Organic fertilizer containing potamogeton crispus and preparation method thereof

Abstract

The invention relates to the field of fertilizers, in particular to a potamogeton crispus-containing organic fertilizer and a preparation method thereof. The potamogeton crispus-containing organic fertilizer is prepared from the following raw materials in parts by mass: 40-60 parts of a potamogeton crispus composition, 15-25 parts of an excrement auxiliary material, 10-15 parts of a conditioner, 5-10 parts of a functional additive, 5-10 parts of a complex microbial inoculant, 15-25 parts of a coating material, 5-8 parts of a trace element supplement, 2-5 parts of a pH regulator and 20-30 parts of deionized water. The finally prepared potamogeton crispus-containing organic fertilizer can keep excellent fertilizer efficiency, the problems of safety, storage performance and use effectiveness of the potamogeton crispus-containing organic fertilizer can be solved, by providing a mature potamogeton crispus-containing organic fertilizer preparation process, the existing fertilizer preparation thought is perfected, and the potamogeton crispus-containing organic fertilizer has a wide application prospect. Therefore, effective utilization of aquatic plant resources is achieved, water pollution is relieved, and the method has very remarkable application value.

Description

Technical Field

[0001] The present application relates to the field of fertilizers, and more specifically to an organic fertilizer containing water chestnuts and a preparation method thereof. Background Art

[0002] Water Chestnut is a perennial submerged plant widely distributed in freshwater lakes, ponds and slow-flowing waters. It has the characteristics of high biomass, rapid growth and strong adaptability. Its plants are rich in mineral elements such as nitrogen (N), phosphorus (P), potassium (K) and organic matter. The crude protein content in dry matter can reach 15%~25%. It also contains a variety of amino acids, vitamins and functional polysaccharides. It is a high-quality natural organic material resource. In recent years, with the intensification of eutrophication of water bodies, the over-reproduction of Water Chestnut in some waters has become a difficult problem for ecological management, but its potential as a raw material for organic fertilizers has gradually attracted attention. Using Water Chestnut to prepare organic fertilizers can not only reduce the waste of aquatic plant resources, but also alleviate water pollution through resource utilization, which has significant ecological and economic value.

[0003] Organic fertilizer is a natural fertilizer made from animal and plant residues or metabolites through microbial fermentation. Its core advantage lies in improving soil structure, enhancing water and fertilizer retention capacity, and promoting soil microbial activity. Traditional organic fertilizer raw materials are mostly livestock and poultry manure, crop straw or food waste, but their nutrient ratio is unbalanced (for example, livestock and poultry manure has a high nitrogen content but insufficient phosphorus and potassium), the fermentation cycle is long, and it is easy to produce odor and pathogen residues, which limits the application effect. At present, the main problems with organic fertilizers containing water caltrops are insufficient raw material processing and problems with their safety, storage and effectiveness caused by formulation issues. For example, water caltrops are not thoroughly decomposed, and the release of effective nutrients (such as nitrogen and phosphorus) does not match the fertilizer requirement cycle of crops, which can easily cause nutrient loss or short-term fertilizer efficiency deficiency. On the other hand, the process compatibility of preparing organic fertilizers containing water caltrops is poor. Existing technologies mostly focus on the fermentation of a single raw material (such as pure livestock and poultry manure or straw), and lack optimization of the coordinated treatment of water caltrops and other organic wastes (such as sludge and fungal residue), resulting in an imbalance in the carbon-nitrogen ratio and poor adaptability of fermentation agents. Summary of the invention

[0004] Therefore, in order to effectively solve the above-mentioned existing problems, the present application provides an organic fertilizer containing Water Chestnut and a preparation method thereof. The organic fertilizer containing Water Chestnut finally prepared by the present application can not only maintain excellent fertilizer efficiency, but also solve the problems of safety, storage and effectiveness of use of organic fertilizer containing Water Chestnut, and by providing a mature preparation process of Water Chestnut organic fertilizer, the existing preparation ideas of this type of fertilizer are improved, thereby realizing the effective utilization of aquatic plant resources and alleviating water pollution, and has very significant application value.

[0005] The organic fertilizer containing water chestnut is composed of the following raw materials, measured by mass: 40-60 parts of water chestnut composition, 15-25 parts of feces auxiliary material, 10-15 parts of conditioner, 5-10 parts of functional additives, 5-10 parts of composite bacterial agent, 15-25 parts of coating material, 5-8 parts of trace element supplementer, 2-5 parts of pH regulator and 20-30 parts of deionized water.

[0006] As a preferred embodiment, the mass ratio of the water chestnut composition, the feces auxiliary material and the conditioner is (45-55): (18-23): (11-13).

[0007] As a preferred embodiment, the mass ratio of the water chestnut composition, the feces auxiliary material and the conditioner is (50-53): (20-22): (12-12.5).

[0008] As a preferred embodiment, the mass ratio of the functional additive and the coating material in the water chestnut composition is (45-55): (7-8): (16-20).

[0009] As a preferred embodiment, the preparation method of the water chestnut composition specifically includes the following steps: S1: soaking the water chestnut in a mixed solution of cellulase and xylanase for enzymatic hydrolysis to break the cell wall; S2: mixing the water chestnut after enzymatic hydrolysis with lactic acid bacteria fermentation liquid, adding sodium sulfide to adsorb heavy metals, and rinsing with a composite solution of citric acid and EDTA-disodium after completion; S3: after the rinsing is completed, the water chestnut is inoculated with Bacillus subtilis for aerobic fermentation to degrade residual organic matter, and then dried and crushed to obtain the product.

[0010] As a preferred embodiment, the preparation method of the water chestnut composition specifically includes the following steps: S1: chop fresh water chestnut into 1-2 cm segments, soak in a mixed solution of cellulase and xylanase, and perform enzymolysis at 43-45°C for 2-3 hours to break the cell walls; S2: mix the water chestnut with lactic acid bacteria fermentation liquid after enzymolysis, add sodium sulfide, and oscillate at 38-40°C for 6-8 hours to adsorb heavy metals, and then rinse with citric acid and EDTA-disodium composite solution 2-3 times after completion; S3: after rinsing, inoculate water chestnut with Bacillus subtilis, and ferment aerobically at 30-32°C for 20-24 hours to degrade residual organic matter, and then dry with hot air at 55-60°C to a moisture content of ≤3%, and crush to 100-200 mesh.

[0011] As a preferred embodiment, the soaking liquid-to-solid ratio in S1 is (4.5-5.5):1.

[0012] As a preferred embodiment, the enzyme activity of the mixed solution of cellulase and xylanase is ≥5000 U / g.

[0013] As a preferred embodiment, in the composite solution of citric acid and EDTA-disodium, the mass concentration of citric acid is 1-3%, and the mass concentration of EDTA-disodium is 0.05-0.1%.

[0014] As a preferred embodiment, the eluent-to-solid ratio in S2 is (2.5-3):1.

[0015] As a preferred embodiment, the inoculation amount of Bacillus subtilis is 0.6-1%.

[0016] As a preferred embodiment, the mass ratio of the water chestnut, cellulase and xylanase is (90-100): (0.5-1): (0.2-0.5).

[0017] As a preferred embodiment, the mass ratio of the water chestnut, lactic acid bacteria fermentation liquid and sodium sulfide is (90-100): (7-9): (0.1-0.3).

[0018] As a preferred embodiment, the manure auxiliary material is a combination of chicken manure and cow manure.

[0019] As a preferred embodiment, the mass ratio of chicken manure to cow manure is (3-5): (1.5-2.5).

[0020] As a preferred embodiment, the conditioning agent is at least one of wheat straw, corn straw, rice straw and soybean straw.

[0021] As a preferred embodiment, the conditioning agent is wheat straw or corn straw.

[0022] As a preferred embodiment, the functional additive is a composition of humic acid and zeolite powder.

[0023] As a preferred embodiment, the mass ratio of humic acid to zeolite powder is (3-5): (2-4).

[0024] As a preferred embodiment, the mass ratio of humic acid to zeolite powder is (4-4.5): (2.5-3).

[0025] As a preferred embodiment, the composite bacterial agent is a combination of cellulose decomposing bacteria, Trichoderma and Bacillus.

[0026] As a preferred embodiment, the mass ratio of the cellulose decomposing bacteria, Trichoderma and Bacillus is (5-6): (2-3): (1.5-2.5).

[0027] As a preferred embodiment, the viable cell count of the cellulose decomposing bacteria is ≥ 2×10 9 CFU / g.

[0028] As a preferred embodiment, the viable count of Trichoderma is ≥ 1×10 9 CFU / g.

[0029] As a preferred embodiment, the viable count of the Bacillus is ≥5×10 9 CFU / g.

[0030] As a preferred embodiment, the coating material is modified polylactic acid.

[0031] As a preferred embodiment, the preparation method of the modified polylactic acid specifically includes the following steps: S1: adding polylactic acid to dimethyl sulfoxide, stirring until completely dissolved, adding citric acid-based polyethylene glycol, tannic acid, ε-polylysine and ammonium persulfate, and heating to react under nitrogen protection; S2: adding genipin after cooling, keeping the temperature for reaction, pouring the product into ethanol for precipitation, filtering and vacuum drying the solid, crushing and sieving to obtain.

[0032] As a preferred embodiment, the preparation method of the modified polylactic acid specifically includes the following steps: S1: adding polylactic acid to dimethyl sulfoxide, stirring at 60-65°C for 2-3h until completely dissolved, adding citric acid-based polyethylene glycol, tannic acid, ε-polylysine and ammonium persulfate, heating to 70-75°C under nitrogen protection, and reacting for 5-6h; S2: adding genipin after cooling to 45-50°C, keeping the temperature for reaction for 3-4h, pouring the product into ethanol for precipitation, filtering and vacuum drying at 60-65°C for 10-12h, and crushing through a 100-200 mesh sieve to obtain.

[0033] As a preferred embodiment, the weight average molecular weight of the polylactic acid is 90,000-110,000 Da.

[0034] As a preferred embodiment, the mass ratio of the polylactic acid, citric acid-based polyethylene glycol, tannic acid and ε-polylysine is (90-100): (15-18): (8-10): (4-6).

[0035] As a preferred embodiment, the mass ratio of the polylactic acid, citric acid-based polyethylene glycol, tannic acid and ε-polylysine is 100:16:8:5.

[0036] By adding modified polylactic acid, it can not only form a physical barrier for the fertilizer particles, delay the release rate of nutrients (N, P, K) to match it with the crop growth cycle, but also accelerate the degradation of the film layer under acidic soil conditions through pH responsiveness through the introduced carboxyl group, and realize intelligent release. The modified polylactic acid can cross-link with the PLA molecular chain through tannic acid through phenolic hydroxyl groups to form a three-dimensional network structure, enhance thermal stability, and at the same time, with the zwitterionic structure of ε-polylysine, the hydrophobicity of the film surface is significantly improved, and the amino group of ε-polylysine is tightly combined with the surface of the fertilizer particles (including humic acid, zeolite, etc.) through hydrogen bonds and electrostatic effects, reducing the shedding of the capsule, thereby ensuring that the organic fertilizer particles have excellent storage stability, moisture and heat resistance, and release tropism with crops while ensuring fertilizer efficiency.

[0037] As a preferred embodiment, the trace element supplement is at least one of EDTA-Fe, EDTA-Zn, EDTA-Mn, ferrous sulfate and zinc sulfate.

[0038] As a preferred embodiment, the trace element supplement is a composition of EDTA-Fe and EDTA-Zn.

[0039] As a preferred embodiment, the mass ratio of EDTA-Fe to EDTA-Zn is (1.5-3): (1-1.5).

[0040] As a preferred embodiment, the pH adjuster is at least one of citric acid, potassium dihydrogen phosphate and calcium hydroxide.

[0041] As a preferred embodiment, the pH adjuster is citric acid.

[0042] The preparation method of organic fertilizer containing water chestnut specifically comprises the following steps: S1: putting water chestnut, feces auxiliary material and regulator into a mixer in proportion, adding functional additives, trace element supplements, pH regulator and deionized water, stirring and mixing evenly, and then adding composite bacterial agent and stirring evenly; S2: aerobic fermentation, temperature 55-65°C, turning frequency once every 40-48 hours, lasting 10-12 days, oxygen concentration ≥15%; anaerobic fermentation, sealed stacking, temperature 40-45°C, lasting 20-25 days until completely decomposed, C / N ≤18 and GI ≥85%, to obtain decomposed material; S3: forming the decomposed material through an extrusion granulator, controlling the average particle size to be 2-4 mm, drying at 80-85°C to a water content of ≤8%, dissolving the coating material in a solvent and spraying it on the surface of the particles, and curing with air blowing at 60-65°C for 3-3.5 hours, and obtaining the product after completion.

[0043] The beneficial effects of this application are: 1. The organic fertilizer containing water chestnut provided in the present application can not only maintain excellent fertilizer efficiency, but also solve the problems of safety, storage and effectiveness of use of organic fertilizers containing water chestnut, and improve the existing preparation ideas of such fertilizers by providing a mature water chestnut organic fertilizer preparation process, thereby realizing the effective utilization of aquatic plant resources and alleviating water pollution, and has very significant application value.

[0044] 2. The organic fertilizer containing water chestnut provided in the present application accelerates the decomposition of cellulose, hemicellulose and lignin through a refined treatment process of water chestnut, and reduces the bioavailability of heavy metals in water chestnut through a combination of adsorption and leaching, while avoiding the negative impact of the salt it contains on the soil. Finally, through secondary treatment with microorganisms, the maturity of organic matter in water chestnut and the durability of fertilizer effect are improved, thereby ensuring the stability of the organic fertilizer itself.

[0045] 3. The present application provides an organic fertilizer containing water chestnuts, which delays the nutrient release rate by adding modified polylactic acid to match the crop growth cycle, and can also accelerate the degradation of the film layer under acidic soil conditions through pH responsiveness through the introduced carboxyl group to achieve intelligent release. The modified polylactic acid can be cross-linked with the PLA molecular chain through tannic acid through phenolic hydroxyl groups to form a three-dimensional network structure, and the amino group of ε-polylysine is tightly combined with the surface of the fertilizer particles (including humic acid, zeolite, etc.) through hydrogen bonds and electrostatic effects, reducing the shedding of the capsule, thereby ensuring that the organic fertilizer particles have excellent storage stability, moisture and heat resistance, and release tropism with crops while ensuring the fertilizer effect. DETAILED DESCRIPTION

[0046] In the specific implementation manner, specific implementation cases will be used to more intuitively display and illustrate the contents of the invention content of this application.

[0047] Example 1: The organic fertilizer containing Water Chestnut is composed of the following raw materials, calculated by mass: 52.4 parts of Water Chestnut composition, 21.1 parts of feces auxiliary material, 12 parts of conditioner, 7.8 parts of functional additive, 6.2 parts of composite bacterial agent, 18.5 parts of coating material, 6.2 parts of trace element supplement, 3.3 parts of pH adjuster, and 28.5 parts of deionized water.

[0048] The preparation method of the water chestnut composition, by weight, specifically comprises the following steps: S1: chopping 100 parts of fresh water chestnuts into 1.5 cm segments, soaking in a mixed solution containing 0.8 parts of cellulase and 0.4 parts of xylanase (enzyme activity ≥ 5000U / g) (the soaking liquid-solid ratio is 5:1), enzymolysis at 45°C for 3h to break the cell wall; S2: mixing the enzymolysis water chestnuts with 8.5 parts of lactic acid bacteria fermentation liquid, adding 0.22 parts of sodium sulfide, shaking and reacting at 40°C The mixture was incubated for 7 hours to adsorb heavy metals, and then rinsed with a composite solution of citric acid and EDTA-disodium (the mass concentration of citric acid is 2%, and the mass concentration of EDTA-disodium is 0.08%) for 3 times (the solid ratio of the elution liquid is 3:1). S3: After elution, the water chestnuts were inoculated with Bacillus subtilis (inoculation amount is 1%) and aerobically fermented at 30℃ for 24 hours to degrade residual organic matter. After completion, they were dried with hot air at 60℃ to a moisture content of ≤3%, and crushed to 150 mesh.

[0049] The lactic acid bacteria fermentation broth was purchased from the corresponding agricultural-grade products sold by China Yukang (Shandong) Biotechnology Co., Ltd.

[0050] The manure auxiliary material is a combination of chicken manure and cow dung with a mass ratio of 4.5:1.5. Both chicken manure and cow dung were purchased from Shandong Minhe Biological Co., Ltd., China; the conditioning agent is wheat straw, which was purchased from Henan Jingu Co., Ltd., China.

[0051] The functional additive is a composition of humic acid and zeolite powder, with a mass ratio of 4.5:3.

[0052] Humic acid was purchased from the mineral-source humic acid products sold by Shanxi Meibang Co., Ltd. in China.

[0053] The composite bacterial agent is a combination of cellulose decomposing bacteria, Trichoderma and Bacillus, with a mass ratio of 5.5:2:1.5.

[0054] The viable count of cellulose decomposing bacteria was 2.8×10 9 CFU / g, purchased from Shandong Lvlong Co., Ltd., China.

[0055] The viable count of Trichoderma was 1.4×10 9 CFU / g, purchased from Trichoderma harzianum sold by Wuhan Kono Co., Ltd., China.

[0056] The number of viable Bacillus was 6.5×10 9 CFU / g, Bacillus subtilis purchased from Zhongnong Weite Co., Ltd., China.

[0057] The coating material is modified polylactic acid, and its preparation method specifically includes the following steps, calculated by mass: S1: adding 100 parts of polylactic acid to 300 parts of dimethyl sulfoxide, stirring at 65°C for 3 hours until completely dissolved, adding 16 parts of citric acid-based polyethylene glycol, 8 parts of tannic acid and 5 parts of ε-polylysine and 0.5 parts of ammonium persulfate, heating to 75°C under nitrogen protection, and reacting for 6 hours; S2: after cooling to 50°C, adding 1 part of genipin, keeping the temperature for reaction for 3 hours, pouring the product into ethanol for precipitation, filtering and vacuum drying at 65°C for 12 hours, crushing and passing through a 150-mesh sieve to obtain the product.

[0058] The weight average molecular weight of polylactic acid was 100,000 Da, and it was purchased from Hubei Xinyuhong Biopharmaceutical Technology Co., Ltd., China.

[0059] Genipin purchased CP-grade products sold by Wuhan Lanabai Pharmaceutical Chemical Co., Ltd. in China.

[0060] The trace element supplement is a composition of EDTA-Fe and EDTA-Zn with a mass ratio of 2.5:1.5.

[0061] The pH adjuster was citric acid.

[0062] The preparation method of organic fertilizer containing water chestnut includes the following steps: S1: putting water chestnut, feces auxiliary material and regulator into a mixer in proportion, adding functional additives, trace element supplements, pH regulator and deionized water, stirring and mixing evenly, and then adding composite bacterial agent and stirring evenly; S2: aerobic fermentation, temperature 60°C, turning frequency once every 48 hours, lasting 11 days, oxygen concentration ≥15%; anaerobic fermentation, sealed stacking, temperature 45°C, lasting 24 days until completely decomposed, C / N ≤18 and GI ≥85%, to obtain decomposed material; S3: forming the decomposed material through an extrusion granulator, controlling the average particle size to 3mm, drying at 85°C to a water content of ≤8%, dissolving the coating material in ethanol and spraying it on the surface of the particles, and curing at 60°C with air blowing for 3h, and obtaining the product after completion.

[0063] Example 2: This example differs from Example 1 only in the following: the organic fertilizer containing Water Chestnut, in which the raw materials consist of the following components, by mass: 48.5 parts of Water Chestnut composition, 19.5 parts of feces auxiliary material, 11 parts of conditioner, 7.2 parts of functional additive, 6.2 parts of composite bacterial agent, 16.2 parts of coating material, 6.1 parts of trace element supplement, 2.8 parts of pH adjuster, and 26.5 parts of deionized water.

[0064] Example 3: This example differs from Example 1 only in the following: the organic fertilizer containing Water Chestnut, in which the raw materials consist of the following components, by mass: 55 parts of Water Chestnut composition, 18 parts of feces auxiliary material, 13 parts of conditioner, 8 parts of functional additive, 6.2 parts of composite bacterial agent, 19.5 parts of coating material, 6.2 parts of trace element supplement, 3.3 parts of pH adjuster, and 25.5 parts of deionized water.

[0065] The functional additive is a combination of humic acid and zeolite powder with a mass ratio of 5:2.

[0066] Comparative Example 1 The only difference between this comparative example and Example 1 is as follows: the organic fertilizer containing Water Chestnut is composed of the following ingredients, measured by mass: 68.5 parts of Water Chestnut composition, 25.5 parts of feces auxiliary material, 12 parts of conditioner, 7.8 parts of functional additive, 6.2 parts of composite bacterial agent, 8.5 parts of coating material, 6.2 parts of trace element supplement, 3.3 parts of pH adjuster, and 28.5 parts of deionized water.

[0067] Comparative Example 2 The only difference between this comparative example and Example 1 is that the composite bacterial agent is a cellulose decomposing bacteria, a combination of Trichoderma and Bacillus, with a mass ratio of 9:1:0.2.

[0068] Comparative Example 3 The only difference between this comparative example and Example 1 is that the functional additive is a composition of humic acid and zeolite powder, and the mass ratio is 1:3.

[0069] Comparative Example 4 The only difference between this comparative example and Example 1 is as follows: the preparation method of the water chestnut composition, calculated by mass, specifically comprises the following steps: S1: chop 100 parts of fresh water chestnut into 1.5 cm segments, soak in a mixed solution containing 0.8 parts of cellulase and 0.4 parts of xylanase (enzyme activity ≥5000U / g) (the soaking liquid-solid ratio is 5:1), and enzymolyze at 45°C for 3 hours to break the cell walls; S2: after enzymolysis, the water chestnut is rinsed with a composite solution of citric acid and EDTA-disodium (the mass concentration of citric acid is 2%, and the mass concentration of EDTA-disodium is 0.08%) for 3 times (the leaching liquid-solid ratio is 3:1); S3: after leaching, the water chestnut is inoculated with Bacillus subtilis (inoculation amount is 1%), and aerobically fermented at 30°C for 24 hours to degrade residual organic matter. After completion, it is hot-air dried at 60°C to a moisture content of ≤3%, and crushed to 150 mesh.

[0070] Comparative Example 5 The only difference between this comparative example and Example 1 is as follows: the coating material is modified polylactic acid, and its preparation method specifically includes the following steps, calculated by mass: S1: adding 100 parts of polylactic acid to 300 parts of dimethyl sulfoxide, stirring at 65°C for 3 hours until completely dissolved, adding 25 parts of citric acid-based polyethylene glycol, 5 parts of tannic acid and 1 part of ε-polylysine and 0.5 parts of ammonium persulfate, heating to 75°C under nitrogen protection, and reacting for 6 hours; S2: after cooling to 50°C, adding 1 part of genipin, keeping the temperature for reaction for 3 hours, pouring the product into ethanol for precipitation, filtering and vacuum drying at 65°C for 12 hours, crushing and passing through a 150-mesh sieve to obtain.

[0071] Comparative Example 6 The only difference between this comparative example and Example 1 is as follows: the coating material is modified polylactic acid, and its preparation method specifically includes the following steps, calculated by mass: S1: adding 100 parts of polylactic acid to 300 parts of dimethyl sulfoxide, stirring at 65°C for 3 hours until completely dissolved, adding 4 parts of citric acid-based polyethylene glycol, 12 parts of tannic acid and 2 parts of ε-polylysine and 0.5 parts of ammonium persulfate, heating to 75°C under nitrogen protection, and reacting for 6 hours; S2: after cooling to 50°C, adding 1 part of genipin, keeping the temperature for reaction for 3 hours, pouring the product into ethanol for precipitation, filtering and vacuum drying at 65°C for 12 hours, crushing and passing through a 150-mesh sieve to obtain.

[0072] Performance Evaluation 1. The organic fertilizer containing water chestnut prepared in the embodiment and the comparative example was mixed with soil in a mass ratio of 1:10, stirred and evenly loaded into a plexiglass column with a diameter of 10 cm and a height of 50 cm; simulated rainfall (distilled water, pH=6.5, 100 mL / time) was used for leaching every week, and the leaching solution was collected; the concentrations of NH4⁺-N and NO3⁻-N in the leaching solution were determined by a continuous flow analyzer, and the cumulative nitrogen comprehensive release rate was calculated. The test period was 180 days (sampling was performed at 30 days, 90 days, and 180 days), and the nitrogen release rate results for 180 days were recorded in Table 1.

[0073] 2. The organic fertilizer containing Potamogeton crispus prepared in the embodiment and the comparative example was placed in a constant temperature oven (40±1°C, simulating a high temperature storage environment) for 30 days, and samples were taken every 10 days to determine the total nitrogen retention rate. The total nitrogen retention rate after the final 30 days was recorded in Table 1.

[0074] 3. The organic fertilizer containing water chestnut prepared in the embodiment and the comparative example was placed in a constant temperature and humidity chamber (25°C, RH=80%). After 48 hours, it was taken out and weighed until the mass was constant. The moisture absorption rate was calculated: moisture absorption rate (%) = (Wt-W0) / W0×100%, where W0 is the initial dry weight and Wt is the weight after moisture absorption. The results were averaged from 10 tests and recorded in Table 1.

[0075] Table 1 Performance evaluation table

[0076] From the final performance test results of the embodiments and comparative examples, comparative examples 1 to 6 achieved worse performance results than the embodiments, while the embodiments, by adopting a better technical solution, obtained modified polylactic acid to delay the nutrient release rate so that it matches the crop growth cycle, and can also accelerate the degradation of the film layer under acidic soil conditions through pH responsiveness through the introduced carboxyl group to achieve intelligent release. The modified polylactic acid can be cross-linked with the PLA molecular chain through tannic acid through phenolic hydroxyl groups to form a three-dimensional network structure, and the amino group of ε-polylysine is tightly combined with the surface of the fertilizer particles (including humic acid, zeolite, etc.) through hydrogen bonds and electrostatic effects, reducing the shedding of the capsule, thereby ensuring that the organic fertilizer particles have excellent storage stability, moisture and heat resistance, and release tropism with crops while ensuring the fertilizer effect.

Claims

1. An organic fertilizer containing Potamogeton crispus, characterized in that: The raw materials are composed of the following components by mass: 40-60 parts of water chestnut composition, 15-25 parts of feces auxiliary material, 10-15 parts of conditioner, 5-10 parts of functional additive, 5-10 parts of composite bacterial agent, 15-25 parts of coating material, 5-8 parts of trace element supplement, 2-5 parts of pH regulator, and 20-30 parts of deionized water; The preparation method of the water chestnut composition specifically comprises the following steps: S1: soaking the water chestnut in a mixture of cellulase and xylanase for enzymatic hydrolysis to break the cell wall; S2: mixing the water chestnut with lactic acid bacteria fermentation liquid after enzymatic hydrolysis, adding sodium sulfide to absorb heavy metals, and rinsing with a citric acid and EDTA-disodium composite solution after completion; S3: after rinsing, inoculating Bacillus subtilis with the water chestnut for aerobic fermentation to degrade residual organic matter, and drying and crushing to obtain the product; The inoculation amount of Bacillus subtilis is 0.6-1%; The mass ratio of the water chestnut, cellulase and xylanase is (90-100): (0.5-1): (0.2-0.5); The mass ratio of the water chestnut, lactic acid bacteria fermentation liquid and sodium sulfide is (90-100): (7-9): (0.1-0.3).

2. The organic fertilizer containing Potamogeton crispus according to claim 1, characterized in that: The mass ratio of the water chestnut composition, the feces auxiliary material and the conditioner is (45-55): (18-23): (11-13).

3. The organic fertilizer containing Potamogeton crispus according to claim 2, characterized in that: The manure auxiliary material is a combination of chicken manure and cow manure, with a mass ratio of (3-5): (1.5-2.5).

4. The organic fertilizer containing Potamogeton crispus according to claim 3, characterized in that: The conditioning agent is at least one of wheat straw, corn straw, rice straw and soybean straw.

5. The organic fertilizer containing Potamogeton crispus according to claim 4, characterized in that: The functional additive is a composition of humic acid and zeolite powder, with a mass ratio of (3-5): (2-4).

6. The organic fertilizer containing Potamogeton crispus according to claim 5, characterized in that: The composite bacterial agent is a combination of cellulose decomposing bacteria, Trichoderma and Bacillus, with a mass ratio of (5-6): (2-3): (1.5-2.5).

7. The organic fertilizer containing Potamogeton crispus according to claim 6, characterized in that: The coating material is modified polylactic acid, and the preparation method specifically includes the following steps: S1: adding polylactic acid into dimethyl sulfoxide, stirring until completely dissolved, adding citric acid-based polyethylene glycol, tannic acid, ε-polylysine and ammonium persulfate, and heating to react under nitrogen protection; S2: adding genipin after cooling, keeping the temperature for reaction, pouring the product into ethanol for precipitation, filtering and vacuum drying the solid, crushing and sieving to obtain the product.

8. The organic fertilizer containing Potamogeton crispus according to claim 7, characterized in that: The weight average molecular weight of the polylactic acid is 90,000-110,000 Da; the mass ratio of the polylactic acid, citric acid-based polyethylene glycol, tannic acid and ε-polylysine is (90-100): (15-18): (8-10): (4-6).

9. The organic fertilizer containing Potamogeton crispus according to claim 8, characterized in that: The trace element supplement is at least one of EDTA-Fe, EDTA-Zn, EDTA-Mn, ferrous sulfate and zinc sulfate.

10. A method for preparing the organic fertilizer containing Potamogeton crispus according to any one of claims 1 to 9, characterized in that: The specific steps include: S1: Put water chestnut, feces auxiliary materials and regulators into a mixer in proportion, add functional additives, trace element supplements, pH regulator and deionized water, stir and mix evenly, then add composite bacteria agent and stir evenly; S2: Aerobic fermentation, temperature 55~65℃, turning frequency once every 40~48h, lasting 10~12days, oxygen concentration ≥15%; anaerobic fermentation, sealed stacking, temperature 40~45℃, lasting 20~25 days until fully decomposed, C / N≤18 and GI≥85%, to obtain decomposed materials; S3: The decomposed materials are formed by an extrusion granulator, the average particle size is controlled to be 2~4mm, and dried at 80~85℃ to a moisture content of ≤8%, the coating material is dissolved in a solvent and sprayed on the surface of the particles, and air-cured at 60~65℃ for 3~3.5h, and the material is obtained after completion.

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