum, 10-20 parts of Aspergillus niger, 10-20 parts of Phanerochaete chrysosporium, 2-4 parts of cellulase, and 1-3 parts of lignin peroxidase; preferably, the compound straw decomposing microbial agent comprises the following components: 20 parts of Trichoderma harzianum, 15 parts of Aspergillus niger, 15 parts of Phanerochaete chrysosporium, 3 parts of cellulase, and 2 parts of lignin peroxidase.

[0027] In this invention, *Trichoderma harzianum* is activated and cultured on PDA medium for 4-6 days at a temperature of 26-30°C. The viable count of *Trichoderma harzianum* after activation is 5 × 10⁻⁶. 8 ~2×10 9 CFU / g, preferably 1×10⁻⁶ viable cells of *Trichoderma harzianum*. 9 CFU / g or 1.5×10 9 CFU / g. *Aspergillus niger* was activated and cultured on Czapek's medium for 3-5 days at a temperature of 28-32℃. The viable count of *Aspergillus niger* after activation culture was 3 × 10⁻⁶. 8 ~1×10 9 CFU / g, preferably 5 × 10⁻⁶ viable bacteria of Aspergillus niger. 8 CFU / g, 7×10 8 CFU / g or 9×10 8 CFU / g. *Phanerochaete chrysosporium* was activated and cultured on PDA medium for 6-8 days at a temperature of 26-30℃. The viable count of *Phanerochaete chrysosporium* after activation was 3 × 10⁻⁶. 8 ~1×10 9 CFU / g, preferably 5 × 10⁻⁶ viable bacteria of *Phanerochaete chrysosporium*. 8 CFU / g, 7×10 8 CFU / g or 9×10 8 CFU / g. In this invention, *Trichoderma harzianum*, *Procambarus chrysospora*, and *Aspergillus niger* are derived from commercially available products.

[0028] The cellulase described in this invention has an enzyme activity of 5000~30000 U / g, preferably 10000 U / g, 15000 U / g, 20000 U / g, or 25000 U / g; the lignin peroxidase has an enzyme activity of 500~2000 U / g, preferably 1000 U / g or 1500 U / g. In this invention, the cellulase and lignin peroxidase are derived from commercially available products.

[0029] In this invention, the preparation method of the compound straw decomposing microbial agent includes the following steps: mixing each strain and enzyme according to the above weight ratio, adding 4-6% skim milk powder, and freeze-drying to obtain the compound straw decomposing microbial agent. The freeze-drying temperature is -40~-50℃, preferably -55℃, and the freeze-drying time is 24~48 h, preferably 36 h. The effective viable bacteria count in the compound straw decomposing microbial agent of this invention is 3×10⁻⁶. 8 ~5×10 9 CFU / g. In this invention, the mass ratio of the skim milk powder is preferably 5%.

[0030] Three to five months after spraying the compound straw decomposing microbial agent, organic manure is applied to the soil and rotary tilled to a depth of 12 to 18 cm, preferably 14 cm or 16 cm. As an optional implementation, after harvesting corn, the corn stalks are removed from the field, and then organic manure is applied to the soil.

[0031] In this invention, the organic manure contains 30-40% organic matter, has a seed germination index of 80-90%, a humic acid content of 20-25%, and a humic acid to fulvic acid mass ratio of 1-2:1. The preparation method of the organic manure according to this invention includes the following steps: mixing pig manure and wheat straw at a weight ratio of (1-2):1, fermenting for 25-30 days to obtain organic manure, wherein the fermentation temperature is 40-65℃. In this invention, pig manure and wheat straw are mixed at a weight ratio of (1-2):1, preferably 1.5:1; after mixing, the initial moisture content is adjusted to 60-70%, piled up, covered with film, and fermented for 25-30 days, preferably 28 days; the fermentation is aerobic fermentation, wherein the aerobic fermentation method involves laying anti-clogging aeration pipes at the bottom, and the fermentation temperature is 40-65℃, preferably 45℃, 50℃, or 60℃.

[0032] In this invention, the amount of organic manure applied in S1 is the theoretical application rate F ± 10%, and the formula for calculating the theoretical application rate F is as follows: F=[ΔSOM×H×BD×100] / (OM×η); Wherein, ΔSOM is the difference in organic matter content of the topsoil before and after improvement, ranging from 1 to 15 g / kg; H is the target thickness of the topsoil, ranging from 30 to 35 cm; and BD is the bulk density of the soil to be improved, ranging from 1.1 to 1.6 g / cm³. 3OM represents the organic matter content of organic manure, ranging from 30% to 50%; η represents the efficiency coefficient, ranging from 0.3 to 0.5. In this invention, the difference in organic matter content in the topsoil before and after improvement is the difference between the target organic matter content of the improved soil and the organic matter content of the soil before improvement. The target organic matter content of the improved soil is 15-30 g / kg. This invention uses rotary tillage to mix wheat straw and organic manure into the upper part of the topsoil, stimulating shallow layer activity. After rotary tillage, the soil is leveled and compacted, completing the first round of processing.

[0033] Seven to nine months after completing the first round of processes, step S1 is repeated for the second round. The second round of processes involves spreading wheat straw on the rotary-tilled soil, then spraying a compound straw-decomposing microbial agent onto the wheat straw. Three to five months later, organic manure is applied to the soil, followed by rotary tillage. The operation steps for the second round are the same as the first round and will not be repeated here. In this invention, the amount of organic manure applied in S2 is 0.7 to 0.9 times that in S1. In the second round, the amount of organic manure applied is 0.7 to 0.9 times that in the first round. Rotary tillage mixes the newly applied organic manure and wheat straw with the accumulated soil organic carbon from the previous round into the upper and middle layers of the topsoil, promoting the formation of water-stable large aggregates in the middle soil layer and the stable accumulation of organic matter. Without affecting the construction speed of the sponge topsoil layer, the amount of organic manure applied is appropriately reduced, thereby reducing the cost of soil improvement.

[0034] Seven to nine months after completing the second round of tillage, the third round of tillage is carried out. The third round of tillage involves spreading wheat straw on the soil after the second round of rotary tillage, then spraying a compound straw decomposing agent on the wheat straw. Three to five months later, organic manure is applied to the soil, followed by deep plowing. The steps for spreading wheat straw and spraying the compound straw decomposing agent and organic manure are the same as in the first round of tillage and will not be repeated here. This invention uses a moldboard plow for deep plowing, with a depth of 30 to 35 cm, preferably 32 cm or 34 cm. In this invention, the amount of organic manure applied in step S3 is 1.0 to 1.2 times that in step S1. In the third round of tillage, the amount of organic manure applied is 1.0 to 1.2 times that in the first round. By increasing the amount of organic manure applied and combining it with deep plowing, organic matter is introduced into the deeper tillage layer, breaking up the plow pan and constructing a sponge-like structure that runs vertically through the soil, significantly improving the organic matter content and water conductivity of the deeper soil layers. This invention first uses rotary tillage to mix wheat straw and organic manure from the first two rounds into the upper and middle layers of the tillage layer. Then, a third round of deep plowing breaks up the plow pan. Using a two-rotary-one-deep tillage method, the accumulated organic matter and organic manure from the upper and middle layers are mixed into the deeper layers, achieving a spatial and temporal synergistic embedding of wheat straw and organic manure. This constructs interconnected water-conducting channels, reconstructing the overall tillage layer, improving soil fertility, and creating a sponge tillage layer with a depth of over 30 cm. This method can form a sponge tillage layer in 3 years, increasing soil organic matter content by 23.2%; reducing soil bulk density by 9.1%; increasing soil saturated hydraulic conductivity (Ksat) by 87.5%; increasing soil field water holding capacity by 20.0%; and increasing the number of water-stable large aggregates (>0.25 mm) in the soil by 84.9%, thus improving the stability of the sponge tillage layer. Under a rainfall of 100 mm / h (simulated rainstorm intensity), the surface runoff initiation time of the sponge tillage layer is 45 minutes, and the total surface runoff is 12.5 m³. 3 / acre, the time required for saturated water to drain from the sponge topsoil layer (0-30 cm) to field capacity (from saturation) was reduced to 6.2 hours, significantly reducing the risk of waterlogging. Furthermore, under 15 days of continuous drought, the soil moisture content in the sponge topsoil layer (0-40 cm) was 18.5%, the leaf water potential was -0.85 MPa, and the stomatal conductance was 0.21 mol·m⁻². -2 ·s -1 This significantly reduces drought stress on crops. During crop cultivation, fertilizer application is reduced by 20% and irrigation water consumption by 18% compared to conventional methods, while simultaneously increasing crop yield by 7.5%.

[0035] Based on the construction method of the present invention, the water holding capacity and soil hydraulic conductivity of the soil to be improved can be increased. The present invention also provides the application of the above-mentioned construction method in improving soil water holding capacity and / or improving soil hydraulic conductivity.

[0036] Based on the construction method of the present invention, it is possible to increase the organic matter content in the soil and reduce the soil bulk density. The present invention also provides the application of the above-mentioned construction method in increasing the organic matter content of soil and / or reducing the soil bulk density.

[0037] Based on the fact that the construction method of the present invention can reduce the amount of fertilizer applied and irrigation water used, the present invention also provides the application of the above-mentioned construction method in reducing the amount of fertilizer applied and / or reducing the amount of irrigation water used.

[0038] Based on the fact that the construction method of the present invention can increase the yield of wheat and corn, the present invention also provides the application of the above-mentioned construction method in increasing the yield of wheat or corn.

[0039] In this invention, liquid functional fertilizer is applied once each during the seedling and jointing stages of wheat / corn. The application rate during the seedling stage is 10-15 L / mu (approximately 0.067 hectares); during the jointing stage, the application rate is 18-25 L / mu (approximately 0.067 hectares). The liquid functional fertilizer comprises *Trichoderma harzianum* spores and potassium humate, with the concentration of the *Trichoderma harzianum* spores being 4 × 10⁻⁶. 7 ~6×10 7 CFU / mL, the preferred concentration being 5 × 10⁻⁶. 7 CFU / mL; the concentration of potassium humate is 6~10 g / L, preferably 8 g / L.

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the embodiments, but these should not be construed as limiting the scope of protection of this invention.

[0041] Unless otherwise specified, the materials, reagents, etc. used in the following examples are commercially available. Unless otherwise specified, they are generally used under conventional conditions or under conditions recommended by the company.

[0042] Trichoderma harzianum (CGMCC No. 41155), Aspergillus niger (CGMCC No. 6316), and Protozoa chrysophagus (CGMCC No. 5.776) were obtained from the China General Microbiological Culture Collection Center.

[0043] Example 1 A method for constructing a sponge topsoil layer based on the synergistic return of organic manure and straw to the field: Compound straw decomposing microbial agent: Trichoderma harzianum CGMCC No. 41155 (1×10⁻⁶) 9 20 samples of CFU / g, and Aspergillus niger CGMCC NO. 6316 (8×10) 815 samples of *Phanerochaete chrysosporium* CGMCC No. 5.776 (1×10⁻⁶ CFU / g) were tested. 9 15 portions of CFU / g, 3 portions of cellulase (enzyme activity of 20000 U / g), and 2 portions of lignin peroxidase (enzyme activity of 1500 U / g).

[0044] Organic manure: organic matter content is 35.2%, seed germination index is 85%, humic acid content is 22.6%, total nutrients are 5.1%, moisture content is 28.5%, and the mass ratio of humic acid to fulvic acid is 1.45:1.

[0045] S1: Spread 8 cm long wheat straw at 400 kg / mu on the soil to be improved, then spray compound straw decomposition bacteria evenly on the wheat straw at a rate of 2 kg / mu. After 4 months, apply organic manure to the soil at a rate of 13.30 tons / hectare, and then till the soil to a depth of 15 cm to mix it evenly, and then level and compact it. The theoretical application rate of organic manure is F = [ΔSOM × H × BD × 100] / (OM × η), where ΔSOM is 3.8 g / kg, H is 32 cm, and BD is 1.54 g / cm. 3 OM is 35.2% and η is 0.4.

[0046] S2: After 8 months of rotary tillage, repeat step S1, with an application rate of 10.64 tons / hectare of organic manure. S3: After 8 months of rotary tillage, spread wheat straw on the soil according to step S1, spray compound straw decomposing bacteria on the wheat straw, and apply organic manure 4 months later. The amount of organic manure applied is 14.63 tons / hectare. Then, use a moldboard plow to deeply plow the soil to a depth of 32 cm to mix it evenly, and then level and compact it.

[0047] Example 2 A method for constructing a sponge topsoil layer based on the synergistic return of organic manure and straw to the field: Compound straw decomposing microbial agent: Trichoderma harzianum CGMCC No. 41155 (1×10⁻⁶) 9 24 samples of CFU / g and Aspergillus niger CGMCC NO. 6316 (9×10) 8 18 samples of *Phanerochaete chrysosporium* (CFU / g) and *Phanerochaete chrysosporium* CGMCC No. 5.776 (9×10⁻⁶ CFU / g) were tested. 8 20 portions of CFU / g, 2 portions of cellulase (enzyme activity of 15000 U / g), and 3 portions of lignin peroxidase (enzyme activity of 2000 U / g).

[0048] Organic manure: organic matter content is 38.5%, seed germination index is 87%, humic acid content is 23.4%, total nutrients are 4.6%, moisture content is 26.9%, and the mass ratio of humic acid to fulvic acid is 1.50:1.

[0049] S1: Spread 6 cm long wheat straw at 400 kg / mu on the soil to be improved, then spray compound straw decomposition bacteria evenly on the wheat straw at a rate of 2 kg / mu. Four months later, apply organic manure to the soil to be improved at a rate of 15.6 tons / hectare, and then till the soil to a depth of 16 cm to mix it evenly, and then level and compact it. The theoretical application rate of organic manure is F = [ΔSOM × H × BD × 100] / (OM × η), where ΔSOM is 4.4 g / kg, H is 35 cm, and BD is 1.56 g / cm³. 3 OM is 38.5% and η is 0.4.

[0050] S2: After 8 months of rotary tillage, repeat step S1, with an application rate of 12.48 tons / hectare of organic manure. S3: After 8 months of rotary tillage, spread wheat straw on the soil according to step S1, spray compound straw decomposing bacteria on the wheat straw, and apply organic manure 4 months later. The amount of organic manure applied is 17.16 tons / hectare. Then, use a moldboard plow to deeply plow the soil to a depth of 35 cm to mix it evenly, and then level and compact it.

[0051] Example 3 A method for constructing a sponge topsoil layer based on the synergistic return of organic manure and straw to the field: Preparation method of compound straw decomposing microbial agent: Take Trichoderma harzianum CGMCC No. 41155 and activate it in PDA medium at 28℃ for 5 days until the viable count of Trichoderma harzianum is 1×10⁻⁶. 9 CFU / g. Aspergillus niger (CGMCC NO. 6316) was taken and activated on Czapek's medium at 30℃ for 4 days until the viable count of Aspergillus niger was 8 × 10⁻⁶. 8 CFU / g. *Phanerochaete chrysosporium* (CGMCC No. 5.776) was collected and activated in PDA medium at 28°C for 7 days until the viable count of *Phanerochaete chrysosporium* reached 1×10⁻⁶. 9 CFU / g. Take 20 parts of *Trichoderma harzianum* CGMCC No. 41155, 15 parts of *Aspergillus niger* CGMCC No. 6316, 15 parts of *Phanerochaete chrysosporium* CGMCC No. 5776, 3 parts of cellulase (enzyme activity 20000 U / g), and 2 parts of lignin peroxidase (enzyme activity 1500 U / g), mix well, add 5% skim milk powder, and freeze-dry at -45℃ for 36 hours to obtain an effective viable count of 3.5 × 10⁻⁶.9 A compound straw decomposing microbial agent with CFU / g.

[0052] Preparation method of organic manure: Pig manure and wheat straw are mixed at a weight ratio of 1.5:1. The initial moisture content is adjusted to 60-70%. Anti-clogging aeration pipes are laid at the bottom, piled up and covered with film for aerobic fermentation. The intelligent control system is activated. When the pile temperature rises above 65℃, it automatically forces ventilation to cool down. When it drops below 40℃, ventilation is stopped. The organic manure is obtained after 28 days of aerobic fermentation. The organic matter content of the organic manure is 35.2%, the seed germination index is 85%, the humic acid content is 22.6%, the total nutrients are 5.1%, the moisture content is 28.5%, and the mass ratio of humic acid to fulvic acid is 1.45:1.

[0053] Soil with an organic matter content of 11.2 g / kg, a pH of 7.6, and a bulk density of 1.54 g / cm³ was selected. 3 The soil is soil that needs improvement.

[0054] (1) When harvesting winter wheat, use a cutting and crushing device to crush the wheat straw to a length of ≤10 cm and a stubble height of ≤8 cm. Then, spread the crushed straw on the soil to be improved, with a spreading uniformity of >80%. Then, mix the compound straw decomposing bacteria agent with water at a mass-volume ratio of 1:50 g / mL, and spray the compound straw decomposing bacteria agent at a spraying rate of 2 kg / mu on the surface of the wheat straw.

[0055] (2) After harvesting corn, the corn stalks are removed from the field and then organic manure is applied to the soil to be improved at a rate of 13.3 tons / hectare. The soil is then rotary tilled to a depth of 15 cm for mixing. After mixing, the soil is leveled and compacted.

[0056] (3) Repeat step (1).

[0057] (4) After harvesting corn, the corn stalks are removed from the field and then organic manure is applied to the soil to be improved at a rate of 10.64 tons / hectare. The soil is then rotary tilled to a depth of 15 cm for mixing. After mixing, the soil is leveled and compacted.

[0058] (5) Repeat step (1).

[0059] (6) After harvesting corn, the corn stalks are removed from the field and organic manure is applied to the soil to be improved at a rate of 14.63 tons / hectare. The soil is then deeply plowed to a depth of 32 cm using a moldboard plow and mixed. After mixing, the soil is leveled and compacted.

[0060] During the construction of the sponge topsoil layer (years 1-3) and after its completion, a winter wheat-summer maize rotation is implemented annually. Liquid functional fertilizer (5×10⁻⁶) is applied once each during the seedling and jointing stages of each crop. 7(CFU / mL Trichoderma harzianum spores and 8 g / L potassium humate). Topdressing should be applied at 12 L / mu during the seedling stage and 20 L / mu during the jointing stage.

[0061] Example 4 A method for constructing a sponge topsoil layer based on the synergistic return of organic manure and straw to the field: The difference from Example 3 is that the soil to be improved was replaced with soil with an organic matter content of 10.6 g / kg and a bulk density of 1.56 g / cm³. 3 The soil; the amount of organic manure applied in step (2) is 15.6 tons / hectare; the amount of organic manure applied in step (4) is 10.92 tons / hectare; the amount of organic manure applied in step (6) is 18.72 tons / hectare, and the depth of deep plowing is 35 cm; topdressing is carried out at 13 L / mu during the seedling stage and at 22 L / mu during the jointing stage, and the other steps are the same.

[0062] Comparative Example 1 The difference from Example 3 is that in step (1), the compound straw decomposing agent was not sprayed, and the wheat straw was crushed and scattered to cover the soil to be improved and then rotary tilled into the soil to a depth of 15 cm. Steps (2), (4) and (6) were omitted, while the other steps were the same.

[0063] Comparative Example 2 The difference from Example 3 is that steps (1), (3) and (5) are omitted, while the other steps are the same.

[0064] Comparative Example 3 The difference from Example 3 is that the depth of deep soil turning in step (6) is replaced with 20 cm, while the other steps are the same.

[0065] Comparative Example 4 The difference from Example 3 is that the amount of organic manure applied in steps (2), (4) and (6) is 13.3 tons / hectare, while the other steps are the same.

[0066] Comparative Example 5 The difference from Example 3 is that the compound straw decomposing agent sprayed in steps (1), (3) and (5) is replaced with a single Aspergillus niger decomposing agent (containing only Aspergillus niger CGMCC NO.6316, viable count 8×10⁻⁶). 8 (CFU / g, spraying rate remains 2 kg / acre), all other steps are exactly the same.

[0067] Comparative Example 6 The difference from Example 3 is that the compound straw decomposing microbial agent sprayed in steps (1), (3), and (5) omits cellulase and lignin peroxidase, and consists only of Trichoderma harzianum (20 parts), Aspergillus niger (15 parts), and Proteobacterium chrysosporum (15 parts), with a viable count of 3.5 × 10⁻⁶. 9 The CFU / g spraying rate remains 2 kg / acre, and all other steps are exactly the same.

[0068] Experimental Example 1 Eight plots were selected, and a combined surface ditch and underground pipe drainage system was constructed in each plot. The underground pipes were buried 80 cm deep and spaced 8 m apart, covered with permeable geotextile. The surface ditches were set at 50 m intervals, with a depth of 40 cm and a width of 50 cm. A soil moisture monitoring system was also installed to enable intelligent drip irrigation during drought and rapid drainage during flood season. Then, a sponge topsoil layer was constructed on these eight plots according to the methods used in Examples 3-4 and Comparative Examples 1-6, while a winter wheat-summer maize rotation was implemented. After three years, soil and crop indicators were monitored. During the third year of maize planting, a 15-day drought occurred during the large trumpet stage of the summer maize.

[0069] Experimental results show that, after three years of crop rotation using the method described in Example 3 of this invention, simultaneous planting of winter wheat and summer maize resulted in an increase in soil organic matter content from 11.2 g / kg to 13.8 g / kg, an increase of 23.2%; and soil bulk density from 1.54 g / cm³ to 13.8 g / kg. 3 Reduced to 1.40 g / cm³ 3 The soil permeability decreased by 9.1%; the saturated hydraulic conductivity (Ksat) increased from 0.8 cm / h to 1.5 cm / h, an increase of 87.5%; and the field water holding capacity increased from 28.5% to 34.2%, an increase of 20.0%. This indicates that the construction method of the present invention can significantly enhance the soil's water infiltration capacity, forming a sponge topsoil layer with a thickness greater than 30 cm. Moreover, the content of water-stable macroaggregates (>0.25 mm) in the soil increased from 18.5% to 34.2%, an increase of 84.9%, indicating that the soil improved by the construction method of the present invention has formed a stable structural framework, and the sponge topsoil layer has stability. Under heavy rainfall conditions (water volume of 100 mm / h), the surface runoff in Example 3 started at 45 minutes, and the total surface runoff was 12.5 m³. 3 / mu, the time required for the saturated water in the topsoil layer (0-30 cm) to drain (from saturation to field capacity) is 6.2 hours, significantly reducing the risk of waterlogging. Furthermore, during the third year of maize cultivation, under conditions of a 15-day continuous drought during the summer maize tasseling stage, the soil moisture content in the topsoil layer (0-40 cm) in Example 3 was 18.5%, the leaf water potential was -0.85 MPa, and the stomatal conductance was 0.21 mol·m⁻². -2 ·s-1 This indicates that the drought stress on crops has been significantly reduced. Moreover, in the third year of corn planting, the amount of chemical fertilizer applied was reduced by 20% compared with the conventional method, and the amount of irrigation water was reduced by 18%. At the same time, the corn yield increased from the initial 612 kg / mu to 658 kg / mu, an increase of 7.5%.

[0070] In Example 4 of this invention, the method of simultaneously planting winter wheat and summer maize, after 3 years of crop rotation, resulted in an increase in soil organic matter content from 9.6 g / kg to 13.2 g / kg, an increase of 37.5%; and soil bulk density from 1.56 g / cm³ to 13.2 g / kg. 3 Reduced to 1.41 g / cm³ 3 The yield decreased by 10.6%; under the condition of a continuous drought for 15 days during the large trumpet stage of summer corn in the third year, the corn yield increased from the initial 585 kg / mu to 642 kg / mu, an increase of 9.7%.

[0071] The above experimental results show that after three years of improvement using the construction methods of Examples 3 and 4 of this invention, the soil organic matter content increased by more than 23.2%, the soil bulk density decreased by more than 9.1%, the soil saturated hydraulic conductivity increased by 87.5%, and the soil water holding capacity increased by 20.0%. This indicates that the construction method of this invention can significantly enhance the soil's infiltration capacity and water holding capacity, forming a sponge topsoil layer. Furthermore, the content of water-stable large aggregates (>0.25 mm) in the soil increased by 84.9%, indicating that the soil improved by the construction method of this invention forms a stable structural framework, and the sponge topsoil layer possesses stability. Moreover, after the sponge topsoil layer is constructed, the amount of fertilizer applied and irrigation water used is significantly reduced during crop cultivation on the sponge topsoil layer, saving costs while also increasing crop yield.

[0072] However, in Comparative Example 1, when winter wheat and summer maize were planted simultaneously, after 3 years of crop rotation, the soil organic matter content only increased from 11.2 g / kg to 11.8 g / kg, an increase of 5.4%; and the soil bulk density only decreased to 1.53 g / cm³. 3The soil saturated hydraulic conductivity (Ksat) only increased from 0.8 cm / h to 0.9 cm / h; the content of water-stable macroaggregates (>0.25 mm) only increased from 18.5% to 21.2%. Under heavy rainfall conditions (100 mm / h), the surface runoff in Comparative Example 1 started 18 minutes earlier than in Example 3; the total surface runoff was 163% greater than in Example 3; and the time required to drain the saturated water in the topsoil was greater than 24 hours, which was 287% longer than the drainage time in Example 3, indicating that Comparative Example 1 had a significant risk of waterlogging. The results show that conventional straw return to the field in Comparative Example 1 has limited effect on soil improvement and is difficult to achieve rapid construction of a sponge topsoil layer. Furthermore, during the third year of maize cultivation, under a continuous drought of 15 days during the tasseling stage of summer maize, the soil moisture content in the 0-40 cm topsoil layer of Comparative Example 1 decreased by 5.8% compared to Example 3, and the leaf water potential decreased by 0.32 MPa; stomatal conductance decreased by 42% compared to Example 3, indicating that the drought stress on the crop in Comparative Example 1 was greater than that in Example 3. Moreover, during the third year of maize cultivation, management was carried out according to local conventional cultivation methods, with 40 kg / mu of compound fertilizer applied (nitrogen, phosphorus, and potassium contents of 28%, 5%, and 7%, respectively), and the total irrigation volume throughout the growth period was approximately 80 m³. 3 / mu, the irrigation method is sprinkler irrigation, and the corn yield of Comparative Example 1 only increased to 625 kg / mu, an increase of 2.1%.

[0073] Comparative Example 2: Simultaneous planting of winter wheat and summer maize using the same method resulted in a 3-year crop rotation. Soil organic matter content increased from 11.2 g / kg to 12.6 g / kg, an increase of 12.5%; soil bulk density decreased to 1.48 g / cm³. 3 The soil saturated hydraulic conductivity (Ksat) only increased from 0.8 cm / h to 1.1 cm / h; the content of water-stable macroaggregates (>0.25 mm) increased from 18.5% to 26.8%, an increase of 44.9%, which was lower than that of Example 3 (84.9%). The soil field water holding capacity only increased to 31.5%; under heavy rainfall conditions (water volume of 100 mm / h), the reduction in surface runoff (38%) and the time for topsoil to drain (12.5 hours) were both worse than those of Example 3. It can be seen that although the application of organic manure in Comparative Example 2 has a certain soil improvement effect, it lacks the structural support of straw decomposition products and is difficult to form stable macroaggregates. Moreover, in the third year of corn planting, management was carried out according to the local conventional cultivation mode, with the application of compound fertilizer of 40 kg / mu (nitrogen, phosphorus and potassium contents of 28%, 5% and 7% respectively), and the total irrigation volume during the whole growth period was about 80 m³. 3 / mu, irrigation method is sprinkler irrigation. In Comparative Example 2, under the condition of continuous drought for 15 days during the large trumpet stage of summer maize, the maize seasonal yield increased to 642 kg / mu, an increase of 4.9%. The results show that the effect of applying organic manure alone is better than conventional straw return to the field, but lower than the combined application of organic manure and straw, indicating that the combined application of straw and organic manure in this invention has a significant synergistic effect.

[0074] Comparative Example 3, when winter wheat and summer maize were planted simultaneously using the same method, resulted in a 3-year crop rotation. After this rotation, the soil organic matter content increased from 11.2 g / kg to 12.9 g / kg, an increase of 15.2%; the soil bulk density decreased to 1.46 g / cm³. 3 The soil saturated hydraulic conductivity (Ksat) only increased to 1.1 cm / h; the content of water-stable macroaggregates (>0.25 mm) only increased to 25.6%. Soil field water holding capacity only increased to 30.8%, an increase of 8.1%, lower than the 20.0% in Example 3. Under heavy rainfall conditions (100 mm / h), due to the lack of a continuous water-conducting channel between the topsoil and the 80 cm buried underground pipe (obstruction by the plow pan), the time required to drain the saturated water in the topsoil was as long as 15.8 hours, far exceeding that of Example 3 (6.2 hours), failing to achieve an effective "storage-drainage" synergistic effect. The results indicate that although soil organic matter increased, the insufficient thickness of the topsoil (only 20 cm) resulted in limited effective water storage capacity. Therefore, the improvement in field water holding capacity and drainage effect were far inferior to Example 3, failing to achieve a true "sponge" effect. Furthermore, in the third year of corn planting, management was carried out according to local conventional cultivation methods, with 40 kg / mu of compound fertilizer applied (nitrogen, phosphorus, and potassium contents of 28%, 5%, and 7%, respectively), and the total irrigation volume for the entire growth period was approximately 80 m³. 3 / mu, the irrigation method is sprinkler irrigation. Under the condition of continuous drought for 15 days during the big trumpet stage of summer maize, the maize seasonal yield increased to 632 kg / mu, an increase of 8%.

[0075] Compared with Example 3, the effects of applying equal amounts of organic manure in Comparative Example 4 on soil topsoil organic matter content, saturated hydraulic conductivity, and crop yield are shown in Table 1 below.

[0076] Table 1 Comparison of the effects of differentiated fertilization and equal-amount fertilization

[0077] As shown in Table 1, Example 3 of this invention reduced the total input of organic manure by 3.3%. However, many key indicators in the soil topsoil of this invention were superior to those of Comparative Example 4, which applied the same amount of organic manure. In particular, Example 3 improved the increase in deep organic matter and the saturated water conductivity of the topsoil by 50% and 15.4% respectively compared to Comparative Example 4, reflecting the significantly improved water conduction and storage capacity of the sponge topsoil structure of this invention. This indicates that although Comparative Example 4, with its equal application method, had a higher total input, it failed to achieve optimal spatial distribution of organic matter. This invention, employing a differentiated fertilization strategy of medium-low-high levels, through precise regulation of "second-round reduction and utilization of residues, and third-round increase and deep construction," not only saves material costs but, more importantly, significantly enhances the construction effect and function of the sponge topsoil, significantly increasing the organic matter content and water conduction and storage capacity of the soil.

[0078] Compared with Example 3, Comparative Examples 5 and 6 changed the type of microbial agent sprayed on wheat straw. The effects on indicators such as straw decomposition rate, soil water holding capacity, saturated hydraulic conductivity, drought resistance, and flood resistance are shown in Table 2 below.

[0079] Table 2 Comparison of indicators under different microbial agent treatments

[0080] As shown in Table 2, the composite straw decomposing microbial agent of this invention decomposes wheat straw more thoroughly and efficiently. The decomposition products, in synergy with organic manure, form a more stable and developed porous sponge-like tillage layer structure, thus significantly outperforming other microbial agents in core performance aspects such as water retention capacity, water conduction rate, and drought and flood resistance. These results fully demonstrate that this invention achieves a significant synergistic effect through the synergistic interaction of straw and organic fertilizer, the combination of microorganisms and enzymes, and the combination of rotary tillage and deep plowing.

[0081] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for constructing a sponge topsoil layer based on the synergistic return of organic manure and straw to the field, characterized in that, Includes the following steps: S1: Spread wheat straw on the soil to be improved, then spray compound straw decomposing bacteria on the wheat straw, and apply organic manure to the soil and rotary tillage 3-5 months later. S2: Repeat step S1 after 7-9 months of rotary tillage; S3: After rotary tillage for 7-9 months, spread wheat straw on the soil again, then spray compound straw decomposing bacteria on the wheat straw. After 3-5 months, apply organic manure to the soil and deep plow. The compound straw decomposing microbial agent comprises the following components by weight: 15-25 parts of Trichoderma harzianum, 10-20 parts of Aspergillus niger, 10-20 parts of Protozoa chrysospora, 2-4 parts of cellulase, and 1-3 parts of lignin peroxidase.

2. The construction method according to claim 1, characterized in that, The length of the wheat straw is ≤10 cm; the spraying rate of the compound straw decomposing agent is 1~3 kg / mu; the viable count of Trichoderma harzianum is 5×10⁻⁶. 8 ~2×10 9 CFU / g, the viable count of the Aspergillus niger is 3 × 10⁻⁶. 8 ~1×10 9 CFU / g, the viable count of *Phanerochaete chrysosporium* was 3 × 10⁻⁶. 8 ~1×10 9 The cellulase activity is 5000~30000 U / g, and the lignin peroxidase activity is 500~2000 U / g.

3. The construction method according to claim 1, characterized in that, The organic manure contains 30-40% organic matter, has a seed germination index of 80-90%, a humic acid content of 20-25%, and a humic acid to fulvic acid mass ratio of 1-2:

1.

4. The construction method according to any one of claims 1 to 3, characterized in that, The amount of organic manure applied in S1 is the theoretical application rate F ± 10%, and the formula for calculating the theoretical application rate F is as follows: F=[ΔSOM×H×BD×100] / (OM×η); Where ΔSOM is the difference in organic matter content of the topsoil before and after improvement; H is the target thickness of the topsoil; BD is the bulk density of the soil to be improved; OM is the organic matter content of organic manure; and η is the efficiency coefficient. The amount of organic manure applied in S2 is 0.7 to 0.9 times that in S1; the amount of organic manure applied in S3 is 1.0 to 1.2 times that in S1.

5. The construction method according to claim 4, characterized in that, The value of ΔSOM ranges from 1 to 15 g / kg; the value of H ranges from 30 to 35 cm; and the value of BD ranges from 1.1 to 1.6 g / cm. 3 The value of OM ranges from 30% to 50%, and the value of η ranges from 0.3% to 0.5%.

6. The construction method according to claim 1, characterized in that, The depth of rotary tillage is 12-18 cm; the depth of deep plowing is 30-35 cm.

7. The application of the construction method according to any one of claims 1 to 6 in improving soil water holding capacity and / or improving soil water conduction rate.

8. The application of the construction method according to any one of claims 1 to 6 in increasing soil organic matter content and / or reducing soil bulk density.

9. The application of the construction method according to any one of claims 1 to 6 in reducing fertilizer application and / or reducing irrigation water consumption.

10. The application of the construction method according to any one of claims 1 to 6 in increasing wheat or corn yield.

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