Novel composite bacteriostatic fertilizer for crops and preparation method thereof

Abstract

The application discloses a novel slow-release crop bacteriostatic composite fertilizer and a preparation method thereof, and belongs to the technical field of slow-release fertilizer. The fertilizer is prepared from thifluzamide 0.5-1 parts, nano slow-release agent 20-30 parts, nitrogen-phosphorus-potassium compound fertilizer 40-50 parts, dispersing agent 0.1-0.3 parts, walnut green peel extract 10-15 parts, humic acid 20-30 parts, mature poultry manure 40-60 parts, polyether modified organic silicon 3-5 parts, sodium carboxymethyl cellulose 5-8 parts and water 10-20 parts; the dispersing agent is composed of polyethylene glycol octyl phenyl ether and cocamidopropyl betaine at a mass ratio of 2:1. The slow-release bacteriostatic composite fertilizer can inhibit the growth of various pathogenic bacteria, realizes the organic combination of long-acting and quick-acting bacteriostatic effects, has excellent bactericidal effect, has good prevention and treatment effect on rice sheath blight, and also provides rich nutrients for crops and promotes the growth and development of crops.

Description

Technical Field

[0001] The present invention belongs to the technical field of slow-release fertilizers, and specifically relates to a novel slow-release compound fertilizer for crop antibacterial use and a preparation method thereof, which is suitable for disease prevention and control and coordinated nutrition supply of field crops, vegetables and cash crops. Background Art

[0002] Plant pathogenic fungi severely impact crop growth and yield, becoming a major bottleneck to sustainable agricultural development. Pesticides play a vital role in combating biological disasters, ensuring crop yields, and promoting sustained and stable growth in agricultural production. However, due to runoff, spray drift, and evaporation or volatilization during field application, the effective utilization rate of pesticides is less than 1%. This inefficient use of pesticides leads to a range of problems, including ecological pollution, eutrophication, and soil degradation. With the development of sustainable agriculture, ecological and environmental protection, food safety, and other issues have become hot topics of concern.

[0003] Fertilizers are agricultural chemical products that combine the functions of pesticides and fertilizers, designed to simultaneously supply nutrients and control pests and diseases. Mixing fertilizers and pesticides to create slow-release fertilizers not only consolidates field operations but also controls the release rate, preventing economic losses from fertilizer loss and water, soil, and air pollution. However, existing slow-release fertilizers often suffer from: 1) relatively high material costs, limited drug loading and encapsulation efficiency, and complex drug delivery methods in some controlled-release systems. This, combined with the complex and volatile external environment, severely impacts the slow-release effect, leading to fertilizer loss and waste; 2) poor matching between the drug release profile and the pathogen infection cycle, resulting in insufficient effective concentrations during critical periods; 3) a single chemical component can easily lead to rapid mutations in pathogens, resulting in a gradual decline in control efficacy; and 4) poor compatibility between the fertilizer carrier and the drug, resulting in interfacial reactions that reduce the stability of the active ingredient. Therefore, a new slow-release and controlled-release compound fertilizer for crop inhibition with effective efficacy against common soil-borne diseases is urgently needed. Summary of the Invention

[0004] The purpose of the present invention is to provide a novel slow-release compound fertilizer for crop antibacterial treatment, which uses a biochar-nanohydroxyapatite composite nanomaterial as a slow-release drug carrier. The nano slow-release agent has a high specific surface area and can adsorb a large amount of thiophanate-methyl and fertilizer nutrients, and realizes the slow release of nutrients and antibacterial components through ion exchange and diffusion mechanisms, thereby reducing the risk of sudden release. At the same time, the added walnut peel extract contains multiple antibacterial active ingredients, which can quickly inhibit the growth of multiple pathogens, realize the organic combination of long-term and fast-acting antibacterial effects, have excellent bactericidal effects, have good prevention and control effects on rice sheath blight, and also provide rich nutrients for crops, thereby promoting the growth and development of crops.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0006] A novel slow-release controlled-release compound fertilizer for crop antibacterial properties is prepared from the following raw materials in parts by weight: 0.5-1 parts of thiofuran, 20-30 parts of a nano slow-release agent, 40-50 parts of a nitrogen, phosphorus and potassium compound fertilizer, 0.1-0.3 parts of a dispersant, 10-15 parts of a walnut peel extract, 20-30 parts of humic acid, 40-60 parts of decomposed poultry and livestock manure, 3-5 parts of polyether-modified silicone, 5-8 parts of sodium carboxymethyl cellulose, and 10-20 parts of water; the dispersant is composed of polyethylene glycol octylphenyl ether and cocamidopropyl betaine in a mass ratio of 2:1.

[0007] Preferably, the nano sustained-release agent is prepared by the following method:

[0008] A. Take wheat straw biochar and immerse it in sodium hydroxide solution for alkaline treatment to obtain alkaline biochar;

[0009] B. Prepare Ca(NO3)2·4H2O into a Ca(NO3)2 solution, then add ammonia water to adjust the pH of the solution to 10.5, then add an equal volume of ammonium dihydrogen phosphate solution, stir at room temperature for 2 hours, heat to 40°C and continue to stand for 12-16 hours, filter and wash alternately with deionized water and ethanol for more than 3 times, and dry in an oven to obtain nanohydroxyapatite;

[0010] C. Weigh 0.5 g of the nanohydroxyapatite obtained in step B, add it to 50 ml of deionized water, and ultrasonically disperse it for 30 minutes to obtain a nanohydroxyapatite suspension;

[0011] D. Soak the alkaline biochar obtained in step A in the nanohydroxyapatite suspension obtained in step C, stir magnetically at 25° C. for 45-60 minutes, filter and wash to neutrality, dry in an oven, and grind through a 200-mesh sieve to obtain the product biochar-nanohydroxyapatite composite nanomaterial.

[0012] Preferably, the specific alkaline treatment method of step A is: immersing 20g of wheat straw biochar in 100ml of 2mol / L sodium hydroxide solution, stirring at 45°C for 2-3h, filtering and washing to neutrality, and then drying to obtain alkaline biochar.

[0013] Preferably, in step B, the concentration of the Ca(NO3)2 solution is 0.5 mol / L, and the concentration of the ammonium dihydrogen phosphate solution is 0.5 mol / L.

[0014] Preferably, the ratio of the alkaline biochar to the nano-hydroxyapatite suspension in step D is 1 g:50 ml.

[0015] Preferably, the walnut green peel extract is prepared by the following method:

[0016] (1) Washing fresh walnut green peel, vacuum drying at 40° C. to a moisture content of ≤8%, freezing with liquid nitrogen, and then pulverizing to a particle size of ≤50 μm to obtain walnut green peel powder;

[0017] (2) The walnut peel powder was mixed with the solvent at a solid-liquid ratio of 1 g:10 ml, and ultrasonic treatment was performed at a power of 300 W and 28 kHz for 5 min. After the ultrasonic treatment, the pH of the mixture was adjusted to 5.0, and a complex enzyme was added thereto. The mixture was hydrolyzed at 45 ° C for 2 h, the enzyme was inactivated, and the mixture was centrifuged. The supernatant was vacuum freeze-dried to obtain powder.

[0018] Preferably, the complex enzyme is composed of cellulase and laccase in a mass ratio of 2:1; the enzyme activity of the laccase is 100,000 u / g, and the enzyme activity of the cellulase is 20,000 u / g.

[0019] Preferably, the solvent is composed of a choline chloride-lactic acid deep eutectic solvent and deionized water in a volume ratio of 3:7; the molar ratio of choline chloride to lactic acid in the choline chloride-lactic acid deep eutectic solvent is 1:2.

[0020] Preferably, the preparation method of the polyether-modified silicone is as follows:

[0021] Step 1: 40 ml of polyetheramine and 36.5 g of 1,1,3,3-tetramethyl-1,3-bis-[3-(oxiranylmethoxy)propyl]disiloxane were placed in a reactor, 200 ml of isopropanol was added as a solvent, the temperature was raised to 100° C., and the reaction was carried out for 3 to 6 hours until the system became clear, thereby obtaining intermediate product A;

[0022] Step 2: Cool the intermediate product A to room temperature, add 4 g of tetramethylammonium hydroxide, stir evenly and raise the temperature to 100°C. After reacting for 30 minutes, add 99.5 g of octamethylcyclotetrasiloxane and 25 g of 3-(trimethoxysilyl)propyldimethyloctadecylammonium chloride, stir and mix evenly and continue to react for 2 hours. Then, vacuum the system to remove small molecular impurities, and continue to react at 100°C until the viscosity of the system no longer changes. The product obtained is polyether-modified silicone.

[0023] The nitrogen, phosphorus and potassium compound fertilizer used in the present invention is a universal compound fertilizer (N-P2O5-K2O: 15-15-15).

[0024] The present invention also provides a method for preparing the novel slow-release controlled-release compound fertilizer for crop antibacterial properties, which comprises the following steps:

[0025] 1) preparing walnut green peel extract;

[0026] 2) preparing nano sustained-release agents;

[0027] 3) Thifluzamide and the dispersant were mixed uniformly, then added to the nano sustained-release agent, stirred and mixed at room temperature for 30 minutes, allowed to stand for 4 hours, and then vacuum freeze-dried to obtain premix A;

[0028] 4) Premix A, walnut peel extract, nitrogen, phosphorus and potassium compound fertilizer, humic acid, and decomposed livestock manure are ground separately and passed through a 60-mesh sieve, mixed evenly according to proportion, and then wet granulated to obtain fertilizer granules;

[0029] 5) The polyether-modified organic silicon, sodium carboxymethyl cellulose and water are mixed evenly to obtain a uniform coating liquid, which is evenly sprayed onto the surface of the medicated fertilizer particles obtained in step 4), and then dried.

[0030] The novel slow-release compound fertilizer for crop antibacterial prepared by the present invention has a good preventive effect on common soil-borne diseases of crops such as wilt, root rot, sheath blight, damping-off and the like, and is particularly effective in preventing rice sheath blight. When used, it is turned into the soil as a base fertilizer, and the dosage per mu is 20 kg.

[0031] Nano-scale sustained-release particles not only have the advantages of sustained-release preparations, but also have special advantages due to their small particle size. They can effectively prevent the degradation of loaded pesticides and improve biological activity, solubility and other properties. They have become a new research and development direction for pesticides. The present invention uses biochar-nano hydroxyapatite composite nanomaterials as nano sustained-release agents. The Ca content of nano hydroxyapatite is 1.33 mmol / l. 2+ / PO4 3- The ion exchange properties and the porous structure of biochar work together to disperse thiofuran evenly on the surface of the nano sustained-release agent under the action of the dispersant. 2+ Coordinate bonding) and physical adsorption, can achieve efficient loading of thiofluanid, drug loading can reach 278mg / g, drug release time can be extended to more than 60d, effectively prolonging the action time of the drug, to common soil-borne diseases of crops such as wilt, root rot, sheath blight, damping-off disease and other diseases have excellent prevention and control effects, especially excellent prevention and control effect of rice sheath blight. At the same time, the nano material of the present invention adopts biochar as the matrix load of a small amount of nano hydroxyapatite, the material preparation cost is low, the method is simple, can significantly improve soil permeability and nano hydroxyapatite can also promote the absorption and utilization of phosphorus by plant roots, enhance the resistance of plants, and play a better effect of preventing and controlling soil-borne diseases of crops after compounding with slow-release thiofluanid.

[0032] The walnut peel extract prepared by the present invention uses a choline chloride-lactic acid deep eutectic solvent miscible with water as a solvent to extract the active ingredients of the walnut peel, replacing traditional organic solvents (such as methanol), reducing toxicity by more than 90%, and the obtained extract contains multiple active ingredients such as juglone, polyphenols, and flavonoids, which have an inhibitory effect on the growth of various bacteria and fungi in the soil; the latter components adsorbed on the surface of the nano slow-release agent by physical action are not stable, and can be quickly desorbed and released after being applied to the soil, inhibiting the growth of pathogens and blocking early infection. The fast-acting components synergize with the thiofuran loaded by the nano slow-release agent, and the slow-release components maintain the antibacterial concentration for a long time, covering the entire disease cycle, achieving an organic combination of fast-acting and slow-release, which can better inhibit the growth of pathogens, especially reduce the incidence of rice sheath blight, and also reduce the large-scale use of chemical pesticides, thereby improving environmental safety.

[0033] The hydrophobicity and air permeability of the polyether-modified silicone in the coating liquid of the present invention can be combined with the thickening and water-retaining properties of sodium carboxymethyl cellulose to form a coating layer that can prevent water from penetrating too quickly and maintain gas exchange between the inside of the fertilizer and the outside. This synergistic effect helps to improve the stability and nutrient utilization rate of the fertilizer. At the same time, the coating liquid can not only protect the fertilizer particles, but also can synergize with the nutrients and antibacterial components in the fertilizer. By regulating the release rate of nutrients and the release mode of antibacterial components, the fertilizer is made more in line with the growth requirements of crops, thereby improving the yield and quality of crops.

[0034] The beneficial effects of the present invention are:

[0035] (1) The present invention utilizes a novel nano sustained-release agent to achieve the effective loading of thiofuran, and simultaneously combines it with walnut peel extract to achieve the organic combination of fast-acting components and long-acting components, thereby extending the duration of efficacy, reducing the amount of chemical pesticides used, improving safety, and utilizing agricultural waste (straw, walnut peel) as raw materials, thereby reducing the production cost of pesticides and fertilizers, resulting in significant economic benefits.

[0036] (2) The most suitable polyether-modified silicone and sodium carboxymethyl cellulose are used in combination as the coating liquid. The two work synergistically to regulate the release of nutrients and antibacterial components, making the fertilizer more in line with the growth needs of crops, thereby improving crop yield and quality;

[0037] (3) The present invention adopts a chemical fungicide thiophanate-methyl, a botanical antibacterial agent walnut peel extract and a specially prepared nano slow-release agent and fertilizer in a reasonable ratio and uses a slow-release coating technology, which not only achieves the purpose of normal fertilization of crops, but also effectively inhibits soil harmful pathogens, especially has an excellent effect on the prevention and control of rice sheath blight, improves the effective utilization rate of fertilizers, reduces the use of pesticides, reduces the resistance of crops to pesticides, reduces pollution to the environment, improves safety, and has good market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The surface morphology SEM images of the nano sustained-release agent prepared by the present invention, wherein a is the SEM image of wheat straw biochar after alkali treatment, b is the SEM image of the prepared nanohydroxyapatite, and c is the nano sustained-release agent of the present invention which is a biochar-nanohydroxyapatite composite nanomaterial;

[0039] Figure 2 The cumulative release curves of thiofuranamide under natural environment (25°C) for the nano slow-release agent loaded with thiofuranamide prepared in the performance test part of the present invention and the novel slow-release compound fertilizer for crop antibacterial use obtained in Comparative Example 1 are shown; Figure 2 The middle curve A is the nano sustained-release agent loaded with thiofuranamide; Figure 2 The middle curve B is the new slow-release controlled-release compound fertilizer for crop antibacterial use obtained in Comparative Example 1. DETAILED DESCRIPTION

[0040] The technical solution of the present invention will be further described below with reference to specific embodiments, but is not limited thereto.

[0041] Example 1

[0042] A novel slow-release compound fertilizer for crop antibacterial properties comprises 0.5 parts of thiofuran, 20 parts of a nano slow-release agent, 40 parts of a nitrogen, phosphorus and potassium compound fertilizer, 0.1 parts of a dispersant, 10 parts of a walnut peel extract, 20 parts of humic acid, 40 parts of decomposed poultry and livestock manure, 3 parts of polyether-modified silicone, 5 parts of sodium carboxymethyl cellulose and 10 parts of water; the dispersant is composed of polyethylene glycol octylphenyl ether and cocamidopropyl betaine in a mass ratio of 2:1.

[0043] The nano sustained-release agent is prepared by the following method:

[0044] A. Immerse 20g of wheat straw biochar in 100ml of 2mol / L sodium hydroxide solution, stir at 45℃ for 2-3h, filter and wash until neutral, then dry to obtain alkaline biochar;

[0045] B. Prepare a 0.5 mol / L Ca(NO3)2 solution by adding Ca(NO3)2·4H2O, then add aqueous ammonia to adjust the pH of the solution to 10.5, and then add an equal volume of 0.5 mol / L ammonium dihydrogen phosphate solution. Stir the mixture at room temperature for 2 hours, then heat to 40°C and allow to stand for 12-16 hours. Afterwards, filter the mixture and wash it alternately with deionized water and ethanol for more than three times. Dry the mixture in an oven at 80°C for 10 hours to obtain nanohydroxyapatite.

[0046] C. Weigh 0.5 g of the nanohydroxyapatite obtained in step B, add it to 50 ml of deionized water, and ultrasonically disperse it for 30 minutes to obtain a nanohydroxyapatite suspension;

[0047] D. Soak the alkaline biochar obtained in step A in the nanohydroxyapatite suspension obtained in step C, stir magnetically at 25°C for 45-60 minutes, filter and wash until neutral, dry in an oven, and grind through a 200-mesh sieve to obtain the product biochar-nanohydroxyapatite composite nanomaterial; the usage ratio of alkaline biochar to nanohydroxyapatite suspension is 1g:50ml.

[0048] The walnut green peel extract is prepared by the following method:

[0049] (1) Washing fresh walnut green peel, vacuum drying at 40° C. to a moisture content of ≤8%, freezing with liquid nitrogen, and then pulverizing to a particle size of ≤50 μm to obtain walnut green peel powder;

[0050] (2) The walnut peel powder was mixed with the solvent at a solid-liquid ratio of 1 g:10 ml, and ultrasonic treatment was performed at a power of 300 W and 28 kHz for 5 min. After the ultrasonic treatment, the pH of the mixture was adjusted to 5.0, and a complex enzyme was added thereto. The mixture was hydrolyzed at 45 ° C for 2 h, the enzyme was inactivated, and the mixture was centrifuged. The supernatant was vacuum freeze-dried to obtain powder.

[0051] The complex enzyme is composed of cellulase and laccase in a mass ratio of 2:1; the enzyme activity of the laccase is 100,000 u / g, and the enzyme activity of the cellulase is 20,000 u / g.

[0052] The solvent is composed of a choline chloride-lactic acid deep eutectic solvent and deionized water in a volume ratio of 3:7; the choline chloride-lactic acid deep eutectic solvent has a molar ratio of choline chloride to lactic acid of 1:2. The specific method is: choline chloride and lactic acid are mixed in a molar ratio, heated to 60°C, and reacted with magnetic stirring for 4-6 hours to obtain the obtained solvent.

[0053] The preparation method of the polyether-modified silicone is as follows:

[0054] Step 1: 40 ml of polyetheramine and 36.5 g of 1,1,3,3-tetramethyl-1,3-bis-[3-(oxiranylmethoxy)propyl]disiloxane were placed in a reactor, 200 ml of isopropanol was added as a solvent, the temperature was raised to 100° C., and the reaction was carried out for 3 to 6 hours until the system became clear, thereby obtaining intermediate product A;

[0055] Step 2: Cool the intermediate product A to room temperature, add 4 g of tetramethylammonium hydroxide, stir evenly and raise the temperature to 100°C. After reacting for 30 minutes, add 99.5 g of octamethylcyclotetrasiloxane and 25 g of 3-(trimethoxysilyl)propyldimethyloctadecylammonium chloride, stir and mix evenly and continue to react for 2 hours. Then, vacuum the system to remove small molecular impurities, and continue to react at 100°C until the viscosity of the system no longer changes. The product obtained is polyether-modified silicone.

[0056] The nitrogen, phosphorus and potassium compound fertilizer used is a general compound fertilizer (N-P2O5-K2O: 15-15-15).

[0057] A method for preparing the novel slow-release controlled-release compound fertilizer for crop antibacterial use comprises the following steps:

[0058] 1) preparing walnut green peel extract;

[0059] 2) preparing nano sustained-release agents;

[0060] 3) Thifluzamide and the dispersant were mixed uniformly, then added to the nano sustained-release agent, stirred and mixed at room temperature for 30 minutes, allowed to stand for 4 hours, and then vacuum freeze-dried to obtain premix A;

[0061] 4) Premix A, walnut peel extract, nitrogen, phosphorus and potassium compound fertilizer, humic acid, and decomposed livestock manure are ground separately and passed through a 60-mesh sieve, mixed evenly according to proportion, and then wet granulated to obtain fertilizer granules;

[0062] 5) The polyether-modified organic silicon, sodium carboxymethyl cellulose and water are mixed evenly to obtain a uniform coating liquid, which is evenly sprayed onto the surface of the medicated fertilizer particles obtained in step 4), and then dried.

[0063] Example 2

[0064] A novel slow-release compound fertilizer for crop antibacterial properties is prepared from 1 part of thiofuran, 30 parts of a nano slow-release agent, 50 parts of a nitrogen, phosphorus and potassium compound fertilizer, 0.3 parts of a dispersant, 15 parts of a walnut peel extract, 30 parts of humic acid, 60 parts of decomposed poultry and livestock manure, 5 parts of polyether-modified silicone, 8 parts of sodium carboxymethyl cellulose and 20 parts of water; the dispersant is composed of polyethylene glycol octylphenyl ether and cocamidopropyl betaine in a mass ratio of 2:1.

[0065] The nano sustained-release agent is prepared by the following method:

[0066] A. Immerse 20g of wheat straw biochar in 100ml of 2mol / L sodium hydroxide solution, stir at 45℃ for 2-3h, filter and wash until neutral, then dry to obtain alkaline biochar;

[0067] B. Prepare a 0.5 mol / L Ca(NO3)2 solution by taking Ca(NO3)2·4H2O, then add ammonia water to adjust the pH value of the solution to 10.5, and then add an equal volume of 0.5 mol / L ammonium dihydrogen phosphate solution. After stirring at room temperature for 2 hours, heat to 40°C and continue to stand for 12-16 hours. After completion, filter and wash alternately with deionized water and ethanol for more than 3 times, and dry in an oven at 80°C for 10 hours to obtain nanohydroxyapatite.

[0068] C. Weigh 0.5 g of the nanohydroxyapatite obtained in step B, add it to 50 ml of deionized water, and ultrasonically disperse it for 30 minutes to obtain a nanohydroxyapatite suspension;

[0069] D. Soak the alkaline biochar obtained in step A in the nanohydroxyapatite suspension obtained in step C, stir magnetically at 25°C for 45-60 minutes, filter and wash until neutral, dry in an oven, and grind through a 200-mesh sieve to obtain the product biochar-nanohydroxyapatite composite nanomaterial; the usage ratio of alkaline biochar to nanohydroxyapatite suspension is 1g:50ml.

[0070] The walnut green peel extract is prepared by the following method:

[0071] (1) Washing fresh walnut green peel, vacuum drying at 40° C. to a moisture content of ≤8%, freezing with liquid nitrogen, and then pulverizing to a particle size of ≤50 μm to obtain walnut green peel powder;

[0072] (2) The walnut peel powder was mixed with the solvent at a solid-liquid ratio of 1 g:10 ml, and ultrasonic treatment was performed at a power of 300 W and 28 kHz for 5 min. After the ultrasonic treatment, the pH of the mixture was adjusted to 5.0, and a complex enzyme was added thereto. The mixture was hydrolyzed at 45 ° C for 2 h, the enzyme was inactivated, and the mixture was centrifuged. The supernatant was vacuum freeze-dried to obtain powder.

[0073] The complex enzyme is composed of cellulase and laccase in a mass ratio of 2:1; the enzyme activity of the laccase is 100,000 u / g, and the enzyme activity of the cellulase is 20,000 u / g.

[0074] The solvent is composed of a choline chloride-lactic acid deep eutectic solvent and deionized water in a volume ratio of 3:7; the choline chloride-lactic acid deep eutectic solvent has a molar ratio of choline chloride to lactic acid of 1:2. The specific method is: choline chloride and lactic acid are mixed in a molar ratio, heated to 60°C, and reacted with magnetic stirring for 4-6 hours to obtain the obtained solvent.

[0075] The preparation method of the polyether-modified silicone is as follows:

[0076] Step 1: 40 ml of polyetheramine and 36.5 g of 1,1,3,3-tetramethyl-1,3-bis-[3-(oxiranylmethoxy)propyl]disiloxane were placed in a reactor, 200 ml of isopropanol was added as a solvent, the temperature was raised to 100° C., and the reaction was carried out for 3 to 6 hours until the system became clear, thereby obtaining intermediate product A;

[0077] Step 2: Cool the intermediate product A to room temperature, add 4 g of tetramethylammonium hydroxide, stir evenly and raise the temperature to 100°C. After reacting for 30 minutes, add 99.5 g of octamethylcyclotetrasiloxane and 25 g of 3-(trimethoxysilyl)propyldimethyloctadecylammonium chloride, stir and mix evenly and continue to react for 2 hours. Then, vacuum the system to remove small molecular impurities, and continue to react at 100°C until the viscosity of the system no longer changes. The product obtained is polyether-modified silicone.

[0078] The nitrogen, phosphorus and potassium compound fertilizer used is a general compound fertilizer (N-P2O5-K2O: 15-15-15).

[0079] A method for preparing the novel slow-release controlled-release compound fertilizer for crop antibacterial use comprises the following steps:

[0080] 1) preparing walnut green peel extract;

[0081] 2) preparing nano sustained-release agents;

[0082] 3) Thifluzamide and the dispersant were mixed uniformly, then added to the nano sustained-release agent, stirred and mixed at room temperature for 30 minutes, allowed to stand for 4 hours, and then vacuum freeze-dried to obtain premix A;

[0083] 4) Premix A, walnut peel extract, nitrogen, phosphorus and potassium compound fertilizer, humic acid, and decomposed livestock manure are ground separately and passed through a 60-mesh sieve, mixed evenly according to proportion, and then wet granulated to obtain fertilizer granules;

[0084] 5) The polyether-modified organic silicon, sodium carboxymethyl cellulose and water are mixed evenly to obtain a uniform coating liquid, which is evenly sprayed onto the surface of the medicated fertilizer particles obtained in step 4), and then dried.

[0085] Example 3

[0086] A novel slow-release compound fertilizer for crop antibacterial properties is prepared from 0.8 parts of thiofuran, 25 parts of a nano slow-release agent, 45 parts of a nitrogen, phosphorus and potassium compound fertilizer, 0.2 parts of a dispersant, 12 parts of a walnut peel extract, 25 parts of humic acid, 50 parts of decomposed poultry and livestock manure, 4 parts of polyether-modified silicone, 6 parts of sodium carboxymethyl cellulose and 15 parts of water; the dispersant is composed of polyethylene glycol octylphenyl ether and cocamidopropyl betaine in a mass ratio of 2:1.

[0087] The nano sustained-release agent is prepared by the following method:

[0088] A. Immerse 20g of wheat straw biochar in 100ml of 2mol / L sodium hydroxide solution, stir at 45℃ for 2-3h, filter and wash until neutral, then dry to obtain alkaline biochar;

[0089] B. Prepare a 0.5 mol / L Ca(NO3)2 solution by taking Ca(NO3)2·4H2O, then add ammonia water to adjust the pH value of the solution to 10.5, and then add an equal volume of 0.5 mol / L ammonium dihydrogen phosphate solution. After stirring at room temperature for 2 hours, heat to 40°C and continue to stand for 12-16 hours. After completion, filter and wash alternately with deionized water and ethanol for more than 3 times, and dry in an oven at 80°C for 10 hours to obtain nanohydroxyapatite.

[0090] C. Weigh 0.5 g of the nanohydroxyapatite obtained in step B, add it to 50 ml of deionized water, and ultrasonically disperse it for 30 minutes to obtain a nanohydroxyapatite suspension;

[0091] D. Soak the alkaline biochar obtained in step A in the nanohydroxyapatite suspension obtained in step C, stir magnetically at 25°C for 45-60 minutes, filter and wash until neutral, dry in an oven, and grind through a 200-mesh sieve to obtain the product biochar-nanohydroxyapatite composite nanomaterial; the usage ratio of alkaline biochar to nanohydroxyapatite suspension is 1g:50ml.

[0092] The walnut green peel extract is prepared by the following method:

[0093] (1) Washing fresh walnut green peel, vacuum drying at 40° C. to a moisture content of ≤8%, freezing with liquid nitrogen, and then pulverizing to a particle size of ≤50 μm to obtain walnut green peel powder;

[0094] (2) The walnut peel powder was mixed with the solvent at a solid-liquid ratio of 1 g:10 ml, and ultrasonic treatment was performed at a power of 300 W and 28 kHz for 5 min. After the ultrasonic treatment, the pH of the mixture was adjusted to 5.0, and a complex enzyme was added thereto. The mixture was hydrolyzed at 45 ° C for 2 h, the enzyme was inactivated, and the mixture was centrifuged. The supernatant was vacuum freeze-dried to obtain powder.

[0095] The complex enzyme is composed of cellulase and laccase in a mass ratio of 2:1; the enzyme activity of the laccase is 100,000 u / g, and the enzyme activity of the cellulase is 20,000 u / g.

[0096] The solvent is composed of a choline chloride-lactic acid deep eutectic solvent and deionized water in a volume ratio of 3:7; the choline chloride-lactic acid deep eutectic solvent has a molar ratio of choline chloride to lactic acid of 1:2. The specific method is: choline chloride and lactic acid are mixed in a molar ratio, heated to 60°C, and reacted with magnetic stirring for 4-6 hours to obtain the obtained solvent.

[0097] The preparation method of the polyether-modified silicone is as follows:

[0098] Step 1: 40 ml of polyetheramine and 36.5 g of 1,1,3,3-tetramethyl-1,3-bis-[3-(oxiranylmethoxy)propyl]disiloxane were placed in a reactor, 200 ml of isopropanol was added as a solvent, the temperature was raised to 100° C., and the reaction was carried out for 3 to 6 hours until the system became clear, thereby obtaining intermediate product A;

[0099] Step 2: Cool the intermediate product A to room temperature, add 4 g of tetramethylammonium hydroxide, stir evenly and raise the temperature to 100°C. After reacting for 30 minutes, add 99.5 g of octamethylcyclotetrasiloxane and 25 g of 3-(trimethoxysilyl)propyldimethyloctadecylammonium chloride, stir and mix evenly and continue to react for 2 hours. Then, vacuum the system to remove small molecular impurities, and continue to react at 100°C until the viscosity of the system no longer changes. The product obtained is polyether-modified silicone.

[0100] The nitrogen, phosphorus and potassium compound fertilizer used is a general compound fertilizer (N-P2O5-K2O: 15-15-15).

[0101] A method for preparing the novel slow-release controlled-release compound fertilizer for crop antibacterial use comprises the following steps:

[0102] 1) preparing walnut green peel extract;

[0103] 2) preparing nano sustained-release agents;

[0104] 3) Thifluzamide and the dispersant were mixed uniformly, then added to the nano sustained-release agent, stirred and mixed at room temperature for 30 minutes, allowed to stand for 4 hours, and then vacuum freeze-dried to obtain premix A;

[0105] 4) Premix A, walnut peel extract, nitrogen, phosphorus and potassium compound fertilizer, humic acid, and decomposed livestock manure are ground separately and passed through a 60-mesh sieve, mixed evenly according to proportion, and then wet granulated to obtain fertilizer granules;

[0106] 5) The polyether-modified organic silicon, sodium carboxymethyl cellulose and water are mixed evenly to obtain a uniform coating liquid, which is evenly sprayed onto the surface of the medicated fertilizer particles obtained in step 4), and then dried.

[0107] Comparative Example 1

[0108] A novel slow-release compound fertilizer for crop antibacterial use, whose principle, composition and preparation method are basically the same as those in Example 3, the only difference being that it does not contain a nano slow-release agent and the corresponding preparation method.

[0109] Comparative Example 2

[0110] A novel slow-release compound fertilizer for antibacterial use in crops, whose principle, composition and preparation method are basically the same as those in Example 3, except that it does not contain walnut green peel extract and the corresponding preparation method steps.

[0111] Comparative Example 3

[0112] A novel slow-release compound fertilizer for crop antibacterial treatment has the same principle, composition and preparation method as that in Example 3, except that the nano slow-release agent is commercially available wheat straw biochar.

[0113] Comparative Example 4

[0114] A novel slow-release compound fertilizer for crop antibacterial use, the principle, composition and preparation method of which are basically the same as those in Example 3, the only difference being that thiophanate-methyl is not contained.

[0115] Comparative Example 5

[0116] A novel slow-release compound fertilizer for crop antibacterial use, the principle, composition and preparation method of which are basically the same as those in Example 3, except that neither thiophanate nor walnut peel extract is contained. The specific preparation method of the compound fertilizer is as follows: 1) preparing a nano slow-release agent;

[0117] 2) The nano slow-release agent, nitrogen, phosphorus and potassium compound fertilizer, humic acid and decomposed livestock manure are respectively ground and passed through a 60-mesh sieve, mixed evenly with the dispersant in proportion, and then wet granulated to obtain the fertilizer granules;

[0118] 3) The polyether-modified organic silicon, sodium carboxymethyl cellulose and water are mixed evenly to obtain a uniform coating liquid, which is evenly sprayed onto the surface of the medicated fertilizer particles obtained in step 2), and then dried.

[0119] Performance Testing

[0120] The surface morphology of the nano sustained-release agent prepared by the present invention was tested, as shown in FIG. Figure 1 As shown, from Figure 1 It can be seen that the wheat straw biochar has rich surface pores and large specific surface area after alkali treatment; the nanohydroxyapatite is in the form of small spheres and aggregates more, and the adsorption active sites are reduced due to aggregation; the prepared biochar-nanohydroxyapatite composite nanomaterial biochar shows that it still maintains the original porous structure and the spherical nanohydroxyapatite is dispersed on the surface and pores of the biochar, which can increase more adsorption active sites, so that more active ingredients of the drug can be adsorbed into the pores, increasing the drug loading capacity.

[0121] The drug loading and release performance test of the nano sustained-release agent of the present invention was carried out as follows: 5 g of thiofluzamide and 200 ml of anhydrous ethanol were prepared into a mixed solution, 20 g of the nano sustained-release agent prepared by the present invention was added thereto, and after stirring at room temperature for 2 h, the solvent was removed by rotary evaporation to obtain the nano sustained-release agent loaded with thiofluzamide.

[0122] 1 g of the nano-sustained-release agent loaded with thiofluzamide prepared above was mixed with 50 ml of acetone, stirred at 500 r / min for 30 h, centrifuged (10000 rpm, 10 min), and the supernatant was measured by UV-visible spectrophotometry at 220 nm. The absorbance was calculated by the standard concentration curve: A = 0.0125C + 0.001 (R 2 =0.9996) to quantify the thiofuranamide content and calculate the drug loading amount. The drug loading amount calculation formula is as follows:

[0123] Drug loading (mg / g) = (C×V) / W

[0124] C: Thiofuramide concentration in the supernatant (mg / mL);

[0125] V: supernatant volume (mL);

[0126] W: mass of the nano sustained-release agent (g). The results showed that the drug loading of thiofluzamide was 278 mg / g.

[0127] Take 1g of the nano sustained-release agent loaded with thiofluanid prepared above, use methanol: water mixed solution (30:70, v:v) as the release medium, disperse it in 500ml of methanol-water mixed solution, stir the solution at 500r / min under natural light, take 2ml of solution every 2d for centrifugation (10000rpm, 10min) except the first test, and supplement 2ml of methanol: water mixed solution to be tested in the sample solution; at the same time, the compound fertilizer prepared in Comparative Example 1 was tested under the same conditions as above as a blank comparative example. The concentration of thiofluanid in the supernatant was measured by ultraviolet-visible spectrophotometer to obtain the cumulative release rate of the drug at different times ( Figure 2 ).from Figure 2 It can be seen that the release time of thiofuranamide can be up to 60 days, which effectively prolongs the action time of the drug. In contrast, the drug (thiofuranamide) in Comparative Example 1 that does not use a nano sustained-release agent reaches a release equilibrium point in about 24 days.

[0128] The nitrogen release rates of the novel slow-release and controlled-release compound fertilizers for crop antibacterial use obtained in some examples and comparative examples of the present invention were measured in accordance with the national standard (GB / T) 23348-2009 for slow-release fertilizers. After immersion in still water at 25°C for 24 hours, the initial nutrient release rate of the slow-release fertilizers was less than 15%, and the cumulative nutrient release rate over 28 days was less than 80%. The specific results are shown in Table 1.

[0129] Table 1 Nitrogen release rate of different slow-release compound fertilizers for antibacterial use in crops

[0130]

[0131]

[0132] It can be seen from the results in Table 1 above that the novel slow-release compound fertilizer for antibacterial use in crops prepared in the embodiment of the present invention has a prolonged fertilizer effect and a significant slow-release effect compared with ordinary fertilizers on the market, which can prolong the fertilizer effect and improve the fertilizer utilization rate.

[0133] Application experiment on control of rice sheath blight

[0134] Experimental site and methods: A farmland in Tangpo Village, Nuodong Town, Wuzhou City, Guangxi Zhuang Autonomous Region, where rice cultivation has been plagued by sheath blight for many years. The experimental site was divided into 10 treatment groups, each with an area of ​​50m 2 The rice variety planted was Suixiangyou 9168. The rice variety and planting method were the same in each treatment group. Treatment groups 1-3 used the new slow-release compound antibacterial fertilizer for crops prepared in Examples 1-3 as base fertilizer at a dosage of 20 kg / mu; treatment groups 4-8 used the new slow-release compound antibacterial fertilizer for crops prepared in Comparative Examples 1-5 as base fertilizer at a dosage of 20 kg / mu; treatment group 9 used 30 kg / mu of commercially available ordinary ternary compound fertilizer (15-15-15) + 500 g / mu of thiophanate-methyl thiophanate granules (purchased from Hebei Bojia Agriculture Co., Ltd.) as base fertilizer and turned into the soil for use; treatment group 10 used only 30 kg / mu of commercially available ordinary ternary compound fertilizer (15-15-15) as a blank control; all treatment groups were topdressed with 3 kg / mu of potassium chloride during the rice heading period. In addition, no fertilizers, pesticides or biological control agents were applied during the entire growth period. The other management measures were all conventional rice field management measures. The occurrence of sheath blight in each treatment group during the entire growth cycle of rice was counted, and the number of diseased plants and severity were recorded.

[0135] Survey Method: Sheath blight disease was investigated every 5-7 days, starting 30 days after transplanting. Fifteen sites were surveyed per treatment, with five plants selected from each site. The diseased plant rate, disease index, and control efficacy were determined. At harvest, the number of effective ears and filled grains per ear were investigated, and the thousand-grain weight was measured to calculate theoretical yield.

[0136] The severity grading standards for rice sheath blight are as follows:

[0137] Level 0: The whole plant is disease-free.

[0138] Level 1: The disease occurs in every leaf sheath or leaf below the third leaf (starting from the top, the same below).

[0139] Level 2: The disease occurs in the leaf sheaths or leaves below the second leaf.

[0140] Level 3: The disease occurs in the top leaf sheath or top leaf.

[0141] Level 4: The whole plant is diseased and dies prematurely.

[0142] The relevant indicators are calculated as follows:

[0143] Diseased plant rate (%) = number of diseased plants / total number of surveyed plants × 100;

[0144]

[0145] Control effect (%) = (disease index in control area - disease index in treated area) / disease index in control area × 100.

[0146] Table 2 Control effect of rice sheath blight

[0147]

[0148] From the results in Table 2, it can be seen that compared with the blank control group, the novel slow-release compound fertilizer for crop antibacterial treatment prepared in Examples 1-3 of the present invention has a significantly higher control effect on rice sheath blight than that in Comparative Examples 1-5, and is also higher than the commercially available product, thiophanate-methyl granules. This is mainly because the present invention adopts a specific nano-sustained-release material as an adsorbent, and the nano-material can achieve an effective load of thiophanate-methyl, thereby prolonging the drug action time and achieving long-term control of rice sheath blight. At the same time, the walnut peel extract contains an active ingredient, which realizes an organic combination of fast-acting and long-acting effects with the slow-release thiophanate-methyl. The two act synergistically, covering the entire disease cycle, can better inhibit the growth of pathogens, reduce the incidence of rice sheath blight, and at the same time reduce the large-scale use of chemical pesticides, thereby improving environmental safety.

[0149] Table 3 Rice yield and composition in different treatment groups

[0150]

[0151]

[0152] From the data in Table 3 above, it can be seen that the yields of Examples 1-3 are significantly higher than those of the other treatment groups, with an increase of about 20% over the control, indicating that the composite fertilizer of the present invention effectively improves the number of effective ears, the number of grains per ear, and the thousand-grain weight through the synergistic effect of the nano slow-release agent and the walnut green peel extract. The yield of Comparative Example 1 (without nano slow-release agent) is only 540kg / mu (yield increase of 5.9%), indicating that the nano slow-release agent of the present invention is crucial for the continuous supply of nutrient dry antibacterial components; the yield of Comparative Example 5 (without antibacterial components) (511kg / mu) is close to that of the blank control (510kg / mu), indicating the key role of antibacterial components in disease prevention and control and yield increase. The effect of commercially available compound fertilizer + thiothiocarb granules (575kg / mu, 12.7% increase) is still lower than that of the embodiment group, highlighting the advantages of the present invention in slow-release efficiency and synergistic synergy.

[0153] It should be noted that the above embodiments are only some of the preferred embodiments of the present invention, and not all of them. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

Claims

1. A novel slow-release compound fertilizer for crop antibacterial, characterized in that: The invention is prepared from the following raw materials in parts by weight: 0.5-1 parts of thiofuran, 20-30 parts of nano slow-release agent, 40-50 parts of nitrogen, phosphorus and potassium compound fertilizer, 0.1-0.3 parts of dispersant, 10-15 parts of walnut peel extract, 20-30 parts of humic acid, 40-60 parts of decomposed poultry and livestock feces, 3-5 parts of polyether-modified organic silicon, 5-8 parts of sodium carboxymethyl cellulose, and 10-20 parts of water; the dispersant is composed of polyethylene glycol octylphenyl ether and cocamidopropyl betaine in a mass ratio of 2:1; The nano sustained-release agent is prepared by the following method: A. Take wheat straw biochar and immerse it in sodium hydroxide solution for alkaline treatment to obtain alkaline biochar; B. Prepare Ca(NO3)2·4H2O into a Ca(NO3)2 solution, then add ammonia water to adjust the pH of the solution to 10.5, then add an equal volume of ammonium dihydrogen phosphate solution, stir at room temperature for 2 hours, heat to 40°C and continue to stand for 12-16 hours, filter and wash alternately with deionized water and ethanol for more than 3 times, and dry in an oven to obtain nanohydroxyapatite; C. Weigh 0.5 g of the nanohydroxyapatite obtained in step B, add it to 50 ml of deionized water, and ultrasonically disperse it for 30 minutes to obtain a nanohydroxyapatite suspension; D. Soak the alkaline biochar obtained in step A in the nanohydroxyapatite suspension obtained in step C, stir magnetically at 25° C. for 45-60 minutes, filter and wash to neutrality, dry in an oven, and grind through a 200-mesh sieve to obtain the product biochar-nanohydroxyapatite composite nanomaterial.

2. The novel slow-release compound fertilizer for antibacterial use in crops according to claim 1, characterized in that: The specific alkaline treatment method of step A is as follows: immersing 20 g of wheat straw biochar in 100 ml of 2 mol / L sodium hydroxide solution, stirring at 45° C. for 2-3 hours, filtering and washing to neutrality, and then drying to obtain alkaline biochar.

3. The novel slow-release compound fertilizer for crop antibacterial use according to claim 1, characterized in that: In step B, the concentration of the Ca(NO3)2 solution is 0.5 mol / L, and the concentration of the ammonium dihydrogen phosphate solution is 0.5 mol / L.

4. The novel slow-release compound fertilizer for antibacterial use in crops according to claim 1, characterized in that: In the step D, the ratio of alkaline biochar to nano-hydroxyapatite suspension is 1 g:50 ml.

5. The novel slow-release compound fertilizer for antibacterial use in crops according to claim 1, characterized in that: The walnut green peel extract is prepared by the following method: (1) Fresh walnut green peel was washed and vacuum dried at 40°C to a moisture content of ≤8%, then frozen with liquid nitrogen and pulverized to a particle size of ≤50 μm to obtain walnut green peel powder; (2) The walnut peel powder was mixed with the solvent at a solid-liquid ratio of 1 g:10 ml, and ultrasonic treatment was performed at a power of 300 W and 28 kHz for 5 min. After the ultrasonic treatment, the pH of the mixture was adjusted to 5.0, and the complex enzyme was added to the mixture. The mixture was enzymatically hydrolyzed at 45 °C for 2 h, the enzyme was inactivated, and the mixture was centrifuged. The supernatant was vacuum freeze-dried to obtain powder.

6. The novel slow-release compound fertilizer for antibacterial use in crops according to claim 5, characterized in that: The complex enzyme is composed of cellulase and laccase in a mass ratio of 2:1; the enzyme activity of the laccase is 100,000 u / g, and the enzyme activity of the cellulase is 20,000 u / g.

7. The novel slow-release compound fertilizer for antibacterial use in crops according to claim 5, characterized in that: The solvent is composed of a choline chloride-lactic acid deep eutectic solvent and deionized water in a volume ratio of 3:7; the molar ratio of choline chloride to lactic acid in the choline chloride-lactic acid deep eutectic solvent is 1:

2.

8. The novel slow-release compound fertilizer for antibacterial use in crops according to claim 1, characterized in that: The preparation method of the polyether-modified silicone is as follows: Step 1: Place 40 ml of polyetheramine and 36.5 g of 1,1,3,3-tetramethyl-1,3-bis-[3-(oxiranylmethoxy)propyl]disiloxane into a reactor, add 200 ml of isopropanol as a solvent, heat to 100 °C, and react for 3-6 hours until the system becomes clear to obtain intermediate product A. Step 2: Cool the intermediate product A to room temperature, add 4 g of tetramethylammonium hydroxide, stir evenly and heat to 100°C. After reacting for 30 minutes, add 99.5 g of octamethylcyclotetrasiloxane and 25 g of 3-(trimethoxysilyl)propyldimethyloctadecylammonium chloride, stir and mix evenly and continue to react for 2 hours. Then, vacuum the system to remove small molecular impurities, and continue to react at 100°C until the viscosity of the system no longer changes. The product obtained is polyether-modified silicone.

9. A method for preparing a novel slow-release and controlled-release compound fertilizer for crop antibacterial use according to any one of claims 1 to 8, characterized in that: It includes the following steps: 1) Preparation of walnut green peel extract; 2) Preparation of nano sustained-release agents; 3) Thifluzamide and the dispersant were mixed evenly, then added to the nano sustained-release agent, stirred and mixed at room temperature for 30 minutes, allowed to stand for 4 hours, and then vacuum freeze-dried to obtain premix A; 4) Premix A, walnut peel extract, nitrogen, phosphorus and potassium compound fertilizer, humic acid, and decomposed livestock manure are ground separately and passed through a 60-mesh sieve, mixed evenly according to the proportion, and then wet granulated to obtain fertilizer granules; 5) The polyether-modified silicone, sodium carboxymethyl cellulose and water are mixed evenly to obtain a uniform coating liquid, which is evenly sprayed onto the surface of the medicated fertilizer particles obtained in step 4), and then dried.

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