Organic agricultural nutrient management method combining natural minerals and organic fertilizers

Abstract

The invention relates to the technical field of agricultural fertilizers, and discloses an organic agricultural nutrient management method combining natural mineral substances and organic fertilizers, which comprises the following steps: S1, pretreatment of natural mineral substances: crushing zeolite, bentonite and ground phosphate rock, and activating the ground phosphate rock; s2, pretreatment of the organic fertilizer, wherein livestock manure compost and green manure powder are subjected to mixed fermentation; and S3, preparation of composite particles: taking the pretreated organic fertilizer as a core layer to form particles. Through layered particle structure design based on the'adsorption slow release dynamic regulation theory 'and in combination with the characteristics of natural minerals and organic fertilizers, dynamic matching of nutrient release and crop requirements is successfully realized, the utilization efficiency and the lasting period of the fertilizer are remarkably improved, the volatilization and loss of nutrients are reduced, and the yield of crops is increased. Meanwhile, the problem of low utilization rate of phosphorus is solved through the activation of the ground phosphate rock and the chelation of humic acid.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural fertilizers, in particular to an organic agricultural nutrient management method combining natural minerals and organic fertilizers. Background Art

[0002] The rapid development of modern agriculture has increased food production, but has also brought about a series of problems such as soil degradation, inefficient nutrient utilization and environmental pollution. Although long-term reliance on the application of chemical fertilizers has met the growth needs of crops in the short term, it has led to an imbalance in the soil ecosystem, and problems such as a decrease in soil organic matter and a decline in microbial diversity have become increasingly prominent. In this context, exploring more sustainable nutrient management methods, especially the combination of natural minerals and organic fertilizers, has become an important direction for solving agricultural resource waste and environmental pressure.

[0003] Natural minerals (such as zeolite, bentonite, phosphate rock powder, etc.) have been initially applied in agriculture due to their natural nutrient slow-release ability and good soil regulation. In particular, phosphate rock powder, as a slow-release phosphorus source, can gradually release effective phosphorus under acidic conditions. However, the solubility of phosphate rock powder is significantly limited in neutral and alkaline soils, resulting in a significant reduction in its fertilizer effect. In addition, minerals usually have strong adsorption, but this adsorption will also limit the release rate of certain nutrients, which may cause insufficient nutrient supply in the middle and late stages of crop growth.

[0004] On the other hand, the application of organic fertilizers (such as livestock manure and green manure) can significantly improve the physical and biological structure of the soil, increase the content of soil organic matter, and enhance the water retention and aeration of the soil. However, the nutrient concentration of organic fertilizers themselves is low, and the decomposition rate is affected by a variety of environmental factors, which often leads to excessive nutrient release in the early stage and insufficient supply in the later stage. In addition, due to the lack of an effective slow-release regulation mechanism, the application of organic fertilizers alone is likely to cause leaching and loss of nutrients such as nitrogen, phosphorus, and potassium after rainfall, which not only wastes resources but also increases the risk of agricultural non-point source pollution.

[0005] Although preliminary methods of combining natural minerals with organic fertilizers, such as simple mixing or composite granules, have been proposed in the prior art, these technologies have obvious limitations. The lack of dynamic regulation of nutrient release rate leads to excessive release in the early stage or insufficient supply in the later stage; when phosphate rock powder is not effectively treated, its dissolution efficiency in non-acidic soil is low, which seriously affects the utilization rate of fertilizer; in addition, granular fertilizers are easily lost in the soil or decompose prematurely, making it difficult to ensure long-term fertilizer effectiveness. These technical difficulties not only limit the comprehensive effectiveness of natural minerals and organic fertilizers, but also fail to meet the dynamic demand for nutrient supply throughout the entire process of crop growth.

[0006] In existing research and applications, although attempts have been made to improve nutrient release through granulation and slow-release material coating, the single-level fertilizer design has failed to effectively solve the imbalance of nutrient release. At the same time, the existing technology mostly uses chemical means to modify minerals such as phosphate rock powder, but these methods often bring the risk of secondary pollution, or cause fertilizers to combine with metal ions in the soil to form insoluble salts, further reducing the effectiveness of nutrients. In general, the existing technology lacks a comprehensive technical solution that can take into account the release of fast-acting nutrients, the supply of slow-release nutrients, and environmental friendliness.

[0007] Therefore, in view of the above problems in the combined application of natural minerals and organic fertilizers, the present invention proposes an organic agricultural nutrient management method combining natural minerals and organic fertilizers. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention provides an organic agricultural nutrient management method combining natural minerals and organic fertilizers, which solves the problems of unbalanced nutrient release, low utilization efficiency and high environmental pollution risk when natural minerals and organic fertilizers are used in combination.

[0009] To achieve the above objectives, the present invention is implemented by the following technical scheme: an organic agricultural nutrient management method combining natural minerals and organic fertilizers, comprising the following steps: S1. Pretreatment of natural minerals, including crushing of zeolite, bentonite and phosphate rock powder, and activation of phosphate rock powder; S2. Pretreatment of organic fertilizers, including mixed fermentation of livestock manure compost and green manure powder; S3. Preparation of composite particles, comprising: Using pre-treated organic fertilizer as the core layer, granules are formed; The core particles are coated with a mixture of pre-treated phosphate rock powder and bentonite to form an intermediate layer; A mixture of zeolite and chitosan solution is coated outside the middle layer to form a protective layer; S4, drying and cooling the prepared composite particles to obtain a composite slow-release fertilizer; S5. Apply base fertilizer and topdressing fertilizer in stages according to crop needs.

[0010] Preferably, the pretreatment of natural minerals in step S1 includes: S1.1, crush zeolite, bentonite and phosphate rock powder into particle sizes of 0.1-0.5 mm respectively; S1.2. Use a 1%-2% dilute phosphoric acid solution to activate the phosphate rock powder. The activation time is 30-60 minutes and the activation temperature is 25-35°C.

[0011] Preferably, the pretreatment of the organic fertilizer in step S2 includes: S2.1. Mix livestock manure and green manure powder in a weight ratio of 8:2-9:1; S2.2. Fermentation is carried out through high-temperature composting process, the fermentation temperature is 55-65℃, the fermentation time is 10-15d, the moisture content of the compost is maintained at 50%-60% during the fermentation period, and the frequency of turning the compost is once every 2-3d.

[0012] Preferably, the preparation of the core layer of the composite particles in step S3 includes: Using fermented organic fertilizer as the basic raw material; Mixing 10%-15% bentonite and 1%-2% chitosan solution by weight; Core particles with a diameter of 1-2 mm were formed by a disc granulator.

[0013] Preferably, the preparation of the composite particle intermediate layer in step S3 includes: Mix phosphate rock powder and bentonite in a weight ratio of 1:1-2:1; Spray the humic acid solution to combine the mixture with the core particles; The intermediate sustained-release layer with a thickness of 1-2 mm was formed by disk granulation.

[0014] Preferably, the preparation of the composite particle protective layer in step S3 includes: Evenly spraying the zeolite powder with the chitosan solution to form a mixture; The mixture is coated on the outside of the middle layer to form an outer layer with a thickness of 0.5-1 mm.

[0015] Preferably, the composite particles are dried in step S4 by a low-temperature drying process, with a drying temperature of 40-50° C. and a drying time of 4-6 hours.

[0016] Preferably, the method for applying basal fertilizer in step S5 comprises: Apply the composite particles evenly into the soil before sowing, with a fertilization depth of 10-15cm; The application rate is 60-100 kg per mu.

[0017] Preferably, the method for applying topdressing in step S5 comprises: In the middle of crop growth, use strip or furrow application; Apply the composite particles near the root zone at a depth of 5-10 cm; The application rate is 30-50 kg per mu.

[0018] The present invention provides an organic agricultural nutrient management method combining natural minerals and organic fertilizers, which has the following beneficial effects: 1. The present invention adopts a layered particle structure design based on the "dynamic regulation theory of adsorption and slow release", combines the different nutrient release characteristics of natural minerals and organic fertilizers, and realizes the synchronization of nutrient release rate and crop demand through the phased release of the core layer, the slow-release middle layer and the protective outer layer. Compared with the problem that mixed fertilizers in the prior art cannot match the needs of the crop growth cycle, this technical solution solves the defects of too fast release of fast-acting nutrients and insufficient supply of slow-acting nutrients, effectively improves the fertilizer utilization efficiency and reduces the frequency of fertilization.

[0019] 2. The present invention can effectively reduce nitrogen volatilization and the loss of phosphorus and potassium elements through the high adsorption and ion exchange properties of natural minerals such as zeolite and bentonite, and the slow-release regulation function of the chitosan protective layer. Compared with the problem of common granular fertilizers in the prior art that are easily leached and nutrients are lost quickly during the rainy season, the present technical solution significantly enhances the soil nutrient retention capacity and extends the fertilizer effect to 90-120 days, thereby continuously supplying nutrients for the middle and late stages of crop growth.

[0020] 3. The present invention uses the complex design of the intermediate slow-release layer and the chelation effect of humic acid on phosphorus to avoid the problem that the phosphate rock powder easily forms insoluble salts with calcium and iron ions in the soil when it is directly applied. Compared with the technical bottlenecks of low utilization rate of phosphate rock powder and insufficient supply of phosphorus nutrients in the later stage in the prior art, the present invention solves the problems of slow release rate and low effectiveness of phosphorus, and significantly improves the absorption and utilization of phosphorus by crops.

[0021] 4. The present invention adopts the synergistic compounding of natural minerals and organic fertilizers, combined with the functional additives of humic acid and chitosan, which not only provides slow-release nutrients for crops, but also improves the physical structure and aggregate stability of the soil. At the same time, the adsorption characteristics of zeolite and bentonite regulate the rhizosphere microenvironment and promote the activity of beneficial microorganisms. Unlike the existing technology that only focuses on the use of chemical fertilizers leading to soil structure degradation and decreased microbial diversity, this technical solution can significantly improve the soil ecological environment while increasing production, achieving the goal of sustainable agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A flow chart of the organic agricultural nutrient management method of the present invention; Figure 2 The present invention is a flow chart of the method for preparing the composite particles. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Please refer to the attached Figure 1 -Attached Figure 2 The embodiment of the present invention provides an organic agricultural nutrient management method combining natural minerals and organic fertilizers, comprising the following steps: S1. Pretreatment of natural minerals, including crushing of zeolite, bentonite and phosphate rock powder, and activation of phosphate rock powder; S2. Pretreatment of organic fertilizers, including mixed fermentation of livestock manure compost and green manure powder; S3. Preparation of composite particles, comprising: Using pre-treated organic fertilizer as the core layer, granules are formed; The core particles are coated with a mixture of pre-treated phosphate rock powder and bentonite to form an intermediate layer; A mixture of zeolite and chitosan solution is coated outside the middle layer to form a protective layer; S4, drying and cooling the prepared composite particles to obtain a composite slow-release fertilizer; S5. Apply base fertilizer and topdressing fertilizer in stages according to crop needs.

[0025] The pretreatment of natural minerals in step S1 includes: S1.1, crush zeolite, bentonite and phosphate rock powder into particle sizes of 0.1-0.5 mm respectively; S1.2. Use a 1%-2% dilute phosphoric acid solution to activate the phosphate rock powder. The activation time is 30-60 minutes and the activation temperature is 25-35°C.

[0026] The pretreatment of organic fertilizer in step S2 includes: S2.1. Mix livestock manure and green manure powder in a weight ratio of 8:2-9:1; S2.2. Fermentation is carried out through high-temperature composting process, the fermentation temperature is 55-65℃, the fermentation time is 10-15d, the moisture content of the compost is maintained at 50%-60% during the fermentation period, and the frequency of turning the compost is once every 2-3d.

[0027] The preparation of the composite particle core layer in step S3 includes: Using fermented organic fertilizer as the basic raw material; Mixing 10%-15% bentonite and 1%-2% chitosan solution by weight; Core particles with a diameter of 1-2 mm were formed by a disc granulator.

[0028] The preparation of the composite particle intermediate layer in step S3 includes: Mix phosphate rock powder and bentonite in a weight ratio of 1:1-2:1; Spray the humic acid solution to combine the mixture with the core particles; The intermediate sustained-release layer with a thickness of 1-2 mm was formed by disk granulation.

[0029] The preparation of the composite particle protective layer in step S3 includes: Evenly spraying the zeolite powder with the chitosan solution to form a mixture; The mixture is coated on the outside of the middle layer to form an outer layer with a thickness of 0.5-1 mm.

[0030] In step S4, the composite particles are dried using a low-temperature drying process, with a drying temperature of 40-50° C. and a drying time of 4-6 hours.

[0031] The method for applying basal fertilizer in step S5 includes: Apply the composite particles evenly into the soil before sowing, with a fertilization depth of 10-15cm; The application rate is 60-100 kg per mu.

[0032] The method for applying topdressing in step S5 includes: In the middle of crop growth, use strip or furrow application; Apply the composite particles near the root zone at a depth of 5-10 cm; The application rate is 30-50 kg per mu.

[0033] Example 1: Preparation and use of composite granular slow-release fertilizer 1. Natural mineral pretreatment (1) Take zeolite, bentonite and phosphate rock powder and grind them into a particle size of 0.3 mm using a jet mill; (2) Place the phosphate rock powder in a 1.5% dilute phosphoric acid solution for immersion activation. The activation time is 45 minutes and the activation temperature is 30°C. (3) After activation, dry the phosphate rock powder for later use.

[0034] 2. Organic fertilizer pretreatment (1) Take poultry and livestock manure (pig manure) and green manure powder and mix them in a weight ratio of 9:1; (2) Through compost fermentation, the high temperature section is controlled at 60°C and fermentation is maintained for 10 days; (3) During fermentation, the moisture content of the compost is maintained at 55%. The compost is turned over every two days until it turns dark brown and has no odor.

[0035] 3. Preparation of Composite Particles (1) Using fermented organic fertilizer as the core layer, bentonite (accounting for 12% of the weight of the core layer raw material) and chitosan solution (concentration 1%) were added, and core particles with a diameter of 1.5 mm were made using a disc granulator; (2) Mix the activated phosphate rock powder and bentonite in a weight ratio of 2:1, spray the humic acid solution, and coat the core particles to form an intermediate layer with a thickness of 1.5 mm; (3) Zeolite powder is sprayed with 1.5% chitosan solution to evenly coat the middle layer to form an outer protective layer with a thickness of 0.8 mm; (4) Dry the composite particles at 45°C for 4 hours, cool to room temperature and then package.

[0036] 4. Application of basal fertilizer Before sowing, apply fertilizer into the soil to a depth of 12cm and an amount of 80 kg per mu. The core layer of the composite particles releases quick-acting nutrients to meet the needs of seed germination; the slow-release middle layer continuously supplies phosphorus and cooperates with the outer layer to provide later nutrients.

[0037] Example 2: Fertilization application in different soil environments 1. Natural mineral pretreatment (1) Phosphate rock powder and bentonite are selected as raw materials. Phosphate rock powder is activated by 1% phosphoric acid solution for 30 minutes at 28°C; bentonite is crushed by air flow to 0.2 mm; (2) Mix the two in a weight ratio of 3:1 and set aside.

[0038] 2. Organic fertilizer fermentation (1) Mix poultry and livestock manure (chicken manure) and green manure powder in a weight ratio of 8:2; (2) Control the compost temperature at 55°C, ferment for 12 days, keep the moisture content at 60%, and turn the compost every 3 days; (3) After fermentation is complete, sieve out large impurities and set aside.

[0039] 3. Composite Particle Preparation (1) The core layer is made of fermented organic fertilizer mixed with 10% bentonite and disc granulated into core particles with a diameter of 1 mm; (2) The middle layer uses phosphate rock powder and bentonite, and humic acid solution is evenly sprayed to form a coating layer; (3) The outer layer is covered by zeolite powder sprayed with chitosan solution, eventually forming composite particles with a diameter of 4 mm.

[0040] 4. Application method (1) When used on acidic soil, the fertilizer application rate is 100 kg per mu and the fertilizer application depth is 15 cm; (2) The core layer releases quickly to promote early growth, while the middle layer releases slowly to improve the absorption and utilization rate of phosphorus in acidic soils; (3) The outer layer protects nutrients from being lost, thus reducing the impact of nutrient leaching during the rainy season.

[0041] Example 3: Application of slow-release granular fertilizer in rice cultivation 1. Natural mineral pretreatment (1) Mix zeolite and bentonite in a weight ratio of 2:1 and crush to a particle size of 0.4 mm; (2) The phosphate rock powder was activated by soaking in a 1% dilute phosphoric acid solution for 40 minutes at a temperature of 25°C.

[0042] 2. Organic fertilizer fermentation (1) Mix poultry and livestock manure (duck manure) and green manure powder in a weight ratio of 8.5:1.5; (2) The compost fermentation temperature is controlled at 60°C, the fermentation time is 10 days, the moisture content is 55%, and the turning interval is 2 days; (3) After fermentation is completed, sieve.

[0043] 3. Preparation of Composite Particles (1) The core layer is mainly composed of fermented organic fertilizer, mixed with bentonite (12% by weight), and granulated with 1% chitosan solution, and the diameter is controlled at 1.2 mm; (2) The middle layer is a mixture of phosphate rock powder and bentonite, sprayed with humic acid solution, and the thickness is controlled at 1.8 mm; (3) The outer layer is covered by zeolite powder and chitosan solution to form a protective layer with a thickness of 0.5 mm; (4) The whole granules are dried at 45°C for 5 hours and cooled for later use.

[0044] 4. Application method (1) Apply base fertilizer 15 days before sowing, with a dosage of 90 kg per mu and a fertilizer depth of 12 cm; (2) During the tillering stage, apply topdressing to the rhizosphere in rows, with an application rate of 40 kg per mu and a depth of 6 cm.

[0045] The core layer of the particles releases fast-acting nitrogen, the middle layer continuously provides phosphorus, and the protective layer regulates the environment around the roots, significantly increasing rice yield.

[0046] Example 4: Application of long-term slow-release fertilizer in fruit tree planting 1. Natural mineral pretreatment (1) Take phosphate rock powder and bentonite and grind them into particle size of 0.2 mm respectively; (2) Phosphate rock powder was activated with 1.5% phosphoric acid solution at 30°C for 40 minutes.

[0047] 2. Organic fertilizer fermentation (1) Mix livestock manure (cow dung) and green manure powder in a weight ratio of 9:1; (2) The compost temperature is maintained at 55°C for 15 days, the moisture content is 50%-60%, and the compost is turned every 3 days.

[0048] 3. Composite Particle Preparation (1) The core layer is made by mixing fermented organic fertilizer and bentonite (10% by weight), adding 1% chitosan solution and granulating into granules with a diameter of 1.5 mm; (2) The middle layer is phosphate rock powder and bentonite (weight ratio 1:1), sprayed with humic acid solution to form a coating layer with a thickness of 1.8 mm; (3) The outer layer is covered by zeolite powder sprayed with chitosan solution, and the thickness of the outer layer is 0.6 mm; (4) Granule drying temperature is 45°C and time is 4 hours.

[0049] 4. Application method Before the fruit trees bloom, apply 2 kg per plant at a depth of 20 cm. Apply once every 3 months in the later period. The particles release nutrients layer by layer to meet the long-term nutrient needs of the fruit trees.

[0050] Example 5: Effect of fertilization in dryland crops 1. Raw material processing (1) Activate phosphate rock powder with 1% dilute phosphoric acid for 35 minutes; (2) Crush the zeolite to 0.3 mm and set aside; (3) Organic fertilizer is made by mixing livestock and poultry manure (sheep manure) and green manure powder in a ratio of 8.5:1.5 and composting at a temperature of 55°C for 12 days.

[0051] 2. Composite Particle Preparation (1) The core layer is made of fermented organic fertilizer granules with a diameter of 1.2 mm; (2) The middle layer is made of bentonite and phosphate rock powder, and humic acid solution is sprayed to form a coating; (3) The outer layer is covered with zeolite and chitosan solution; the drying temperature of the whole particles is 45°C.

[0052] 3. Usage (1) For dryland corn planting, apply 90 kg / mu of base fertilizer and 30 kg / mu of topdressing; (2) The core layer of quick-acting fertilizer improves the germination rate, while the middle slow-release layer and outer protective layer cope with the drought environment and ensure the supply of nutrients in the later stage.

[0053] Comparative Example 1: Lack of layered granulation design 1. Natural mineral pretreatment (1) Crush zeolite, bentonite and phosphate rock powder to a particle size of 0.3 mm respectively; (2) The phosphate rock powder was not treated with acid activation but was simply crushed and then mixed.

[0054] 2. Organic fertilizer pretreatment (1) Take poultry and livestock manure and green manure powder and mix them in a weight ratio of 9:1; (2) The compost temperature is controlled at 60°C, the fermentation time is 10 days, and the moisture content is maintained at 55%.

[0055] 3. Composite Particle Preparation (1) The fermented organic fertilizer is directly mixed with minerals without granulating the core layer, middle layer and outer layer; (2) Directly make particles through a mixer with a diameter controlled at 4 mm; (3) Drying temperature: 45°C, drying time: 4 hours.

[0056] Comparative Example 2: Phosphate rock powder is not activated 1. Natural mineral pretreatment (1) Take zeolite and bentonite and crush them to a particle size of 0.2 mm; (2) The phosphate rock powder is not treated with acid activation and is directly mixed with bentonite in a weight ratio of 3:1 for later use.

[0057] 2. Organic fertilizer fermentation (1) Take poultry and livestock manure (chicken manure) and green manure powder and mix them in a weight ratio of 8:2; (2) The compost fermentation temperature is controlled at 55°C and the fermentation time is 12 days.

[0058] 3. Composite Particle Preparation (1) The core layer is made of fermented organic fertilizer and bentonite (10%) mixed into particles with a diameter of 1 mm; (2) The middle layer is a mixture of unactivated phosphate rock powder and bentonite, and the humic acid solution is sprayed on the outside of the core layer; (3) The outer layer is a mixture of zeolite and chitosan solution to form particles with a diameter of 4 mm.

[0059] Comparative Example 3: No chitosan coating added 1. Natural mineral pretreatment (1) Crush zeolite, bentonite and phosphate rock powder to a particle size of 0.4 mm respectively; (2) Phosphate rock powder was activated with 1% dilute phosphoric acid for 40 minutes at 25°C.

[0060] 2. Organic fertilizer fermentation (1) Mix poultry and livestock manure (duck manure) and green manure powder in a weight ratio of 8.5:1.5; (2) The compost temperature is maintained at 60°C and fermented for 10 days, with an interval of 2 days between turning the compost.

[0061] 3. Composite Particle Preparation (1) The core layer is a mixture of fermented organic fertilizer and bentonite, with a diameter controlled at 1.2 mm; (2) The middle layer is a mixture of phosphate rock powder and bentonite in a weight ratio of 2:1, and the humic acid solution is sprayed and coated; (3) The outer layer did not use chitosan solution, but was directly coated with zeolite powder to form particles with a diameter of 4 mm.

[0062] Comparative Example 4: Single-layer granulation design 1. Natural mineral pretreatment (1) Phosphate rock powder and bentonite are crushed to a particle size of 0.2 mm respectively; (2) Phosphate rock powder was activated with 1.5% phosphoric acid solution at 30°C for 40 minutes.

[0063] 2. Organic fertilizer fermentation (1) Mix livestock manure (cow dung) and green manure powder in a weight ratio of 9:1; (2) The compost temperature is maintained at 55°C, fermented for 15 days, and the moisture content is maintained at 60%.

[0064] 3. Composite Particle Preparation (1) The fermented organic fertilizer is directly mixed with natural minerals (phosphate rock powder, bentonite and zeolite) without stratification; (2) After mixing, the mixture was granulated into granules with a diameter of 4 mm using a disc granulator; (3) The drying temperature is 45°C and the drying time is 4 hours.

[0065] Comparative Example 5: The particle size of mineral particles is too large 1. Natural mineral pretreatment (1) Grind phosphate rock powder and bentonite to a particle size of 0.8 mm; (2) The phosphate rock powder was not activated but simply crushed for later use.

[0066] 2. Organic fertilizer fermentation (1) Mix livestock manure (sheep manure) and green manure powder in a weight ratio of 8.5:1.5; (2) The composting temperature is 55°C, the fermentation time is 12 days, and the moisture content is maintained at 55%.

[0067] 3. Composite Particle Preparation (1) The core layer is made of a mixture of fermented organic fertilizer and bentonite, with a diameter of 1.5 mm; (2) The middle layer is a mixture of phosphate rock powder with a particle size of 0.8 mm and bentonite, and then coated with humic acid solution after spraying; (3) The outer layer is zeolite powder sprayed with chitosan solution to form particles with a diameter of 5 mm.

[0068] Experiment 1: Nutrient release accuracy test Experimental purpose: To verify the ability of the layered granulation design to regulate the nutrient release rate and to evaluate the difference between Example 1 and Comparative Example 1 in the nutrient release process.

[0069] Experimental description: Experimental steps: Experimental material preparation: The composite granular fertilizer of Example 1 (layered granulation design).

[0070] The composite granular fertilizer of Comparative Example 1 (no stratified granulation design, mineral and organic fertilizers are directly mixed).

[0071] Blank control group: No fertilizer was added, only the test soil was used.

[0072] Soil preparation: Take neutral loam (pH 6.8) and mix it evenly until the water content reaches 40%. Divide the soil into cylindrical containers with a height of 35 cm and a diameter of 20 cm, and fill each container with 5 kg of soil.

[0073] Three replicates were set up in each group, with a total of 9 soil columns.

[0074] Fertilization treatment: The granular fertilizer of Example 1 and the granular fertilizer of Comparative Example 1 were applied in equal amounts at a rate of 80 kg per mu. No fertilizer was applied to the blank group.

[0075] Spread the fertilizer evenly on the soil surface and cover it with 2 cm of thin soil to simulate field fertilization conditions.

[0076] Sampling and testing: Soil samples were taken from a depth of 10–15 cm every 7 days and tested for nitrogen, phosphorus, and potassium content.

[0077] After sampling, the soil was refilled and the lost water was replenished to maintain the moisture content (controlled at 40%–50%).

[0078] The detection cycle is 90 days, with a total of 13 tests.

[0079] Detection method: Nitrogen content: determined by Kjeldahl method.

[0080] Phosphorus content: Determined by molybdenum blue colorimetry.

[0081] Potassium content: determined by flame photometry.

[0082] Experimental data: Nutrient release accuracy comparison experimental data (nitrogen, phosphorus and potassium content changes over time) Experimental summary: It can be seen from the above experimental structure that the technical design of layered granulation has obviously improved the release curve of nutrients. Example 1 shows that the quick-acting layer releases quickly in the early stage, and the intermediate slow-release layer and the outer protective structure ensure the steady release in the later stage. Compared with Comparative Example 1, the release curve of the embodiment is smoother, especially the release rate of phosphorus and potassium can be maintained for a long time. This layer-by-layer release mode obviously optimizes the matching between nutrient supply and crop demand, and avoids the defect of rapid release of nutrients in the later stage of traditional mixed fertilizer.

[0083] The activation treatment of phosphate rock powder is of great significance for the supply of phosphorus in the medium term. Although the phosphorus release in Comparative Example 1 is relatively high in the early stage, it drops rapidly and is difficult to maintain in the later stage. However, Example 1 shows a sustained phosphorus release capacity after the 21st day, which is closely related to the slow-release design after the activation of phosphate rock powder in the middle layer. The release rate of phosphate rock powder is significantly improved after activation by dilute phosphoric acid. At the same time, the regulatory role of humic acid in the layered design also avoids the immobilization of phosphorus in the soil and maintains a relatively high level of effective phosphorus.

[0084] In Comparative Example 1, due to the lack of a protective layer design, the release rate of potassium is high in the early stage, but rapidly decays over time. The chitosan layer in Example 1 regulates the water entry and ion exchange process, making the release of potassium ions more stable. This regulation mode not only extends the shelf life of the fertilizer, but also reduces the risk of potassium ion loss in the environment. In general, layered granulation achieves a synergistic slow release of multiple nutrients by rationally designing each nutrient layer.

[0085] Experiment 2: Test of activation effect of phosphate rock powder Experimental purpose: To verify the effect of acid activation treatment of phosphate rock on the phosphorus release rate and soil available phosphorus content, and to evaluate the difference in phosphorus release performance between Example 2 and Comparative Example 2.

[0086] Experimental description: Experimental steps: Experimental material preparation: Example 2 Composite granular fertilizer (phosphate rock powder treated with acid activation).

[0087] Comparative Example 2: Composite granular fertilizer (unactivated phosphate rock powder).

[0088] Blank control group: no fertilizer was applied.

[0089] Soil preparation: Acidic soil (pH 5.5–6.0) was taken, air-dried and sieved to a diameter of <2 mm. Each experimental container was filled with 5 kg of soil using a plastic bucket (20 cm in diameter and 30 cm in height).

[0090] Each group was set up with 3 replicates, for a total of 9 treatment buckets.

[0091] Fertilization treatment: Apply fertilizer at the rate of 100 kg per mu, spread evenly on the soil surface and lightly harrow and mix to a depth of 10 cm.

[0092] The blank group was not fertilized and only received the same amount of soil harrowing treatment.

[0093] Experimental setup: To simulate natural planting conditions, the soil was kept moist (water content 40%–50%) and deionized water was sprayed every 3 days to replenish the water lost by evaporation.

[0094] Sampling and testing: Every 14 days, soil samples were taken from a depth of 10–15 cm to determine the available phosphorus content and the cumulative amount of phosphorus released.

[0095] The experiment lasted for 90 days, with 7 samples taken.

[0096] Detection method: Available phosphorus content: determined by Olsen method.

[0097] Cumulative phosphorus release: calculated based on the cumulative increase in available phosphorus at different stages.

[0098] Experimental data: Comparative experimental data of activation effect of phosphate rock powder (change of effective phosphorus content over time) Experimental summary: The acid activation treatment of phosphate rock powder brings about a significant improvement in release performance. From the previous data, the effective phosphorus release level of Example 2 within 14 days and 28 days is much higher than that of Comparative Example 2. The release of unactivated phosphate rock powder is limited in the early stage. This is because the acidic conditions in the soil are not enough to dissolve the untreated phosphate rock powder particles, resulting in low phosphorus utilization efficiency. The acid activation treatment obviously breaks the inherent chemical structure of phosphate rock powder, allowing phosphorus to exist in the soil in a more easily absorbed form, which is particularly important in terms of the balance of nutrient supply.

[0099] The data in the middle and late stages also illustrate the problem. The phosphorus release curve of Example 2 shows a slow downward trend, while that of Comparative Example 2 decays rapidly. For untreated phosphate rock powder, it is easy to combine with calcium and iron ions in the soil to form insoluble phosphates, thereby limiting its long-term effectiveness. The humic acid in Example 2 forms a relatively stable organic-inorganic composite structure with the activated phosphate rock powder. This composite structure can effectively prevent the fixation of phosphorus and control its release rate, ensuring that there is still phosphorus available for crops in the middle and late stages.

[0100] The performance of the blank group is very stable. The background phosphorus content of the acidic soil has hardly changed, which further demonstrates the dominance of fertilizer application in improving phosphorus levels. Although Comparative Example 2 has a slight release in the initial stage, the soil phosphorus content drops rapidly in a short period of time, which obviously cannot meet the later demand. In comparison, the long-term phosphorus supply capacity of Example 2 is undoubtedly more superior. It not only meets the early and mid-term growth of crops, but also provides a guarantee for continuous supply in the later stage. From a mechanistic point of view, this is also fully in line with the expectation of improving the solubility of phosphate rock after acid activation.

[0101] Experiment 3: Fertilizer utilization efficiency and crop yield test Experimental purpose: To test the difference in fertilizer utilization efficiency and crop yield between Example 3 (composite slow-release granular fertilizer containing chitosan coating) and Comparative Example 3 (granular fertilizer without chitosan coating) in rice cultivation, and to evaluate the regulatory effect of chitosan coating.

[0102] Experimental description: Experimental steps: Experimental material preparation: Example 3 Composite slow-release granular fertilizer (chitosan coating).

[0103] Comparative Example 3: Composite granular fertilizer (without chitosan coating).

[0104] Blank control group: no fertilizer, only substrate soil as the basis.

[0105] Planting design: Crop: Rice.

[0106] Soil type: Acidic soil, containing about 1.5% organic matter and a pH of 5.8.

[0107] Experimental field area: 5 mu randomized block design for each treatment, with 3 replications.

[0108] Fertilization plan: Base fertilizer: Apply 80 kg of granular fertilizer per mu, before sowing and after tillage; Top dressing: Apply 40 kg of granular fertilizer per mu in the form of strip application during the tillering stage (about 30 days later) with a depth of 8 cm.

[0109] Crop Management: After sowing, follow standard field management, regular irrigation, pest and disease control, and maintain uniform moisture conditions (soil moisture 50%-60%).

[0110] Test indicators: Crop yield: After harvest, every 5 mu of crops were harvested uniformly and the yield per unit area (kg / mu) was measured.

[0111] Fertilizer utilization rate: calculated by the absorption of nitrogen, phosphorus and potassium by the aboveground parts of crops and the total amount applied.

[0112] Test period: 120 days, from sowing to harvesting.

[0113] Experimental data: Experimental data on fertilizer utilization efficiency and crop yield comparison Experimental summary: In the data, Example 3 showed a higher fertilizer utilization rate throughout the growth cycle, especially in nitrogen absorption. Chitosan effectively slowed down the loss of nitrogen through its slow release and protection functions. In contrast, in Comparative Example 3, there was no coating protection, the initial fertilizer release rate was too high, and the later supply was insufficient, resulting in nutrient waste and decreased utilization efficiency. The blank control was more illustrative, as the crop lacked sufficient fertilizer supply and the absorption was significantly low.

[0114] The yield per unit area of ​​rice treated in Example 3 is significantly better than that in Comparative Example 3, which is due to the matching of nutrient release and crop demand. The chitosan protective layer combines slow release with biological activity, which not only regulates the fertilizer release process, but also enhances the absorption capacity of the root system. This hierarchical design just solves the technical problem of nutrient supply interruption of ordinary fertilizers in the late growth period, while the design of comparative example 3 lacks a protective layer, which seems to lack stamina.

[0115] The absorption of potassium can also reflect the rationality of fertilization treatment. The chitosan protective layer in Example 3 plays a key role in the homeostasis of potassium ions in the soil. In Comparative Example 3, due to the lack of coating protection, excessive potassium release in the early stage leads to insufficient potassium release in the later stage. The design of Example 3 not only improves the efficiency of fertilizer utilization by gradually releasing potassium ions, but also maintains the subsequent driving force for healthy growth of crops. Combined with the regulation mechanism of fertilizers, this layer-by-layer slow-release strategy is more in line with the rhythm of nutrient demand in actual planting.

[0116] Experiment 4: Soil organic matter and microbial activity test Experimental purpose: to test the effects of Example 4 (layered granulated composite granular fertilizer) and Comparative Example 4 (single-layer granulated granular fertilizer) on soil organic matter content and microbial activity, and to verify the effect of the present invention in improving the soil ecological environment.

[0117] Experimental description: Experimental steps: Experimental material preparation: Example 4 Composite granular fertilizer (layered granulation design).

[0118] Comparative Example 4 Granular fertilizer (single-layer granulation design).

[0119] Blank control group: no fertilizer was applied, only poor soil (organic matter content <1%) was used.

[0120] Soil treatment: Poor sandy soil was selected, air-dried and then passed through a 2 mm sieve. 8 kg of soil was placed in each experimental container, using a container with a diameter of 25 cm and a height of 40 cm.

[0121] Three replicates were set up for each group, with a total of 9 treatment containers.

[0122] Fertilization plan: The fertilizers of Example 4 and Comparative Example 4 were applied at a rate of 90 kg per mu, and after being spread in equal amounts, they were lightly raked and mixed, and covered with 3 cm of thin soil. The blank group was not fertilized, and the soil was only kept moist.

[0123] Experimental setup: Simulate the natural rainfall environment, maintain the soil moisture content at 40%-50%, and replenish water every 5 days.

[0124] Grow at room temperature away from direct light and extreme temperatures.

[0125] Sampling and testing: Every 30 days, samples were taken from the soil surface at 0-10 cm to test the organic matter content and soil microbial respiration rate.

[0126] Testing period: 120 days, with 5 samplings in total.

[0127] Detection method: Organic matter content: Determined by potassium dichromate oxidation method.

[0128] Microbial activity: Determined by soil respiration rate method (microbial activity is measured by CO2 release).

[0129] Experimental data: Comparative experimental data of soil organic matter and microbial activity Experimental summary: The design of layered granulation not only has a direct impact on nutrient release, but also indirectly promotes the improvement of soil ecological environment. From the experimental data, the soil organic matter content of Example 4 increased significantly over time, which was significantly higher than that of Comparative Example 4 and the blank control group. This effect mainly comes from the synergistic effect of organic fertilizers and natural minerals in the layered design. The quick release of organic fertilizers in the core layer provides the soil with an initial nutrient basis, while the slow-release mechanism of the middle and outer layers continues to supplement organic matter for the soil. In contrast, the single-layer granulation method of Comparative Example 4 failed to maintain this balance, with too fast release in the early stage and gradual decline in the later stage.

[0130] The comparison of microbial activity is also clear. In Example 4, the soil respiration rate gradually increased over time, showing that the soil microorganisms were more active. This phenomenon can be attributed to the introduction of humic acid and chitosan, which not only provide additional active matrix for microorganisms, but also improve the soil aggregate structure and create an environment more suitable for microbial survival. However, due to the lack of stratification regulation in Comparative Example 4, the organic matter released in the early stage is difficult to maintain the long-term activity of microorganisms, and the respiration rate in the later stage decreases significantly.

[0131] The data of the blank group showed that unfertilized barren soil could not effectively improve ecological functions. In the long run, the change of organic matter in the blank group soil was close to the background value, and the microbial activity was always at a low level. This further highlights the advantages of combining minerals and organic fertilizers in compound fertilizers, especially the precise control of the release process after stratification and granulation, which not only solves the problem of crop nutrient supply, but also achieves deep restoration of soil structure and ecological environment.

[0132] Experiment 5: Nutrient loss test under rainy season conditions Experimental purpose: To verify the ability of Example 5 (fine-sized mineral particles) and Comparative Example 5 (large-sized mineral particles) to control the loss of nitrogen, phosphorus and potassium nutrients under rainy season conditions, and to evaluate the effect of particle size differences on fertilizer performance.

[0133] Experimental description: Experimental steps: Experimental material preparation: Example 5 Composite slow-release granular fertilizer (fine-particle minerals, particle size 0.2-0.4 mm).

[0134] Comparative Example 5: composite granular fertilizer (large-size mineral particles, particle size 0.5-0.8 mm).

[0135] Soil and container setup: Use sandy soil (easy to leach) with a pH value of 6.5 and an organic matter content of 1.2%.

[0136] Soil column device: PVC pipes with a height of 50 cm and a diameter of 30 cm, each pipe was filled with 10 kg of soil.

[0137] Three replicates were set up in each group, with a total of 6 soil columns.

[0138] Fertilization treatment: Apply granular fertilizer at the rate of 100 kg per mu and spread evenly on the soil surface.

[0139] Simulate rainy season conditions, artificial irrigation, simulate rainfall of 30mm / h each time, duration of 2 hours, rainfall every 7 days, and simulate 7 times in succession.

[0140] Experimental setup: After each rainfall, the permeate from the bottom of the soil column was collected to determine the nitrogen, phosphorus and potassium content.

[0141] Indoor experiments were conducted with the temperature maintained at 25°C and external precipitation interference avoided.

[0142] Detection method: Nitrogen content: Kjeldahl method.

[0143] Phosphorus content: molybdenum blue colorimetric method.

[0144] Potassium content: flame photometry.

[0145] Data Records: The nutrient content in the permeate was recorded after each rainfall, and the cumulative loss was analyzed.

[0146] Experimental data: Comparative experimental data of nutrient loss under rainy season conditions Experimental summary: It can be seen from the above experiments that fine-particle minerals obviously play a better role in controlled release under rainy season conditions. The loss of nitrogen, phosphorus and potassium in Example 5 is significantly lower than that in Comparative Example 5 after each simulated rainfall. This is mainly due to the larger specific surface area and stronger adsorption capacity of fine-particle minerals, which can significantly reduce the release rate of nutrients. Large-particle minerals have a small surface area and release faster in the initial stage, resulting in more serious nutrient loss in the first few rainfalls, making it more difficult to maintain a stable supply in the long run.

[0147] In Comparative Example 5, due to the rough surface of large-particle minerals, phosphate was quickly released into soil water after dissolution, causing the phosphorus content to gradually accumulate in the rainfall infiltration liquid. In Example 5, the acid-activated phosphate rock and humic acid formed an organic-inorganic complex. This combination mode not only delayed the release of phosphorus, but also reduced the migration ability of phosphorus, showing a significant phosphorus control effect. Especially in the last few rainfalls, the phosphorus loss of Example 5 was almost maintained at a low level, showing a more stable release characteristic.

[0148] The outer chitosan in Example 5 not only improves the mechanical strength of the particles, but also hinders the penetration of water to a certain extent, so that the release process of potassium ions is effectively delayed. However, due to the design of no protective layer in Comparative Example 5, potassium ions are released in large quantities in the early stage, and the supply in the later stage is difficult to maintain. This comparison fully illustrates the importance of the protective layer in the layered granulation design, which obviously improves the anti-leaching ability of the fertilizer and provides a guarantee for the balanced supply of nutrients in the soil.

[0149] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for organic agricultural nutrient management combining natural minerals and organic fertilizers, characterized in that: The following steps are involved: S1. Pretreatment of natural minerals, including crushing of zeolite, bentonite and phosphate rock powder, and activation of phosphate rock powder; S2. Pretreatment of organic fertilizers, including mixed fermentation of livestock manure compost and green manure powder; S3. Preparation of composite particles, comprising: Using pre-treated organic fertilizer as the core layer, granules are formed; The core particles are coated with a mixture of pre-treated phosphate rock powder and bentonite to form an intermediate layer; A mixture of zeolite and chitosan solution is coated outside the middle layer to form a protective layer; S4, drying and cooling the prepared composite particles to obtain a composite slow-release fertilizer; S5. Apply base fertilizer and topdressing fertilizer in stages according to crop needs.

2. The organic agricultural nutrient management method combining natural minerals and organic fertilizers according to claim 1, characterized in that: The pretreatment of natural minerals in step S1 includes: S1.1, crush zeolite, bentonite and phosphate rock powder into particle sizes of 0.1-0.5 mm respectively; S1.

2. Use a 1%-2% dilute phosphoric acid solution to activate the phosphate rock powder. The activation time is 30-60 minutes and the activation temperature is 25-35°C.

3. The organic agricultural nutrient management method combining natural minerals and organic fertilizers according to claim 1, characterized in that: The pretreatment of the organic fertilizer in step S2 includes: S2.

1. Mix livestock manure and green manure powder in a weight ratio of 8:2-9:1; S2.

2. Fermentation is carried out through high-temperature composting process, the fermentation temperature is 55-65℃, the fermentation time is 10-15d, the moisture content of the compost is maintained at 50%-60% during the fermentation period, and the frequency of turning the compost is once every 2-3d.

4. The organic agricultural nutrient management method combining natural minerals and organic fertilizers according to claim 1, characterized in that: The preparation of the composite particle core layer in step S3 includes: Using fermented organic fertilizer as the basic raw material; Mixing 10%-15% bentonite and 1%-2% chitosan solution by weight; Core particles with a diameter of 1-2 mm were formed by a disc granulator.

5. The organic agricultural nutrient management method combining natural minerals and organic fertilizers according to claim 1, characterized in that: The preparation of the composite particle intermediate layer in step S3 includes: Mix phosphate rock powder and bentonite in a weight ratio of 1:1-2:1; Spray the humic acid solution to combine the mixture with the core particles; The intermediate sustained-release layer with a thickness of 1-2 mm was formed by disk granulation.

6. The organic agricultural nutrient management method combining natural minerals and organic fertilizers according to claim 1, characterized in that: The preparation of the composite particle protective layer in step S3 includes: Evenly spraying the zeolite powder with the chitosan solution to form a mixture; The mixture is coated on the outside of the middle layer to form an outer layer with a thickness of 0.5-1 mm.

7. The organic agricultural nutrient management method combining natural minerals and organic fertilizers according to claim 1, characterized in that: The composite particles in step S4 are dried using a low-temperature drying process, with a drying temperature of 40-50° C. and a drying time of 4-6 hours.

8. The organic agricultural nutrient management method combining natural minerals and organic fertilizers according to claim 1, characterized in that: The method for applying basal fertilizer in step S5 comprises: Apply the composite particles evenly into the soil before sowing, with a fertilization depth of 10-15cm; The application rate is 60-100 kg per mu.

9. The organic agricultural nutrient management method combining natural minerals and organic fertilizers according to claim 1, characterized in that: The method for applying topdressing in step S5 comprises: In the middle of crop growth, use strip or furrow application; Apply the composite particles near the root zone at a depth of 5-10 cm; The application rate is 30-50 kg per mu.

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