An organic fertilizer for conditioning the soil structure of degraded arable land

Abstract

This invention discloses a highly active organic fertilizer for conditioning the soil structure of degraded arable land, belonging to the field of organic fertilizer technology. It comprises the following components in parts by weight: 20-40 parts cow manure, 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. Through the synergistic effect of straw ash, well-rotted cow manure, pretreated peanut shells, and compound microbial agent, it systematically improves degraded arable land: replenishing organic matter and active silicon, cementing and stabilizing aggregates; forming multi-level pores, improving permeability and pollutant adsorption capacity; and the microbial agent secretes cementing substances, fixes nitrogen, and entangles mycelia, repairing the microbial network. In particular, by coupling carboxymethyl chitosan with modified additives containing chelating / hydrophilic groups to form a three-dimensional network, fertilizer stability, nutrient slow release, and the mechanical and water erosion resistance of soil aggregates are enhanced, thereby achieving long-term optimization of soil structure and improvement of ecological function.

Description

Technical Field

[0001] This invention belongs to the field of organic fertilizer technology, and in particular relates to a highly active organic fertilizer for conditioning the soil structure of degraded arable land. Background Technology

[0002] With the increasing intensification of agriculture, long-term high-intensity and unreasonable farming and management practices have led to serious degradation of arable land soil in some areas. Production methods such as straw removal from the field, continuous plowing and rotary tillage, monoculture, and over-reliance on chemical fertilizers while neglecting the input of organic fertilizers have caused a continuous decline in soil ecological function, specifically manifested in the deterioration of soil physical structure, low organic matter content, and imbalance of microbial community structure.

[0003] Currently, common measures for the improvement and restoration of degraded arable land include increasing the application of ordinary organic fertilizers, promoting straw return to the field, and applying soil structure improvers and microbial agents. However, existing technologies still have significant limitations: while ordinary organic fertilizers can replenish organic matter, their structural conditioning speed is slow and their effect on microbial community reconstruction is limited; direct straw return to the field decomposes slowly in low-temperature regions, making it difficult to form stable aggregates in the short term; although chemical improvers are effective quickly, long-term use may lead to secondary pollution or soil dependence; ordinary microbial agents have low survival rates and poor colonization effects in harsh soil environments, resulting in unstable restoration effects. Therefore, there is an urgent need to develop a highly active organic fertilizer that can systematically improve soil structure, rapidly increase organic matter content, activate microbial communities, and possess environmental adaptability, in order to achieve rapid, stable, and eco-friendly restoration of degraded arable land. Summary of the Invention

[0004] In response to the above situation and to overcome the shortcomings of the prior art, the organic fertilizer disclosed in this invention can achieve multiple goals of material complementarity, functional synergy and ecological restoration, and systematically address the problems of soil structure damage, organic matter decline and microbial diversity reduction in degraded arable land.

[0005] To achieve the above objectives, the following technical solution is adopted: This invention provides a highly active organic fertilizer for conditioning the soil structure of degraded arable land, comprising the following components in parts by weight:

[0006] 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 additive, 0.1-0.5 parts zinc sulfate, 0.3-0.5 parts calcium phosphate, and 0.5-1.5 parts compound microbial agent.

[0007] The modified organic fertilizer adjuvant is prepared through the following steps:

[0008] (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.

[0009] The reaction equation for the preparation of the benzimidazole-modified monomer is as follows:

[0010] ;

[0011] (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;

[0012] The reaction equation for the preparation of the propylene-modified benzimidazole monomer is as follows:

[0013] ;

[0014] (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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] Furthermore, the compound microbial agent contains Bacillus mucilaginosus, azotobacter cyanobacterium, and Trichoderma harzianum, with a viable count ≥ 5 × 10⁻⁶. 8 CFU / g.

[0020] Furthermore, the silane coupling agent is one of KH550, KH560, and KH570.

[0021] Furthermore, the organic fertilizer is prepared through the following steps:

[0022] 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.

[0023] 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.

[0024] 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%;

[0025] 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.

[0026] Furthermore, the temperature-controlled fermentation conditions are as follows: windrow composting at a constant temperature of 40°C for 10 days, with the pile turned over once a day to ensure an oxygen content >15%, followed by high-temperature aerobic fermentation in a tank for 7 days.

[0027] Furthermore, the quality testing standards for step S4 are: pH 6.5-7.8, effective viable bacteria count ≥ 200 million / g, As ≤ 15mg / kg, and Cd ≤ 0.3mg / kg.

[0028] The beneficial effects of this invention are:

[0029] The organic fertilizer disclosed in this invention can achieve multiple goals of material complementarity, functional synergy, and ecological restoration, systematically addressing problems such as soil structure damage, organic matter decline, and reduced microbial diversity in degraded farmland. Straw ash provides abundant silicate cementing substances, which can gradually release active silicon in the soil, promoting the cementation and stabilization of aggregates. Cow manure, after composting and fermentation, generates humic acids, which not only enhance the soil's water and fertilizer retention capacity but also act as an organic cementing agent to promote the formation of micro-aggregates and improve soil looseness. Peanut shells, after crushing and pretreatment with urea... After processing, its lignin and cellulose components can enhance the structural strength of organic materials, forming a stable multi-level porous structure in the soil, improving aeration and water permeability, and effectively adsorbing and fixing heavy metals and organic pollutants; the Bacillus mucilaginosus contained in the compound microbial agent can secrete extracellular polysaccharide cementing substances, directly promoting soil particle aggregation; brown nitrogen-fixing bacteria can supplement biological nitrogen sources and promote organic matter accumulation; Trichoderma harzianum further stabilizes the aggregate structure through hyphal entanglement and metabolites, jointly repairing the soil microbial network and improving the water stability and ecological function of the aggregates.

[0030] Carboxymethyl chitosan and modified organic fertilizer adjuvants undergo a coupling reaction via a silane coupling agent to form a three-dimensional network structure, significantly enhancing the overall stability of the organic fertilizer. This structure optimizes the pore distribution of the organic fertilizer after application to the soil, improving its ability to retain and slowly release nutrients and water. The benzimidazole ring and diazacycloheptanane structure in the modified organic fertilizer adjuvant possess excellent metal ion chelating ability, which can combine with calcium, magnesium, and other bond-bridge ions in the soil, promoting aggregation. The introduction of double bonds and hydroxyl groups through propyleneation facilitates subsequent free radical polymerization reactions, while the hydrophilic functional groups such as sulfonic acid groups, hydroxyl groups, and amide groups introduced by polymerization further improve the water solubility and interfacial activity of the adjuvant, making it easier to disperse and act on the soil particle interface. The interpenetrating network structure constructed by the adjuvant and carboxymethyl chitosan through silane coupling can effectively enhance the mechanical stability and water erosion resistance of soil aggregates, achieving long-term improvement of soil structure. Attached Figure Description

[0031] Figure 1 The raw materials and products in step (1) and the products in step (2) of Embodiment 3 of the present invention. 1 HNMR characterization images;

[0032] Figure 2 This is a bar chart showing the results of measuring the content and average weight diameter of water-stable aggregates in each group during the soil structure conditioning experiment of degraded arable land in this invention.

[0033] Figure 3 This is a bar chart showing the results of measuring total soil porosity and aeration porosity in each group during the soil structure conditioning experiment of degraded arable land in this invention.

[0034] Figure 4This is a bar chart showing the soil bulk density measurement results of each group in the soil structure conditioning experiment of degraded arable land of this invention;

[0035] Figure 5 This is a bar chart showing the soil organic matter content determination results of each group in the degraded arable land soil structure conditioning experiment of this invention;

[0036] Figure 6 This is a bar chart showing the results of actinomycete abundance determination in each group during the soil structure conditioning experiment of degraded arable land in this invention.

[0037] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0040] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the experimental materials used in the following examples are all purchased from commercial channels.

[0041] Example 1: A highly active organic fertilizer for conditioning the soil structure of degraded arable land, comprising the following components in parts by weight:

[0042] 20 parts cow dung, 10 parts peanut shells, 10 parts thermal power plant straw ash, 2 parts carboxymethyl chitosan, 0.5 parts silane coupling agent KH550, 3 parts modified organic fertilizer additive, 0.1 parts zinc sulfate, 0.3 parts calcium phosphate, and 0.5 parts compound microbial agent.

[0043] The modified organic fertilizer adjuvant is prepared through the following steps:

[0044] (1) By mass, 12 parts of benzimidazole-2-acetic acid and 8 parts of 1,4-diazacycloheptan-6-ol were added to a reaction flask. Using dimethyl sulfoxide as solvent, 1 part of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride was added. The mixture was heated to 70°C under nitrogen protection and stirred for 6 hours. The product was poured into ice water to precipitate, filtered, and dried under vacuum to obtain the benzimidazole modified monomer.

[0045] (2) By mass, 10 parts of benzimidazole modified monomer and 9 parts of 3-chloro-2-hydroxy propylene acrylate were added to a high-pressure reactor, deionized water was added as solvent, triethylamine was added dropwise to adjust the pH of the system to 7.5, the temperature was raised to 55℃ and the reaction was carried out for 5 hours. After the reaction was completed, the solvent was removed by vacuum distillation, recrystallized with ethyl acetate, filtered, and vacuum dried to obtain propylene-modified benzimidazole monomer;

[0046] (3) By mass, 6 parts of propylene-modified benzimidazole monomer, 4 parts of sodium 3-acrylamidopropanesulfonate and 2 parts of N-hydroxymethylacrylamide were mixed and added to a reaction flask equipped with a reflux condenser. Deionized water was added to prepare a solution with a mass fraction of 30%. After purging with nitrogen for 30 min to remove oxygen, 0.3 parts of azobisisobutyramidine hydrochloride were added. The temperature was raised to 50℃ and reacted for 5 h. The product was dried under vacuum to obtain the modified organic fertilizer additive.

[0047] 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 at 55℃ for 5 days. The peanut shells contain 25% lignin and 38% cellulose. The pretreatment steps for the peanut shells include crushing to 2-5mm and pre-wetting with a 1% urea solution. 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 1:1 mass ratio. The compound microbial agent contains Bacillus mucilaginosus, azotobacter brownii, and Trichoderma harzianum, with a viable count ≥5×10⁻⁶. 8 CFU / g.

[0048] The organic fertilizer is prepared through the following steps:

[0049] S1. Coupling reaction: Carboxymethyl chitosan and modified organic fertilizer additives were added to a reaction vessel in proportion, and 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 ethanol to obtain a 15% mass fraction silane coupling agent solution, and then the silane coupling agent solution was added to the mixed solution, heated to 40℃, reacted for 2 hours, and then filtered and dried to obtain the coupling reaction product;

[0050] S2. Mixed fermentation: Pretreated cow manure, peanut shells, thermal power straw ash, zinc sulfate, and calcium phosphate are mixed in proportion, and coupling reaction products are added. After stirring evenly, compound microbial agents are added for temperature-controlled fermentation. Temperature-controlled fermentation conditions: windrow composting is carried out at a constant temperature of 40℃ for 10 days, with the pile turned over once a day to ensure that the oxygen content is >15%. Then, it is carried out in a tank at high temperature for 7 days.

[0051] 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%;

[0052] S4. Quality Inspection: Determine whether the pH, effective viable bacteria count and heavy metal content meet the standards. The quality inspection standards are: pH 6.5-7.8, effective viable bacteria count ≥200 million / g, As ≤15mg / kg, Cd ≤0.3mg / kg. Products can be released from the warehouse after meeting the standards.

[0053] Example 2: A highly active organic fertilizer for conditioning the soil structure of degraded arable land, comprising the following components in parts by weight:

[0054] 40 parts cow dung, 20 parts peanut shells, 15 parts thermal power plant straw ash, 5 parts carboxymethyl chitosan, 1 part silane coupling agent KH560, 8 parts modified organic fertilizer additives, 0.5 parts zinc sulfate, 0.5 parts calcium phosphate, and 1.5 parts compound microbial agent.

[0055] The modified organic fertilizer adjuvant is prepared through the following steps:

[0056] (1) By mass, 16 parts of benzimidazole-2-acetic acid and 10 parts of 1,4-diazacycloheptan-6-ol were added to a reaction flask. Using dimethyl sulfoxide as solvent, 2 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride were added. The mixture was heated to 85°C under nitrogen protection and stirred for 9 hours. The product was poured into ice water to precipitate, filtered, and dried under vacuum to obtain the benzimidazole modified monomer.

[0057] (2) By mass, 13 parts of benzimidazole modified monomer and 11 parts of 3-chloro-2-hydroxy propylene acrylate were added to a high-pressure reactor, deionized water was added as solvent, triethylamine was added dropwise to adjust the pH of the system to 8.5, the temperature was raised to 65℃ and the reaction was carried out for 7 hours. After the reaction was completed, the solvent was removed by vacuum distillation, recrystallized with ethyl acetate, filtered, and vacuum dried to obtain propylene-modified benzimidazole monomer;

[0058] (3) By mass, 9 parts of propylene-modified benzimidazole monomer, 6 parts of sodium 3-acrylamidopropanesulfonate and 4 parts of N-hydroxymethylacrylamide were mixed and added to a reaction flask equipped with a reflux condenser. Deionized water was added to prepare a solution with a mass fraction of 40%. After purging with nitrogen for 30 min to remove oxygen, 0.5 parts of azobisisobutyramidine hydrochloride were added. The temperature was raised to 60℃ and reacted for 8 h. The product was dried under vacuum to obtain the modified organic fertilizer additive.

[0059] 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 at 55℃ for 5 days. The peanut shells contain 25% lignin and 38% cellulose. The pretreatment steps for the peanut shells include crushing to 2-5mm and pre-wetting with a 1% urea solution. 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 1:1 mass ratio. The compound microbial agent contains Bacillus mucilaginosus, azotobacter brownii, and Trichoderma harzianum, with a viable count ≥5×10⁻⁶. 8 CFU / g.

[0060] The organic fertilizer is prepared through the following steps:

[0061] S1. Coupling reaction: Carboxymethyl chitosan and modified organic fertilizer additives were added to a reaction vessel in proportion, and deionized water was added and stirred until completely dissolved to prepare a mixed solution with a mass fraction of 15%; silane coupling agent was mixed with 50% mass fraction ethanol to obtain a 20% mass fraction silane coupling agent solution, and then the silane coupling agent solution was added to the mixed solution, heated to 50℃, reacted for 3 hours, and then filtered and dried to obtain the coupling reaction product;

[0062] S2. Mixed fermentation: Pretreated cow manure, peanut shells, thermal power straw ash, zinc sulfate, and calcium phosphate are mixed in proportion, and coupling reaction products are added. After stirring evenly, compound microbial agents are added for temperature-controlled fermentation. Temperature-controlled fermentation conditions: windrow composting is carried out at a constant temperature of 40℃ for 10 days, with the pile turned over once a day to ensure that the oxygen content is >15%. Then, it is carried out in a tank at high temperature for 7 days.

[0063] 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%;

[0064] S4. Quality Inspection: Determine whether the pH, effective viable bacteria count and heavy metal content meet the standards. The quality inspection standards are: pH 6.5-7.8, effective viable bacteria count ≥200 million / g, As ≤15mg / kg, Cd ≤0.3mg / kg. Products can be released from the warehouse after meeting the standards.

[0065] Example 3: A highly active organic fertilizer for conditioning the soil structure of degraded arable land, comprising the following components in parts by weight:

[0066] 30 parts cow dung, 15 parts peanut shells, 12 parts thermal power plant straw ash, 3 parts carboxymethyl chitosan, 0.6 parts silane coupling agent KH570, 5 parts modified organic fertilizer additive, 0.3 parts zinc sulfate, 0.4 parts calcium phosphate, and 1 part compound microbial agent.

[0067] The modified organic fertilizer adjuvant is prepared through the following steps:

[0068] (1) By mass, 14 parts of benzimidazole-2-acetic acid and 9 parts of 1,4-diazacycloheptan-6-ol were added to a reaction flask. Using dimethyl sulfoxide as solvent, 1.5 parts of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride were added. The mixture was heated to 75°C under nitrogen protection and stirred for 7 h. The product was poured into ice water to precipitate, filtered, and dried under vacuum to obtain the benzimidazole modified monomer.

[0069] (2) By mass, 12 parts of benzimidazole modified monomer and 10 parts of 3-chloro-2-hydroxy propylene acrylate were added to a high-pressure reactor, deionized water was added as solvent, triethylamine was added dropwise to adjust the pH of the system to 8.0, the temperature was raised to 60℃ and the reaction was carried out for 6 hours. After the reaction was completed, the solvent was removed by vacuum distillation, recrystallized with ethyl acetate, filtered, and vacuum dried to obtain propylene-modified benzimidazole monomer;

[0070] (3) By mass, 7 parts of propylene-modified benzimidazole monomer, 5 parts of sodium 3-acrylamidopropanesulfonate and 3 parts of N-hydroxymethylacrylamide were mixed and added to a reaction flask equipped with a reflux condenser. Deionized water was added to prepare a solution with a mass fraction of 35%. After purging with nitrogen for 30 min to remove oxygen, 0.4 parts of azobisisobutyramidine hydrochloride were added. The temperature was raised to 55℃ and reacted for 6 h. The product was dried under vacuum to obtain the modified organic fertilizer additive.

[0071] 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 at 55℃ for 5 days. The peanut shells contain 25% lignin and 38% cellulose. The pretreatment steps for the peanut shells include crushing to 2-5mm and pre-wetting with a 1% urea solution. 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 1:1 mass ratio. The compound microbial agent contains Bacillus mucilaginosus, azotobacter brownii, and Trichoderma harzianum, with a viable count ≥5×10⁻⁶. 8 CFU / g.

[0072] The organic fertilizer is prepared through the following steps:

[0073] S1. Coupling reaction: Carboxymethyl chitosan and modified organic fertilizer additives were added to a reaction vessel in proportion, and deionized water was added and stirred until completely dissolved to prepare a mixed solution with a mass fraction of 12%; silane coupling agent was mixed with 50% mass fraction ethanol to obtain an 18% mass fraction silane coupling agent solution, and then the silane coupling agent solution was added to the mixed solution, heated to 45℃, reacted for 2.5h, filtered, and dried to obtain the coupling reaction product;

[0074] S2. Mixed fermentation: Pretreated cow manure, peanut shells, thermal power straw ash, zinc sulfate, and calcium phosphate are mixed in proportion, and coupling reaction products are added. After stirring evenly, compound microbial agents are added for temperature-controlled fermentation. Temperature-controlled fermentation conditions: windrow composting is carried out at a constant temperature of 40℃ for 10 days, with the pile turned over once a day to ensure that the oxygen content is >15%. Then, it is carried out in a tank at high temperature for 7 days.

[0075] 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%;

[0076] S4. Quality Inspection: Determine whether the pH, effective viable bacteria count and heavy metal content meet the standards. The quality inspection standards are: pH 6.5-7.8, effective viable bacteria count ≥200 million / g, As ≤15mg / kg, Cd ≤0.3mg / kg. Products can be released from the warehouse after meeting the standards.

[0077] 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, while the rest are the same as Example 3.

[0078] Comparative Example 2: The difference between this comparative example and Example 3 is that the organic fertilizer component lacks the modified organic fertilizer adjuvant and silane coupling agent, while the rest are the same as Example 3.

[0079] Comparative Example 3: The difference between this comparative example and Example 3 is that the organic fertilizer component lacks the compound microbial agent, while the rest are the same as Example 3.

[0080] Results Analysis

[0081] The raw materials and products in step (1) and step (2) of Example 3 of this invention were characterized by proton nuclear magnetic resonance spectroscopy. The results are shown in [Figure number missing]. Figure 1 Where (a), (b), (c), and (d) refer to benzimidazole-2-acetic acid, 1,4-diazacycloheptane-6-ol, benzimidazole-modified monomer, and propylene-modified benzimidazole monomer, respectively. Figure 1As can be seen from the data, in (a) the proton peak at 12.42 ppm is the proton peak on the carboxyl group of benzimidazole-2-acetic acid, and the proton peak at 12.16 ppm is the proton peak on the secondary amine group of benzimidazole-2-acetic acid; in (b) the proton peak at 5.02 ppm is the proton peak on the hydroxyl group of 1,4-diazacycloheptan-6-ol, and the proton peak at 3.70 ppm is the proton peak on the secondary amine group of 1,4-diazacycloheptan-6-ol; in (c) the proton peaks on the carboxyl and hydroxyl groups disappear, while the remaining characteristic peaks are retained in step (…). 2) The product indicates that the esterification reaction of benzimidazole-2-acetic acid and 1,4-diazacycloheptane-6-ol successfully synthesized the benzimidazole modified monomer; in (d), the proton peak on the secondary amino group of the diazacycloheptane structure disappeared, and a hydroxyl proton peak appeared at 5.38 ppm. Multiple proton peaks appeared on C=C in the range of 5.8-6.4 ppm, indicating that the benzimidazole modified monomer and propyl 3-chloro-2-hydroxyacrylate successfully synthesized the propylene-modified benzimidazole modified monomer.

[0082] To verify the conditioning effect of the highly active organic fertilizer of this invention on the soil structure of degraded arable land, a typical degraded arable land (soil type: black calcareous soil, initial state: organic matter content 2.1%, water-stable aggregate (WR0.25) content 25%, soil bulk density 1.45 g / cm³) was tested. 3 Field plot trials were conducted.

[0083] The following processing groups are set up, each with 3 replicates, and randomized block arrangement is used:

[0084] Blank control group: No organic fertilizer was applied;

[0085] Example group and comparative group: The organic fertilizer prepared in the corresponding group was applied at a rate of 3000 kg / hectare.

[0086] 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.

[0087] 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.

[0088] 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 The abundance of actinomycetes was determined by 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 .

[0089] 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.

[0090] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0091] The present invention and its embodiments have been described above. This description is not restrictive, and the embodiments shown are only one of the embodiments of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. An organic fertilizer for conditioning the structure of degraded cultivated soil, characterized in that it comprises: Components comprising the following parts by mass: Cattle manure 20-40 parts, peanut shells 10-20 parts, thermal power straw ash 10-15 parts, carboxymethyl chitosan 2-5 parts, silane coupling agent 0.5-1 part, modified organic fertilizer adjuvant 3-8 parts, zinc sulfate 0.1-0.5 parts, calcium phosphate 0.3-0.5 parts, compound microbial agent 0.5-1.5 parts; The modified organic fertilizer adjuvant is prepared by the following steps: (1) According to the mass, 12-16 parts of benzimidazole-2-acetic acid and 8-10 parts of 1,4-diazepane-6-alcohol are added to a reaction flask with dimethyl sulfoxide as the solvent, 1-2 parts of 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride is added, and the temperature is raised to 70-85°C under nitrogen protection, and stirred for 6-9h. The product is precipitated in ice water, filtered, and vacuum dried to obtain benzimidazole modified monomer; (2) According to the mass, 10-13 parts of benzimidazole modified monomer and 9-11 parts of 3-chloro-2-hydroxypropyl acrylate are added to a high-pressure reaction kettle with deionized water as the solvent, triethylamine is added dropwise to adjust the system pH to 7.5-8.5, and the temperature is raised to 55-65°C for 5-7h. 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) According to the mass, 6-9 parts of propylene benzimidazole modified monomer, 4-6 parts of 3-acrylamidopropyl sodium sulfonate, and 2-4 parts of N-hydroxymethyl acrylamide are mixed and added to a reaction bottle equipped with a reflux condenser. Deionized water is added to prepare a 30%-40% mass fraction solution. After oxygen is removed by nitrogen for 30min, 0.3-0.5 parts of azobisdimethylaminoformamide hydrochloride is added, and the temperature is raised to 50-60°C for 5-8h. The product is vacuum dried to obtain the modified organic fertilizer adjuvant.

2. The organic fertilizer for conditioning the structure of degraded cultivated soil according to claim 1, characterized in that: The cattle manure contains 60% organic matter, 1.5% nitrogen, 1.0% phosphorus, and 1.5% potassium. The pretreatment steps of the cattle manure include aerobic composting at 55°C for 5 days.

3. The organic fertilizer for conditioning the structure of degraded cultivated soil according to claim 1, characterized in that: 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.

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

1.

5. The organic amendment to condition degraded farmland soil structure of claim 1, wherein: The complex microbial agent contains Bacillus mucilaginosus, Azotobacter chroococcum, Trichoderma harzianum, and the number of live bacteria is ≥5×10 8 CFU / g.

6. The organic amendment to condition degraded farmland soil structure of claim 1, wherein: The silane coupling agent is one of KH550, KH560, and KH570.

7. The organic amendment to condition degraded farmland soil structure of claim 1, wherein: 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 10%-15%; the silane coupling agent is mixed with 50% mass fraction ethanol to obtain a 15-20% mass fraction silane coupling agent solution, which is then added to the mixed solution, heated to 40-50°C, and reacted for 2-3h, then filtered and dried to obtain the coupling reaction product; S2. Mixed fermentation: The pretreated cattle manure, peanut shells, and thermal power 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 for temperature-controlled fermentation. S3. Post-ripening drying: the fermented material is placed in a cool and ventilated place for 10 days, while the moisture content is reduced to ≤25%; S4. Quality detection: the pH, effective viable count and heavy metal content are measured to determine whether they meet the standards, and the product is released after meeting the standards.

8. The organic amendment to condition degraded farmland soil structure of claim 7, wherein: The temperature-controlled fermentation conditions are: 40℃ constant temperature fermentation of the windrow compost for 10 days, with pile turning once a day to make the oxygen content >15%, followed by tank-type high-temperature aerobic fermentation for 7 days.

9. The organic amendment to condition degraded farmland soil structure of claim 7, wherein: The quality detection standards in step S4 are: pH 6.5-7.8, effective viable count ≥200 million / g, As ≤15 mg / kg, Cd ≤0.3 mg / kg.

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