High-activity organic fertilizer for conditioning degraded cultivated land soil structure

Abstract

The invention discloses a high-activity organic fertilizer for conditioning a degraded cultivated land soil structure, and belongs to the technical field of organic fertilizers. Comprising the following components in parts by mass: 20-40 parts of cow dung, 10-20 parts of peanut shells, 10-15 parts of thermoelectric straw ash, 2-5 parts of carboxymethyl chitosan, 0.5-1 part of a silane coupling agent, 3-8 parts of a modified organic fertilizer additive, 0.1-0.5 part of zinc sulfate, 0.3-0.5 part of calcium phosphate and 0.5-1.5 parts of a complex microbial inoculant. Synergistic effects of straw ash, decomposed cow dung, pretreated peanut shells and complex microbial inoculants are utilized to systematically improve degraded cultivated land: organic matters and active silicon are supplemented, and agglomerates are cemented and stabilized; multistage pores are formed, so that the permeability and the pollutant adsorption capacity are improved; the microbial agent secretes cement, fixes nitrogen, winds hyphae and repairs a microbial network. Particularly, a three-dimensional network is formed through coupling of carboxymethyl chitosan and a modified additive containing chelating / hydrophilic groups, so that the fertilizer stability, the nutrient slow release property and the mechanical and water erosion resistance of soil aggregates are enhanced, and long-term optimization of a soil structure and improvement of ecological functions are realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic fertilizer, and particularly relates to a high-activity organic fertilizer for regulating soil structure of degraded farmland. BACKGROUND

[0002] With the continuous improvement of agricultural intensification, long-term high-intensity and unreasonable farming and management measures have led to serious degradation of farmland soil in some regions. Straw off-field, continuous plowing and rotary tillage, single crop monoculture and excessive reliance on chemical fertilizers while neglecting organic fertilizer input, etc. have caused the continuous decline of soil ecological function, which is specifically manifested in the deterioration of soil physical structure, low organic matter content and imbalance of microbial community structure.

[0003] At present, for the improvement and repair of degraded farmland, the commonly used measures include increasing the application of ordinary organic fertilizer, implementing straw returning to field, applying soil structure modifier and microbial inoculant, etc. However, the existing technology still has obvious limitations: ordinary organic fertilizer can supplement organic matter, but its structure regulation speed is slow and its effect on microbial community reconstruction is limited; direct straw returning to field is slow in decomposition in low-temperature regions and it is difficult to form stable aggregates in the short term; chemical modifier has a quick effect, but long-term use may lead to secondary pollution or soil dependence; ordinary microbial inoculant has low survival rate and poor colonization effect in harsh soil environment, and the repair effect is unstable. Therefore, it is urgent to develop a high-activity organic fertilizer which can systematically improve soil structure, rapidly increase organic matter content, activate microbial community and has environmental adaptability, so as to realize the rapid, stable and ecological-friendly repair of degraded farmland soil. SUMMARY

[0004] In view of the above situation, in order to overcome the defects of the prior art, the organic fertilizer disclosed by the application can realize the multiple goals of material complementation, function synergy and ecological repair, and systematically solve the problems of soil structure damage, organic matter decrease and microbial diversity reduction in degraded farmland.

[0005] In order to achieve the above purpose, the following technical scheme is adopted: the application provides a high-activity organic fertilizer for regulating soil structure of degraded farmland, which comprises the following components in mass parts: cattle manure 20-40 parts, peanut shell 10-20 parts, hot electricity straw ash 10-15 parts, carboxymethyl chitosan 2-5 parts, silane coupling agent 0.5-1 part, modified organic fertilizer additive 3-8 parts, zinc sulfate 0.1-0.5 part, calcium phosphate 0.3-0.5 part, and compound microbial inoculant 0.5-1.5 part.

[0006] The modified organic fertilizer additive is prepared by the following steps: (1) By mass, 12-16 parts of benzimidazole-2-acetic acid and 8-10 parts of 1,4-diazacycloheptan-6-ol were added to a reaction flask. Using dimethyl sulfoxide as solvent, 1-2 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride were added. The mixture was heated to 70-85°C under nitrogen protection and stirred for 6-9 hours. The product was poured into ice water to precipitate, filtered, and vacuum dried to obtain the benzimidazole modified monomer. The reaction equation for the preparation of the benzimidazole-modified monomer is as follows: ; (2) By mass, take 10-13 parts of benzimidazole modified monomer and 9-11 parts of 3-chloro-2-hydroxyacrylate and add them to a high-pressure reactor. Add deionized water as solvent, add triethylamine dropwise to adjust the pH of the system to 7.5-8.5, heat to 55-65℃ and react for 5-7 hours. After the reaction is completed, remove the solvent by vacuum distillation, recrystallize with ethyl acetate, filter, and vacuum dry to obtain propylene-modified benzimidazole monomer; The reaction equation for the preparation of the propylene-modified benzimidazole monomer is as follows: ; (3) By mass, 6-9 parts of propylene-modified benzimidazole monomer, 4-6 parts of sodium 3-acrylamidopropanesulfonate, and 2-4 parts of N-hydroxymethylacrylamide are mixed and added to a reaction flask equipped with a reflux condenser. Deionized water is added to prepare a solution with a mass fraction of 30%-40%. After purging with nitrogen for 30 min to remove oxygen, 0.3-0.5 parts of azobisisobutyramidine hydrochloride are added. The temperature is raised to 50-60℃ and reacted for 5-8 h. The product is then dried under vacuum to obtain the modified organic fertilizer additive.

[0007] Furthermore, the cow manure contains 60% organic matter, 1.5% nitrogen, 1.0% phosphorus, and 1.5% potassium. The pretreatment steps for the cow manure include: aerobic composting, maintaining a temperature of 55°C for 5 days.

[0008] Furthermore, the peanut shell contains 25% lignin and 38% cellulose, and the pretreatment steps of the peanut shell include: crushing to 2-5 mm and pre-wetting with 1% urea solution.

[0009] Furthermore, the thermal power plant straw ash is the ash residue produced by burning straw in a thermal power plant, and the thermal power plant straw ash is a mixture composed of thermal power plant straw bottom ash and thermal power plant straw fly ash in a mass ratio of 1:1.

[0010] The bottom ash has a pH of 9-12 and contains K, Ca, and Si elements; the fly ash contains active silicon and trace heavy metals; and the thermal power straw ash serves as a silicon source and binder in organic fertilizer.

[0011] Further, the complex bacterial agent contains bacillus mucilaginosus, azotobacter vinelandii, and trichoderma harzianum, and the viable bacterial count is greater than or equal to 5*10 8 CFU / g.

[0012] Further, the silane coupling agent is one of KH550, KH560 and KH570.

[0013] Further, the organic fertilizer is prepared by the following steps: S1. Coupling reaction: carboxymethyl chitosan and modified organic fertilizer additives are added to a reaction kettle in proportion, deionized water is added and stirred until completely dissolved to prepare a mixed solution with a mass fraction of 10%-15%; a silane coupling agent is mixed with 50% mass fraction of ethanol to obtain a silane coupling agent solution with a mass fraction of 15-20%, and then the silane coupling agent solution is added to the mixed solution, heated to 40-50 DEG C, reacted for 2-3 hours, then filtered and dried to obtain a coupling reaction product; S2. Mixed fermentation: pretreated cow dung, peanut shells and thermal power straw ash, zinc sulfate and calcium phosphate are mixed in proportion, the coupling reaction product is added, stirred uniformly, and then the complex bacterial agent is added to perform temperature control fermentation; S3. Post-ripening drying: the fermented material is placed in a cool and ventilated place for aging for 10 days, and at the same time, the moisture content is reduced to less than or equal to 25%; S4. Quality detection: whether the pH, effective viable bacterial count and heavy metal content meet the standards is determined, and the product is delivered after meeting the standards.

[0014] Further, the temperature control fermentation condition is that the strip pile compost is fermented at a constant temperature of 40 DEG C for 10 days, the pile is turned over once a day to make the oxygen content greater than 15%, and then the tank type high-temperature aerobic fermentation is performed for 7 days.

[0015] Further, the quality detection standard of step S4 is that the pH is 6.5-7.8, the effective viable bacterial count is greater than or equal to 200 million / g, As is less than or equal to 15 mg / kg, and Cd is less than or equal to 0.3 mg / kg.

[0016] The beneficial effects of the present application are: The organic fertilizer disclosed by the application can realize multiple goals of material complementation, function synergy and ecological restoration, and systematically solves problems such as soil structure damage, organic matter reduction and microbial diversity reduction in degraded farmland, wherein the straw ash provides rich silicate cementing materials, can gradually release active silicon in the soil, and promotes the cementation and stability of the aggregate; the cow dung generates humic acid substances after composting fermentation, not only improves the soil's ability to retain fertilizer and water, but also can be used as an organic cementing agent to promote the formation of micro-aggregates and improve the soil porosity; after the peanut shell is crushed and pretreated with urea, the lignin and cellulose components can enhance the structural strength of the organic material, form a stable multi-pore structure in the soil, improve the aeration and water permeability, and effectively adsorb and fix heavy metals and organic pollutants; the gelling bacillus contained in the compound microbial agent can secrete extracellular polysaccharide cementing materials to directly promote the soil particle aggregation; the brown nitrogen-fixing bacteria can supplement biological nitrogen sources and promote the accumulation of organic matter; and the Trichoderma harzianum further stabilizes the aggregate structure through the mycelial winding effect and metabolic products, and jointly repairs the soil microbial network to improve the water stability and ecological function of the aggregate.

[0017] The carboxymethyl chitosan and the modified organic fertilizer aid are coupled by a silane coupling agent to form a three-dimensional network structure, which significantly enhances the overall stability of the organic fertilizer. The structure can optimize the pore distribution of the organic fertilizer after being applied to the soil, and improve the retention and slow-release ability of the organic fertilizer for nutrients and water. The benzimidazole ring and the diazepine structure in the modified organic fertilizer aid have excellent metal ion chelating ability, can combine with calcium, magnesium and other key bridge ions in the soil, and promote the aggregation. The double bond, hydroxyl group introduced by propyleneization, the sulfonic acid group, hydroxyl group and amide group introduced by polymerization, and other hydrophilic functional groups further improve the water solubility and interfacial activity of the aid, so that the aid is more easily dispersed and acts on the soil particle interface. The interpenetrating network structure formed by the aid and the carboxymethyl chitosan through silane coupling can effectively enhance the mechanical stability and water erosion resistance of the soil aggregate, and realize long-term improvement of the soil structure. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The raw materials, products in step (1) and the product in step (2) in Example 3 of the application are as follows: 1 HNMR characterization image; Figure 2 The bar chart of the water-stable aggregate content and the average weight diameter measurement results of each group in the degraded farmland soil structure conditioning test of the application is as follows: Figure 3 The bar chart of the soil total porosity and aeration porosity measurement results of each group in the degraded farmland soil structure conditioning test of the application is as follows: Figure 4 The bar chart of the soil bulk density measurement results of each group in the degraded farmland soil structure conditioning test of the application is as follows: Figure 5 A column chart of the soil organic matter content determination results of each group of soil in the degraded farmland soil structure conditioning test of the present application; Figure 6 A column chart of the actinomycete abundance determination results of each group of soil in the degraded farmland soil structure conditioning test of the present application.

[0019] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate the present application and explain the present application together with the embodiments of the present application, and do not constitute a limitation on the present application. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application are described below clearly and completely. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application, and all other embodiments obtained by those skilled in the art without creative labor based on the embodiments of the present application shall fall within the scope of protection of the present application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method and material similar or equivalent to those described can be applied in the present application. The preferred implementation methods and materials described herein are only for demonstration, but cannot limit the content of the present application.

[0022] The experimental methods in the following embodiments are all conventional methods unless otherwise specified, and the test materials used in the following embodiments are all purchased from commercial channels unless otherwise specified.

[0023] Embodiment 1: A high-activity organic fertilizer for conditioning the soil structure of degraded farmland, comprising the following components in mass parts: Cow dung 20 parts, peanut shell 10 parts, hot electricity straw ash 10 parts, carboxymethyl chitosan 2 parts, silane coupling agent KH550 0.5 parts, modified organic fertilizer additive 3 parts, zinc sulfate 0.1 part, calcium phosphate 0.3 part, and compound microbial agent 0.5 part.

[0024] The modified organic fertilizer additive is prepared by the following steps: (1) 12 parts of benzimidazole-2-acetic acid and 8 parts of 1,4-diazepane-6-ol are added to a reaction flask by mass, dimethyl sulfoxide is used as a solvent, 1 part of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is added, the temperature is raised to 70°C under nitrogen protection, and stirring is carried out for 6h, the product is precipitated in ice water, filtered, and vacuum dried to obtain a benzimidazole modified monomer; (2) 10 parts of benzimidazole modified monomer and 9 parts of 3-chloro-2-hydroxypropyl acrylate by mass were added to a high-pressure reaction kettle, deionized water was used as a solvent, triethylamine was added dropwise to adjust the pH of the system to 7.5, and the temperature was raised to 55°C for 5h of reaction. After the reaction was completed, the solvent was removed by vacuum distillation, recrystallized with ethyl acetate, filtered, and dried under vacuum to obtain propylene benzimidazole modified monomer; (3) 6 parts of propylene benzimidazole modified monomer, 4 parts of 3-acrylamidopropyl sulfonic acid sodium, and 2 parts of N-hydroxymethyl acrylamide by mass were mixed and added to a reaction bottle equipped with a reflux condenser. A 30% mass fraction solution was prepared by adding deionized water. After oxygen was removed by nitrogen for 30 min, 0.3 parts of azobisdimethylaminoformamide hydrochloride was added, and the temperature was raised to 50°C for 5h of reaction. The product was dried under vacuum to obtain a modified organic fertilizer additive.

[0025] The cow dung contains 60% organic matter, 1.5% nitrogen, 1.0% phosphorus, and 1.5% potassium. The pretreatment step of the cow dung includes aerobic composting at 55°C for 5 days. The peanut shell contains 25% lignin and 38% cellulose. The pretreatment step of the peanut shell includes crushing to 2-5mm and pre-wetting with 1% urea solution. The thermoelectric straw ash is a mixture of thermoelectric straw bottom ash and thermoelectric straw fly ash in a mass ratio of 1:1. The complex microbial agent contains Bacillus mucilaginosus, Azotobacter chroococcum, and Trichoderma harzianum, with a viable bacterial count of ≥5×10 8 CFU / g.

[0026] The organic fertilizer is prepared by the following steps: S1. Coupling reaction: Carboxymethyl chitosan and modified organic fertilizer additive were added to a reaction kettle in proportion, deionized water was added and stirred until completely dissolved to prepare a mixed solution with a mass fraction of 10%. Silane coupling agent was mixed with 50% mass fraction of ethanol to obtain a 15% mass fraction of silane coupling agent solution, which was then added to the mixed solution. The temperature was raised to 40°C, and the reaction was carried out for 2h. Then, the product was filtered and dried to obtain the coupling reaction product. S2. Mixed fermentation: The pretreated cow dung, peanut shell, and thermoelectric straw ash, zinc sulfate, and calcium phosphate were mixed in proportion, and the coupling reaction product was added. After stirring uniformly, the complex microbial agent was added, and temperature-controlled fermentation was carried out. The temperature-controlled fermentation conditions were as follows: pile composting at 40°C for 10 days, with pile turning once a day to maintain an oxygen content of >15%, followed by tank-type high-temperature aerobic fermentation for 7 days. S3. Post-mature drying: The fermented material was placed in a cool and ventilated place for aging for 10 days, while the moisture content was reduced to ≤25%. S4. Quality detection: The pH, effective viable bacterial count, and heavy metal content were measured to determine whether they met the standards. The quality detection standards were as follows: pH 6.5-7.8, effective viable bacterial count ≥200 million / g, As ≤15mg / kg, Cd ≤0.3mg / kg. The product met the standards and was ready for delivery.

[0027] Embodiment 2: A high-activity organic fertilizer for conditioning the structure of degraded farmland soil, comprising the following components by mass fraction: 40 parts of cow dung, 20 parts of peanut shells, 15 parts of thermal power straw ash, 5 parts of carboxymethyl chitosan, 1 part of silane coupling agent KH560, 8 parts of modified organic fertilizer additive, 0.5 parts of zinc sulfate, 0.5 parts of calcium phosphate, and 1.5 parts of compound microbial agent.

[0028] The modified organic fertilizer additive is prepared by the following steps: (1) 16 parts of benzimidazole-2-acetic acid and 10 parts of 1,4-diazepane-6-ol are added to a reaction flask by mass, dimethyl sulfoxide is used as the solvent, 2 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is added, and the temperature is raised to 85°C under nitrogen protection, stirring for 9h, the product is precipitated in ice water, filtered, and vacuum dried to obtain a benzimidazole modified monomer; (2) 13 parts of benzimidazole modified monomer and 11 parts of 3-chloro-2-hydroxypropyl acrylate are taken by mass, deionized water is used as the solvent, triethylamine is added dropwise to adjust the pH of the system to 8.5, the temperature is raised to 65°C, and the reaction is carried out for 7h, after the reaction is completed, the solvent is removed by vacuum distillation, recrystallized with ethyl acetate, filtered, and vacuum dried to obtain a propylene benzimidazole modified monomer; (3) 9 parts of propylene benzimidazole modified monomer, 6 parts of 3-acrylamidopropyl sodium sulfonate, and 4 parts of N-hydroxymethyl acrylamide are mixed, added to a reaction bottle equipped with a reflux condenser, and deionized water is added to prepare a 40% mass fraction solution, oxygen is removed by nitrogen for 30min, 0.5 parts of azobisdimethylaminoformamide hydrochloride is added, the temperature is raised to 60°C, and the reaction is carried out for 8h, the product is vacuum dried to obtain a modified organic fertilizer additive.

[0029] The cow dung contains 60% organic matter, 1.5% nitrogen, 1.0% phosphorus, and 1.5% potassium, the pretreatment steps of the cow dung include: aerobic composting, maintaining at 55°C for 5 days; the peanut shells contain 25% lignin and 38% cellulose, the pretreatment steps of the peanut shells include: crushing to 2-5mm, and pre-wetting with 1% urea solution; the thermal power straw ash is a mixture composed of thermal power straw bottom ash and thermal power straw fly ash in a mass ratio of 1:1; the compound microbial agent contains Bacillus mucilaginosus, Azotobacter chroococcum, and Trichoderma harzianum, with a viable bacterial count of ≥5×10 8 CFU / g.

[0030] The organic fertilizer is prepared by the following steps: S1. Coupling reaction: carboxymethyl chitosan and modified organic fertilizer additives are added to the reaction kettle in proportion, deionized water is stirred to dissolve completely, and a mixed solution with a mass fraction of 15% is prepared; the silane coupling agent is mixed with 50% mass fraction of ethanol to obtain a 20% mass fraction of silane coupling agent solution, and then the silane coupling agent solution is added to the mixed solution, heated to 50℃, reacted for 3h, then filtered and dried to obtain the coupling reaction product; S2. Mixed fermentation: pretreated cow dung, peanut shell and thermal power straw ash, zinc sulfate, calcium phosphate are mixed in proportion, the coupling reaction product is added, stirred uniformly, then the compound microbial inoculum is added, and temperature control fermentation is carried out. The temperature control fermentation conditions are: 40℃ constant temperature fermentation for 10 days, pile turning once a day, oxygen content > 15%, then tank type high temperature aerobic fermentation for 7 days; S3. Post-mature drying: the fermented material is placed in a cool and ventilated place for aging for 10 days, and the moisture content is reduced to ≤25% at the same time; S4. Quality detection: whether the pH, effective viable bacterial count and heavy metal content meet the standard is determined, and the quality detection standard is: pH 6.5-7.8, effective viable bacterial count ≥ 200 million / g, As ≤ 15 mg / kg, Cd ≤ 0.3 mg / kg, and the product is qualified and put into the warehouse.

[0031] Example 3: A high-activity organic fertilizer for regulating the structure of degraded farmland soil, comprising the following components by mass fraction: 30 parts of cow dung, 15 parts of peanut shell, 12 parts of thermal power straw ash, 3 parts of carboxymethyl chitosan, 0.6 parts of silane coupling agent KH570, 5 parts of modified organic fertilizer additive, 0.3 parts of zinc sulfate, 0.4 parts of calcium phosphate, and 1 part of compound microbial inoculum.

[0032] The modified organic fertilizer additive is prepared by the following steps: (1) 14 parts of benzimidazole-2-acetic acid and 9 parts of 1,4-diazepane-6-ol are added to a reaction flask by mass, dimethyl sulfoxide is used as a solvent, 1.5 parts of 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride is added, heated to 75℃ under nitrogen protection, stirred for 7h, the product is precipitated in ice water, filtered, and vacuum dried to obtain benzimidazole modified monomer; (2) 12 parts of benzimidazole modified monomer and 10 parts of 3-chloro-2-hydroxypropyl acrylate are taken by mass, added to a high-pressure reaction kettle, deionized water is used as a solvent, triethylamine is added dropwise to adjust the pH of the system to 8.0, heated to 60℃ for 6h, after the reaction is completed, the solvent is removed by vacuum distillation, recrystallized with ethyl acetate, filtered, and vacuum dried to obtain propylene benzimidazole modified monomer; (3) 7 parts of propylene benzimidazole modified monomer, 5 parts of 3-acrylamidopropanesulfonic acid sodium, and 3 parts of N-hydroxymethyl acrylamide by mass were mixed, added to a reaction bottle equipped with a reflux condenser, and prepared into a solution with a mass fraction of 35% by adding deionized water. After oxygen was removed by nitrogen for 30 min, 0.4 parts of azobisdimethylamidine hydrochloride was added, and the temperature was raised to 55°C for 6 h of reaction. The product was dried under vacuum to obtain the modified organic fertilizer adjuvant.

[0033] The cow dung contains 60% organic matter, 1.5% nitrogen, 1.0% phosphorus, and 1.5% potassium. The pretreatment step of the cow dung includes aerobic composting at 55°C for 5 days. The peanut shell contains 25% lignin and 38% cellulose. The pretreatment step of the peanut shell includes crushing to 2-5 mm and pre-wetting with 1% urea solution. The thermoelectric straw ash is a mixture of thermoelectric straw bottom ash and thermoelectric straw fly ash at a mass ratio of 1:1. The compound microbial agent contains Bacillus mucilaginosus, Azotobacter chroococcum, and Trichoderma harzianum, with a viable bacterial count of ≥5×10 8 CFU / g.

[0034] The organic fertilizer is prepared by the following steps: S1. Coupling reaction: carboxymethyl chitosan and modified organic fertilizer adjuvant are added to a reaction kettle in proportion, deionized water is added and stirred until completely dissolved to prepare a mixed solution with a mass fraction of 12%; silane coupling agent is mixed with 50% mass fraction of ethanol to obtain a silane coupling agent solution with a mass fraction of 18%, which is then added to the mixed solution, heated to 45°C, and reacted for 2.5 h, followed by filtration and drying to obtain the coupling reaction product; S2. Mixed fermentation: pretreated cow dung, peanut shell, and thermoelectric straw ash, zinc sulfate, and calcium phosphate are mixed in proportion, and the coupling reaction product is added. After stirring uniformly, the compound microbial agent is added, and temperature-controlled fermentation is carried out. The temperature-controlled fermentation conditions are as follows: pile composting at 40°C for 10 days, with pile turning once a day to maintain an oxygen content of >15%, followed by tank-type high-temperature aerobic fermentation for 7 days; S3. Post-mature drying: the fermented material is placed in a cool and ventilated place for aging for 10 days, while the moisture content is reduced to ≤25%; S4. Quality detection: determine whether the pH, effective viable bacterial count, and heavy metal content meet the standards. The quality detection standards are as follows: pH 6.5-7.8, effective viable bacterial count ≥200 million / g, As ≤15 mg / kg, Cd ≤0.3 mg / kg. After meeting the standards, the product is ready for delivery.

[0035] Comparative Example 1: The difference between this comparative example and Example 3 is that the organic fertilizer component lacks carboxymethyl chitosan and silane coupling agent, and the rest is the same as Example 3.

[0036] Comparative Example 2: The difference between this comparative example and Example 3 is that the modified organic fertilizer additive and the silane coupling agent are absent in the organic fertilizer component, and the rest is the same as Example 3.

[0037] Comparative Example 3: The difference between this comparative example and Example 3 is that the complex microbial agent is absent in the organic fertilizer component, and the rest is the same as Example 3.

[0038] Result analysis The raw materials in step (1) and the product in step (2) in Example 3 of the present application were characterized by nuclear magnetic resonance hydrogen spectrum, and the results are shown in Figure 1 , wherein (a), (b), (c), (d) respectively refer to benzimidazole-2-acetic acid, 1,4-diazepane-6-ol, benzimidazole modified monomer, propylene benzimidazole modified monomer. It can be seen from Figure 1 , (a) 12.42 ppm is the proton peak of the carboxyl group in benzimidazole-2-acetic acid, 12.16 ppm is the proton peak of the secondary amine in benzimidazole-2-acetic acid, (b) 5.02 ppm is the proton peak of the hydroxyl group in 1,4-diazepane-6-ol, 3.70 ppm is the proton peak of the secondary amine group in 1,4-diazepane-6-ol, in (c) the proton peaks of the carboxyl and hydroxyl groups disappear, and the remaining characteristic peaks are retained in the product of step (2), indicating that benzimidazole-2-acetic acid and 1,4-diazepane-6-ol are successfully esterified to synthesize benzimidazole modified monomer; in (d) the proton peak of the secondary amine group of the diazepane structure disappears, a hydroxyl proton peak appears at 5.38 ppm, and multiple proton peaks on C=C appear in the range of 5.8-6.4 ppm, indicating that benzimidazole modified monomer and 3-chloro-2-hydroxypropyl acrylate are successfully synthesized to synthesize propylene benzimidazole modified monomer.

[0039] In order to verify the conditioning effect of the high-activity organic fertilizer of the present application on the structure of degraded cultivated land, a field plot test was conducted on a typical degraded cultivated land (soil type is black calcareous soil, initial state is: organic matter content 2.1%, water stable aggregate (WR0.25) content 25%, soil bulk density 1.45 g / cm 3 ).

[0040] The following treatment groups were set, each treatment group was set with 3 repetitions, and a randomized block arrangement was adopted: Blank control group: no organic fertilizer was applied; Example group and comparative example group: the organic fertilizer prepared in the corresponding group was applied, and the application amount was 3000 kg / ha.

[0041] All organic fertilizers were applied as base fertilizer in a single application before sowing and mixed into the 0-20cm topsoil layer using rotary tillage. The blank control group underwent rotary tillage simultaneously, and subsequent field management (including irrigation, weeding, etc.) was completely identical across all plots.

[0042] Soil samples from the 0-20cm topsoil layer were collected before fertilization (0 days), 90 days after fertilization, and 180 days after fertilization. The samples were mixed, air-dried, and sieved for the determination of various indicators.

[0043] The content and mean weight diameter (MWD) of water-stable aggregates >0.25 mm (WR0.25) were determined by wet sieving. The results are shown in [Figure number missing]. Figure 2 The total porosity and aeration porosity of the soil were determined using the ring sampler method. The results are shown in [Figure number missing]. Figure 3 Soil bulk density was determined using the ring sampler method; the results are shown below. Figure 4 The soil organic matter (SOM) content was determined using the potassium dichromate oxidation-external heating method. The results are shown below. Figure 5 Actinomycete abundance was determined using the dilution plating method, and the results were expressed as colony forming units (CFU / g) per gram of dry soil. See the attached table for details. Figure 6 .

[0044] from Figures 2-6 As can be seen, the soil indicators of all experimental groups applying organic fertilizer showed a continuous improvement trend over time, while the blank control group showed no significant change. Comparative Example 1 lacked carboxymethyl chitosan and silane coupling agent, resulting in the failure to form an effective three-dimensional network structure in the organic fertilizer. Its soil aggregate stability and nutrient retention capacity were significantly lower than those in Example 3, indicating that the structural framework formed by carboxymethyl chitosan after silane coupling plays a key role in improving soil mechanical stability and water erosion resistance. Comparative Example 2 lacked modified organic fertilizer adjuvant and silane coupling agent, resulting in insufficient metal ion chelation and cementation capacity in its soil, and poor aggregate formation rate and stability. This indicates that the benzimidazole and diazacycloheptane structures and the functional group diversity brought about by polymerization modification in the modified organic fertilizer adjuvant are crucial for promoting calcium-magnesium bond bridge formation and interfacial bonding. Comparative Example 3 lacked compound microbial agent. Although soil organic matter was improved, the improvement in microbial activity and actinomycete abundance was limited, indicating that compound microbial agent is irreplaceable in rapidly activating soil microbial communities and enhancing aggregate water stability and ecological function. In summary, the present invention, through the synergistic system constructed by carboxymethyl chitosan, silane coupling agent, modified organic fertilizer adjuvant and compound microbial agent, can simultaneously and significantly optimize the physical structure of soil (including reducing bulk density, increasing porosity and promoting aggregation), improve soil fertility (increasing soil organic matter content) and activate the soil ecosystem (increasing actinomycete abundance), thus achieving systematic restoration of degraded farmland.

[0045] While embodiments of the application have been shown and described, it is to be understood that the application is not limited to the details of the embodiments described, since various modifications can be made by those skilled in the art, without departing from the spirit and scope of the application, which is defined by the appended claims and their equivalents.

[0046] The above description of the application and its embodiments is not restrictive, and the embodiments shown are only one of the embodiments of the application, and the actual application is not limited thereto. In general, if a person skilled in the art is inspired by it, without departing from the purpose of the application, without creative design, similar ways and embodiments of the technical solution should belong to the protection scope of the application.

Claims

1. A highly active organic fertilizer for conditioning the soil structure of degraded arable land, characterized in that: The components include the following parts by weight: 20-40 parts cow dung, 10-20 parts peanut shells, 10-15 parts thermal power plant straw ash, 2-5 parts carboxymethyl chitosan, 0.5-1 part silane coupling agent, 3-8 parts modified organic fertilizer adjuvant, 0.1-0.5 parts zinc sulfate, 0.3-0.5 parts calcium phosphate, and 0.5-1.5 parts compound microbial agent; The modified organic fertilizer adjuvant is prepared through the following steps: (1) By mass, 12-16 parts of benzimidazole-2-acetic acid and 8-10 parts of 1,4-diazacycloheptan-6-ol were added to a reaction flask. Using dimethyl sulfoxide as solvent, 1-2 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride were added. The mixture was heated to 70-85°C under nitrogen protection and stirred for 6-9 hours. The product was poured into ice water to precipitate, filtered, and vacuum dried to obtain the benzimidazole modified monomer. (2) By mass, take 10-13 parts of benzimidazole modified monomer and 9-11 parts of 3-chloro-2-hydroxyacrylate and add them to a high-pressure reactor. Add deionized water as solvent, add triethylamine dropwise to adjust the pH of the system to 7.5-8.5, heat to 55-65℃ and react for 5-7 hours. After the reaction is completed, remove the solvent by vacuum distillation, recrystallize with ethyl acetate, filter, and vacuum dry to obtain propylene-modified benzimidazole monomer; (3) By mass, 6-9 parts of propylene-modified benzimidazole monomer, 4-6 parts of sodium 3-acrylamidopropanesulfonate, and 2-4 parts of N-hydroxymethylacrylamide are mixed and added to a reaction flask equipped with a reflux condenser. Deionized water is added to prepare a solution with a mass fraction of 30%-40%. After purging with nitrogen for 30 min to remove oxygen, 0.3-0.5 parts of azobisisobutyramidine hydrochloride are added. The temperature is raised to 50-60℃ and reacted for 5-8 h. The product is then dried under vacuum to obtain the modified organic fertilizer additive.

2. The highly active organic fertilizer for conditioning degraded arable land soil structure according to claim 1, characterized in that: The cow manure contains 60% organic matter, 1.5% nitrogen, 1.0% phosphorus, and 1.5% potassium. The pretreatment steps for the cow manure include: aerobic composting, maintaining a temperature of 55°C for 5 days.

3. The highly active organic fertilizer for conditioning degraded arable land soil structure according to claim 1, characterized in that: The peanut shell contains 25% lignin and 38% cellulose. The pretreatment steps of the peanut shell include: crushing to 2-5 mm and pre-wetting with 1% urea solution.

4. The highly active organic fertilizer for conditioning degraded arable land soil structure according to claim 1, characterized in that: The thermal power plant straw ash is a mixture of thermal power plant straw bottom ash and thermal power plant straw fly ash in a mass ratio of 1:

1.

5. The highly active organic fertilizer for conditioning degraded arable land soil structure according to claim 1, characterized in that: The compound microbial agent contains Bacillus mucilaginosus, azotobacter cyanobacterium, and Trichoderma harzianum, with a viable count ≥ 5 × 10⁻⁶. 8 CFU / g.

6. The highly active organic fertilizer for conditioning degraded arable land soil structure according to claim 1, characterized in that: The silane coupling agent is one of KH550, KH560, and KH570.

7. The highly active organic fertilizer for conditioning degraded arable land soil structure according to claim 1, characterized in that: The organic fertilizer is prepared through the following steps: S1. Coupling reaction: Carboxymethyl chitosan and modified organic fertilizer additives are added to a reaction vessel in proportion, and deionized water is added and stirred until completely dissolved to prepare a mixed solution with a mass fraction of 10%-15%; silane coupling agent is mixed with 50% mass fraction ethanol to obtain a silane coupling agent solution with a mass fraction of 15-20%; the silane coupling agent solution is then added to the mixed solution, the temperature is raised to 40-50℃, and the reaction is carried out for 2-3 hours. After filtration and drying, the coupling reaction product is obtained. S2. Mixed fermentation: Pretreated cow manure, peanut shells, thermal power plant straw ash, zinc sulfate, and calcium phosphate are mixed in proportion, coupled reaction products are added, and after stirring evenly, compound microbial agents are added for temperature-controlled fermentation. S3. Post-fermentation drying: Place the fermented material in a cool, ventilated place to age for 10 days, while reducing the moisture content to ≤25%; S4. Quality Inspection: Determine whether the pH, effective viable bacteria count and heavy metal content meet the standards, and release the product after it meets the standards.

8. The highly active organic fertilizer for conditioning degraded arable land soil structure according to claim 7, characterized in that: The temperature-controlled fermentation conditions are as follows: windrow composting at a constant temperature of 40℃ for 10 days, with the pile turned over once a day to ensure an oxygen content >15%, followed by high-temperature aerobic fermentation in tanks for 7 days.

9. The highly active organic fertilizer for conditioning degraded arable land soil structure according to claim 7, characterized in that: The quality testing standards for step S4 are: pH 6.5-7.8, effective viable bacteria count ≥ 200 million / g, As ≤ 15mg / kg, Cd ≤ 0.3mg / kg.

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