Insect pest prevention chemical fertilizer for vegetables and preparation method of insect pest prevention chemical fertilizer

Abstract

The invention discloses an insect pest prevention chemical fertilizer for vegetables and a preparation method thereof, and relates to the field of chemical fertilizers. Nano silicon dioxide is used as a silicon fertilizer main body, the nano silicon dioxide, sodium bicarbonate and calcium citrate are subjected to spray drying to prepare composite particles, the composite particles are mixed with the self-made pH response insect pest prevention microcapsules and then sprayed to vegetable leaf surfaces, when pests eat the composite particles, acidic substances in oral saliva react with components in the composite particles to enable local pH to be increased, the microcapsules are promoted to be broken, and the insect pest prevention effect is achieved. Terpenoids and jasmonic acid methyl ester are rapidly released, feeding and physiological activities of pests are inhibited, and meanwhile vegetables are induced to start a defense mechanism; the pH response insect pest prevention microcapsule is prepared by taking oxidized paraffin prepared by a biological enzyme catalytic oxidation method as a main wall material, wrapping a core material by adopting an oil-in-water emulsification method, and performing chemical crosslinking on the core material and a polylactic acid-maleic anhydride copolymer, and can quickly release the core material in a weakly alkaline environment and slowly release the core material in a daily process to realize long-acting insect pest prevention. The insect pest prevention chemical fertilizer for vegetables prepared by the invention has an insect pest prevention effect.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical fertilizers, and specifically relates to a chemical fertilizer for pest-resistant vegetables and a preparation method thereof. Background Art

[0002] In the current prevention and control of vegetable pests, traditional chemical pesticides have problems such as excessive residues, enhanced pest resistance, and environmental pollution. And the green prevention and control technology based on the plant defense mechanism is difficult to achieve a precise response to the feeding behavior of pests due to its slow action and insufficient pertinence. Although silicon fertilizer can enhance the stress resistance of plants and induce the formation of silicified cells to form a "mechanical fence", there is a lack of a synergistic response mechanism with pest stress when applied alone.

[0003] The microcapsule slow-release technology can improve the controllability of pesticide release. However, the existing pH-responsive microcapsules generally have defects such as insufficient environmental friendliness of the wall material, inaccurate release signal response, poor storage stability, and it is difficult to form a linkage with the plant's own defense system. In addition, conventional pest control components mostly rely on chemical synthetic wall materials for encapsulation, and their degradation products may pose potential risks to the soil and crops. Therefore, there is an urgent need to develop a new type of chemical fertilizer that combines environmental friendliness, precise response, and long-term prevention and control.

[0004] In view of the above problems, the present invention designs a synergistic system of pH-responsive pest control microcapsules and silicon-based composite particles to achieve the dual activation of precise release during pest feeding and the plant defense mechanism. At the same time, an environmentally friendly wall material is prepared by the bioenzyme-catalyzed oxidation method, solving the technical bottleneck that it is difficult to balance precision, long-term effectiveness, and environmental friendliness in the existing technology. Summary of the Invention

[0005] The purpose of the present invention is to provide a chemical fertilizer for pest-resistant vegetables and a preparation method thereof to solve the problems existing in the prior art.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: A chemical fertilizer for pest-resistant vegetables, and the preparation method of the chemical fertilizer for pest-resistant vegetables includes the following steps:

[0007] A preparation method of a chemical fertilizer for pest-resistant vegetables, characterized in that it includes 20-30 parts of composite particles, 20-30 parts of pest control microcapsules, 10-15 parts of potassium dihydrogen phosphate, and 10-15 parts of urea by weight;

[0008] The preparation method of the composite particles is: Mix nano-silica, sodium bicarbonate, calcium citrate, and deionized water in a mass ratio of 6-8:1-3:1:50, stir at 1000 rpm for 30 min, and then obtain composite particles with a particle size of 20-50 μm by spray drying;

[0009] The preparation method of the pest control microcapsules is:

[0010] (1) Mix the biocatalyst with the buffer solution to prepare an enzyme activation solution with a concentration of 1 mg / ml and a pH of 6 - 7. Mix the powdered paraffin with the enzyme activation solution at a mass ratio of 1:0.1 - 0.3, stir at 30 - 40 °C at 300 rpm for 10 min, then add an oxidant 4 - 6 times the mass of the paraffin dropwise to the mixture at a rate of 2 ml / min. Keep stirring and reacting for 8 - 12 h, then cool to room temperature. Add an organic solvent 30 - 40 times the mass of the paraffin, stir at 100 rpm for 10 min, and then centrifuge at 4000 rpm for 10 min. Distill the supernatant at 50 - 60 °C and a vacuum of -0.1 MPa for 1 - 2 h, and then dry the solid in an oven at 30 °C for 12 h to obtain oxidized paraffin.

[0011] (2) Mix the terpene compound, methyl jasmonate, and ethanol at a mass ratio of 2 - 4:0.5 - 1.5:20 and stir at 200 rpm for 10 min to obtain an oil-phase solution. Heat the oxidized paraffin to 60 °C to melt it, then mix it with a surfactant, a cross-linking agent, and deionized water at a mass ratio of 1:0.05 - 0.15:0.01 - 0.03:10, and stir at 200 rpm for 30 min to form an aqueous-phase solution. Add the aqueous-phase solution to the oil-phase solution, emulsify it with an emulsifier at 2000 rpm for 30 min to form an oil-in-water emulsion, then add a polylactic acid - maleic anhydride polymer 0.2 - 0.3 times the mass of the oxidized paraffin, stir and react at 40 °C and 200 rpm for 4 h. Filter the reaction solution, wash the filter cake with deionized water 2 - 4 times, and dry it at 30 °C for 12 h to obtain pest-control microcapsules with a particle size of 400 - 500 μm.

[0012] Further, the particle size of the nano-silica in step (1) is: 50 - 100 nm.

[0013] Further, the biocatalyst in step (2) is: horseradish peroxidase.

[0014] Further, the powdered paraffin in step (2) is: with a particle size of 100 μm.

[0015] Further, the buffer solution in step (2) is: phosphate buffer solution.

[0016] Further, the oxidant in step (2) is: 30 wt% H2O2 aqueous solution.

[0017] Further, the organic solvent in step (2) is: petroleum ether.

[0018] Further, the terpene compound in step (3) is: menthol.

[0019] Further, the surfactant in step (3) is: polysorbate 80.

[0020] Further, the crosslinking agent described in step (3) is: citric acid.

[0021] Further, for the application of a chemical fertilizer for pest - resistant vegetables, it is characterized in that the chemical fertilizer and deionized water are mixed at a mass ratio of 1:50, stirred at 150 rpm for 10 min at room temperature to form a spraying solution, and uniformly sprayed on the vegetable leaves in the laboratory at a spraying amount of 50 ml per pot of vegetables, ensuring that the leaves are completely wet but do not drip water.

[0022] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0023] The present invention utilizes a self - made composite silicon fertilizer added with pH - responsive pest - control microcapsules to achieve the effect of pest control.

[0024] First, the present invention uses nano - silica as the main body of the silicon fertilizer, forms composite particles with sodium bicarbonate and calcium citrate through spray - drying technology, and after mixing with self - made pH - responsive pest - control microcapsules, sprays them on the vegetable leaves. When pests feed, the acidic substances in the oral saliva react with sodium bicarbonate and calcium citrate, causing the local pH value to increase, which promotes the rupture of the pH - responsive pest - control microcapsules, quickly releases the active ingredients, directly acts on the pests' oral cavity and digestive tract, inhibits the pests' feeding and physiological activities. At the same time, the vegetables themselves activate the defense mechanism to achieve a precise response to the pests' feeding behavior. Moreover, the particles of the present invention can also induce the formation of silicified cells in vegetables to play a "mechanical fence" effect, increase the leaf hardness and tear - resistance strength. At the same time, the silicon fertilizer can also enhance the plant's stress resistance and promote plant growth; the spray - drying technology can control the size and shape of the particles, improving the uniformity and stability of the product.

[0025] Second, the self - made pH - responsive pest - control microcapsules in the present invention use oxidized paraffin as the main wall material of the microcapsules. After using the oil - in - water emulsion method to encapsulate the terpene compound and methyl jasmonate core materials, they are chemically cross - linked with a poly(lactic acid - maleic anhydride) copolymer under the action of a crosslinking agent to form pH - responsive pest - control microcapsules. These microcapsules can not only rupture and quickly release the core materials in a weakly alkaline environment but also slowly release the core materials during the daily process, achieving a long - term effect of pest control; the preparation of oxidized paraffin by bio - enzyme - catalyzed oxidation meets the requirements of green chemistry, is environmentally friendly and pollution - free. Oxidized paraffin has good chemical stability, can extend the storage period of the microcapsules, and has low cost; the poly(lactic acid - maleic anhydride) copolymer enhances the mechanical properties and thermal stability of the microcapsules through cross - linking, synergistically amplifies the pH - responsive signal, and precisely controls the release behavior. Moreover, maleic anhydride in the poly(lactic acid - maleic anhydride) copolymer exists in a polymerized form, and the hydrolyzed maleic acid is a natural organic acid, which is commonly present in fruits and meets the requirements of agricultural environmental protection. Detailed implementation manners

[0026] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] In order to more clearly illustrate the method provided by the present invention, the following embodiments are used for detailed description. The test methods for each index of the chemical fertilizer for pest-resistant vegetables prepared in the following embodiments are as follows:

[0028] Pest control performance test: Select 100 pots of the same type of vegetables in the growth period, divide them into 10 test groups, and evenly spray the chemical fertilizers prepared in Examples 1-3 and Comparative Examples 1-7 on the vegetable leaves at a spraying amount of 50 ml per pot of vegetables, and ensure that the leaves are completely wet but do not drip water. After spraying, release a certain amount of diamondback moths and aphids into the test groups, keep other conditions unchanged, and count the number of damaged leaves of diseased plants in each test group after 28 days.

[0029] Sustained-release performance test: Put 2 g of the chemical fertilizers prepared in Examples 1-3 and Comparative Examples 1-7 into non-woven bags respectively, place them in the soil with a depth of 5 cm and a relative humidity of 25%, and then take out the bags on the 1st, 7th, 14th, and 28th days respectively. After sampling, slowly rinse the soil adhering to the bag with water, dry it in an oven at 60 °C for 24 h and then weigh it. Calculate the release rate by the mass change of the fertilizer before and after weighing. Release rate = (mass before release - mass after release) / total mass.

[0030] Example 1

[0031] (1) Mix nano-silica with a particle size of 50 nm, sodium bicarbonate, calcium citrate and deionized water in a mass ratio of 6:1:1:50, stir at 1000 rpm for 30 min, and then pass through the conditions: the inlet temperature is 150 °C, the gas path pressure is 0.1 kg / cm, the pump speed is 10 ml / min, and the circulating wind speed is 0.6 m 3 / min and spray-dry to obtain composite particles with a particle size of 20 μm;

[0032] (2) Horseradish peroxidase was mixed with phosphate buffer to prepare an enzyme activation solution with a concentration of 1 mg / ml and a pH of 6. Paraffin in powder form with a particle size of 100 μm was mixed with the enzyme activation solution at a mass ratio of 1:0.1, stirred at 300 rpm for 10 min at 30 °C, and then an aqueous solution of 30 wt% H2O2 four times the mass of paraffin was added dropwise to the mixture at a rate of 2 ml / min. After maintaining stirring and reacting for 8 h, it was cooled to room temperature, petroleum ether 30 times the mass of paraffin was added, stirred at 100 rpm for 10 min, centrifuged at 4000 rpm for 10 min to remove the precipitate, the supernatant was distilled at 50 °C and a vacuum of -0.1 MPa for 1 h, and the solid was dried in an oven at 30 °C to constant weight to obtain oxidized paraffin;

[0033] (3) Polylactic acid with a molecular weight of 800 was dried in a drying oven at 60 °C for 12 h, and then added to a torque rheometer together with maleic anhydride at a mass ratio of 20:1. The temperature was set at 180 °C and the rotation speed was 60 rpm. After kneading for 2 min, diisopropylbenzene peroxide 0.001 times the mass of polylactic acid was added, and kneading continued for 8 min. After cooling to room temperature, solid particles were obtained. The solid particles were added to dichloromethane 10 times the mass of polylactic acid, stirred at 300 rpm for 10 min, placed in a water bath at 85 °C and refluxed until completely dissolved, precipitated in excess acetone and absolute ethanol respectively, and the dissolution-precipitation operation was repeated 3 times. The solid was then dried in a drying oven at 60 °C and a vacuum of 0.1 MPa to constant weight to obtain a polylactic acid-maleic anhydride polymer;

[0034] (4) Menthol, methyl jasmonate and ethanol were mixed at a mass ratio of 2:0.5:20 and stirred at 200 rpm for 10 min to obtain an oil-phase solution; oxidized paraffin was heated to 60 °C to melt it and then mixed with polysorbate 80, citric acid and deionized water at a mass ratio of 1:0.05:0.01:10, and stirred at 200 rpm for 30 min to form an aqueous-phase solution; the aqueous-phase solution was added to the oil-phase solution, emulsified at 2000 rpm for 30 min with an emulsifier to form an oil-in-water emulsion, and then a polylactic acid-maleic anhydride polymer 0.2 times the mass of oxidized paraffin was added. After stirring and reacting at 40 °C and 200 rpm for 4 h, the reaction solution was filtered by suction, the filter cake was washed twice with deionized water, and dried at 30 °C for 12 h to obtain pest-control microcapsules with a particle size of 400 μm;

[0035] (5) 20 parts by weight of composite particles, 20 parts by weight of pest-control microcapsules, 10 parts by weight of potassium dihydrogen phosphate and 10 parts by weight of urea were mixed, and then mixed with deionized water at a mass ratio of 1:50 at room temperature and stirred at 150 rpm for 10 min to form a chemical fertilizer for foliar spraying.

[0036] Example 2

[0037] (1) Mix nano-silica with a particle size of 80 nm, sodium bicarbonate, calcium citrate, and deionized water in a mass ratio of 7:2:1:50. After stirring at 1000 rpm for 30 min, spray drying is carried out under the conditions: inlet temperature of 150 °C, gas path pressure of 0.1 kg / cm, pump speed of 10 ml / min, and circulating air speed of 0.6 m 3 / min to obtain composite microparticles with a particle size of 35 μm;

[0038] (2) Mix horseradish peroxidase with phosphate buffer solution to prepare an enzyme activation solution with a concentration of 1 mg / ml and a pH of 6.5. Mix powdery paraffin with a particle size of 100 μm and the enzyme activation solution in a mass ratio of 1:0.2. After stirring at 35 °C and 300 rpm for 10 min, add 30 wt% H2O2 aqueous solution 5 times the mass of paraffin to the mixture dropwise at a rate of 2 ml / min. Keep stirring and reacting for 10 h, then cool to room temperature. Add petroleum ether 35 times the mass of paraffin, stir at 100 rpm for 10 min, and centrifuge at 4000 rpm for 10 min to remove the precipitate. Distill the supernatant at 55 °C and a vacuum degree of -0.1 MPa for 1.5 h, and then dry the solid in an oven at 30 °C to constant weight to obtain oxidized paraffin;

[0039] (3) Place polylactic acid with a molecular weight of 800 in a drying oven at 60 °C for 12 h, then add it to a torque rheometer together with maleic anhydride in a mass ratio of 20:1. Set the temperature to 180 °C and the rotation speed to 60 rpm. After kneading for 2 min, add diisopropylbenzene peroxide 0.001 times the mass of polylactic acid, and continue kneading for 8 min. After cooling to room temperature, obtain solid microparticles. Add the solid microparticles to dichloromethane 10 times the mass of polylactic acid and stir at 300 rpm for 10 min, then place it in a water bath at 85 °C and reflux until completely dissolved. Precipitate in excess acetone and absolute ethanol respectively, and repeat the dissolution-precipitation operation 3 times. Then dry the solid in a drying oven at 60 °C and a vacuum degree of 0.1 MPa to constant weight to obtain a polylactic acid-maleic anhydride polymer;

[0040] (4) Mix menthol, methyl jasmonate, and ethanol in a mass ratio of 3:0.1:20 and stir at 200 rpm for 10 min to obtain an oil-phase solution; Heat oxidized paraffin to 60 °C to melt it, then mix it with polysorbate 80, citric acid, and deionized water in a mass ratio of 1:0.1:0.02:10, and stir at 200 rpm for 30 min to form an aqueous solution; Add the aqueous solution to the oil-phase solution, emulsify it with an emulsifier at 2000 rpm for 30 min to form an oil-in-water emulsion, then add a polylactic acid-maleic anhydride polymer 0.25 times the mass of oxidized paraffin, stir and react at 40 °C and 200 rpm for 4 h, then filter the reaction solution, wash the filter cake with deionized water 3 times, and dry it at 30 °C for 12 h to obtain pest-control microcapsules with a particle size of 450 μm;

[0041] (5) Mix 25 parts by weight of the composite particles, 25 parts by weight of the pest control microcapsules, 12 parts by weight of potassium dihydrogen phosphate, and 12 parts by weight of urea, and then mix with deionized water at room temperature in a mass ratio of 1:50 and stir at 150 rpm for 10 min to form a chemical fertilizer for foliar spraying.

[0042] Example 3

[0043] (1) Mix nano-silica with a particle size of 100 nm, sodium bicarbonate, calcium citrate, and deionized water in a mass ratio of 8:3:1:50, stir at 1000 rpm for 30 min, and then spray-dry under the conditions of an inlet temperature of 150 °C, a gas path pressure of 0.1 kg / cm, a pump speed of 10 ml / min, and a circulating air speed of 0.6 m 3 / min to obtain composite particles with a particle size of 50 μm;

[0044] (2) Mix horseradish peroxidase with phosphate buffer to prepare an enzyme activation solution with a concentration of 1 mg / ml and a pH of 7; mix powdery paraffin with a particle size of 100 μm and the enzyme activation solution in a mass ratio of 1:0.3, stir at 40 °C at 300 rpm for 10 min, and then add a 30 wt% H2O2 aqueous solution 6 times the mass of paraffin to the mixture at a rate of 2 ml / min. Keep stirring and reacting for 12 h, cool to room temperature, add petroleum ether 40 times the mass of paraffin, stir at 100 rpm for 10 min, centrifuge at 4000 rpm for 10 min to remove the precipitate, distill the supernatant at 60 °C and a vacuum of -0.1 MPa for 2 h, and then dry the solid in an oven at 30 °C to constant weight to obtain oxidized paraffin;

[0045] (3) Place polylactic acid with a molecular weight of 800 in a drying oven at 60 °C for 12 h, add it to a torque rheometer together with maleic anhydride in a mass ratio of 20:1, set the temperature to 180 °C, the rotation speed to 60 rpm, knead for 2 min, add 0.001 times the mass of polylactic acid of diisopropylbenzene peroxide, continue kneading for 8 min, and cool to room temperature to obtain solid particles; add the solid particles to dichloromethane 10 times the mass of polylactic acid and stir at 300 rpm for 10 min, then place it in an 85 °C water bath and reflux until completely dissolved, precipitate in excess acetone and absolute ethanol respectively, repeat the dissolution-precipitation operation 3 times, and then dry the solid in a drying oven at 60 °C and a vacuum of 0.1 MPa to constant weight to obtain a polylactic acid-maleic anhydride polymer;

[0046] (4) Mix menthol, methyl jasmonate and ethanol in a mass ratio of 4:1.5:20, and stir at 200 rpm for 10 min to obtain an oil-phase solution; heat oxidized paraffin to 60 °C to melt it, and then mix it with polysorbate 80, citric acid and deionized water in a mass ratio of 1:0.15:0.03:10, and stir at 200 rpm for 30 min to form an aqueous-phase solution; add the aqueous-phase solution to the oil-phase solution, emulsify with an emulsifier at 2000 rpm for 30 min to form an oil-in-water emulsion, then add a polylactic acid-maleic anhydride polymer 0.3 times the mass of oxidized paraffin, and react at 40 °C and stir at 200 rpm for 4 h. Then, filter the reaction solution, wash the filter cake with deionized water 4 times, and dry at 30 °C for 12 h to obtain pest-control microcapsules with a particle size of 500 μm;

[0047] (5) Mix 30 parts by weight of composite microparticles, 30 parts by weight of pest-control microcapsules, 15 parts by weight of potassium dihydrogen phosphate, and 15 parts by weight of urea, and then mix with deionized water at room temperature in a mass ratio of 1:50 and stir at 150 rpm for 10 min to form a chemical fertilizer for foliar spraying.

[0048] Comparative Example 1

[0049] The difference between Comparative Example 1 and Example 2 is that step (1) is absent, and step (5) is changed to: mix 25 parts by weight of pest-control microcapsules, 12 parts by weight of potassium dihydrogen phosphate, and 12 parts by weight of urea, and then mix with deionized water at room temperature in a mass ratio of 1:50 and stir at 150 rpm for 10 min to form a chemical fertilizer for foliar spraying. The remaining steps are the same as those in Example 2.

[0050] Comparative Example 2

[0051] The difference between Comparative Example 2 and Example 2 lies in step (1). The difference is that step (1) is changed to: mix nano-silica with a particle size of 80 nm, calcium citrate and deionized water in a mass ratio of 7:1:50, and then stir at 1000 rpm for 30 min and spray-dry under the conditions of: inlet temperature of 150 °C, gas path pressure of 0.1 kg / cm, pump speed of 10 ml / min, and circulating wind speed of 0.6 m 3 / min to obtain composite microparticles with a particle size of 35 μm. The remaining steps are the same as those in Example 2.

[0052] Comparative Example 3

[0053] The difference between Comparative Example 3 and Example 2 lies in step (1). The difference is that step (1) is changed to: Mix nano-silica with a particle size of 80 nm, sodium bicarbonate, and deionized water in a mass ratio of 7:2:50, stir at 1000 rpm for 30 min, and then spray-dry under the conditions of an inlet temperature of 150 °C, a gas path pressure of 0.1 kg / cm, a pump speed of 10 ml / min, and a circulating air speed of 0.6 m 3 / min to obtain composite particles with a particle size of 35 μm. The remaining steps are the same as those in Example 2.

[0054] Comparative Example 4

[0055] The difference between Comparative Example 4 and Example 2 lies in step (4). The difference is that step (4) is changed to: Mix methyl jasmonate and ethanol in a mass ratio of 0.1:20 and stir at 200 rpm for 10 min to obtain an oil-phase solution; heat oxidized paraffin to 60 °C to melt it, then mix it with polysorbate 80, citric acid, and deionized water in a mass ratio of 1:0.1:0.02:10, and stir at 200 rpm for 30 min to form an aqueous-phase solution; add the aqueous-phase solution to the oil-phase solution, emulsify with an emulsifier at 2000 rpm for 30 min to form an oil-in-water emulsion, then add a polylactic acid-maleic anhydride polymer that is 0.25 times the mass of the oxidized paraffin, stir and react at 40 °C and 200 rpm for 4 h, filter the reaction solution, wash the filter cake with deionized water 3 times, and dry at 30 °C for 12 h to obtain pest-control microcapsules with a particle size of 450 μm. The remaining steps are the same as those in Example 2.

[0056] Comparative Example 5

[0057] The difference between Comparative Example 5 and Example 2 lies in step (4). The difference is that step (4) is changed to: Mix menthol and ethanol in a mass ratio of 3:20 and stir at 200 rpm for 10 min to obtain an oil-phase solution; heat oxidized paraffin to 60 °C to melt it, then mix it with polysorbate 80, citric acid, and deionized water in a mass ratio of 1:0.1:0.02:10, and stir at 200 rpm for 30 min to form an aqueous-phase solution; add the aqueous-phase solution to the oil-phase solution, emulsify with an emulsifier at 2000 rpm for 30 min to form an oil-in-water emulsion, then add a polylactic acid-maleic anhydride polymer that is 0.25 times the mass of the oxidized paraffin, stir and react at 40 °C and 200 rpm for 4 h, filter the reaction solution, wash the filter cake with deionized water 3 times, and dry at 30 °C for 12 h to obtain pest-control microcapsules with a particle size of 450 μm. The remaining steps are the same as those in Example 2.

[0058] Comparative Example 6

[0059] The difference between Comparative Example 6 and Example 2 is that steps (2), (3), and (4) are absent. Step (5) is changed to: Mix 25 parts by weight of composite microparticles, 12 parts by weight of potassium dihydrogen phosphate, and 12 parts by weight of urea, and then mix with deionized water at room temperature in a mass ratio of 1:50 and stir at 150 rpm for 10 min to form a chemical fertilizer for foliar spraying. The remaining steps are the same as those in Example 2.

[0060] Comparative Example 7

[0061] The difference between Comparative Example 7 and Example 2 is that steps (1), (2), (3), and (4) are absent. Step (5) is changed to: Mix 12 parts by weight of potassium dihydrogen phosphate and 12 parts by weight of urea, and then mix with deionized water at room temperature in a mass ratio of 1:50 and stir at 150 rpm for 10 min to form a chemical fertilizer for foliar spraying.

[0062] Effect Example

[0063] The performance analysis results of the chemical fertilizers for pest - control vegetables using Examples 1 to 3 and Comparative Examples 1 to 7 of the present invention are given in Table 1 below.

[0064] Table 1

[0065]

[0066]

[0067] From the comparison of the experimental data on the number of leaf damages between the examples and the comparative examples, it can be found that the present invention uses nano - silica as the main body of the silicon fertilizer, forms composite microparticles with sodium bicarbonate and calcium citrate through spray - drying technology, and after mixing with self - made pH - responsive pest - control microcapsules and spraying on the vegetable leaves, when pests feed, the acidic substances in the oral saliva react with sodium bicarbonate and calcium citrate, causing the local pH value to increase, which prompts the pH - responsive pest - control microcapsules to rupture, quickly release the active ingredients, directly act on the pests' oral cavity and digestive tract, inhibit the pests' feeding and physiological activities, and at the same time the vegetables themselves activate the defense mechanism to achieve a precise response to the pests' feeding behavior; from the comparison of the experimental data on the release rate between the examples and the comparative examples, it can be found that the self - made pH - responsive pest - control microcapsules in the present invention can not only rupture and quickly release the core material in a weakly alkaline environment, but also slowly release the core material during the daily process, achieving the effect of long - term pest control.

[0068] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claim concerned.

Claims

1. A preparation method of chemical fertilizer for pest - resistant vegetables, characterized in that, It includes 20 - 30 parts by weight of composite particles, 20 - 30 parts by weight of pest - control microcapsules, 10 - 15 parts by weight of potassium dihydrogen phosphate and 10 - 15 parts by weight of urea; The preparation method of the composite particles is as follows: Mix nano - silica, sodium bicarbonate, calcium citrate and deionized water according to a mass ratio of 6 - 8:1 - 3:1:50, stir at 1000 rpm for 30 min, and then obtain composite particles with a particle size of 20 - 50 μm through spray - drying; The preparation method of the pest - control microcapsules is as follows: (1) Mix the bio - enzyme and buffer solution to prepare an enzyme activation solution with a concentration of 1 mg / ml and a pH of 6 - 7; Mix the powdery paraffin and the enzyme activation solution according to a mass ratio of 1:0.1 - 0.3, stir at 30 - 40 °C and 300 rpm for 10 min, then add an oxidant with a mass 4 - 6 times that of the paraffin to the mixed solution at a rate of 2 ml / min, keep stirring and reacting for 8 - 12 h, cool to room temperature, add an organic solvent with a mass 30 - 40 times that of the paraffin, stir at 100 rpm for 10 min, centrifuge at 4000 rpm for 10 min, distill the supernatant at 50 - 60 °C and a vacuum degree of - 0.1 MPa for 1 - 2 h, and then dry the solid in an oven at 30 °C for 12 h to obtain oxidized paraffin; (2) Mix the terpene compound, methyl jasmonate and ethanol according to a mass ratio of 2 - 4:0.5 - 1.5:20, and stir at 200 rpm for 10 min to obtain an oil - phase solution; Heat the oxidized paraffin to 60 °C to melt it, and then mix it with a surfactant, a cross - linker and deionized water according to a mass ratio of 1:0.05 - 0.15:0.01 - 0.03:10, and stir at 200 rpm for 30 min to form an aqueous - phase solution; Add the aqueous - phase solution to the oil - phase solution, emulsify with an emulsifier at 2000 rpm for 30 min to form an oil - in - water emulsion, then add a polylactic acid - maleic anhydride polymer with a mass 0.2 - 0.3 times that of the oxidized paraffin, stir and react at 40 °C and 200 rpm for 4 h, filter the reaction solution, wash the filter cake with deionized water 2 - 4 times, and dry at 30 °C for 12 h to obtain pest - control microcapsules with a particle size of 400 - 500 μm.

2. The preparation method of a chemical fertilizer for pest-resistant vegetables according to claim 1, characterized in that, The nano - silica in step (1) is: with a particle size of 50 - 100 nm.

3. The preparation method of a chemical fertilizer for pest - resistant vegetables according to claim 1, characterized in that, The bio - enzyme in step (2) is: horseradish peroxidase.

4. The preparation method of a chemical fertilizer for pest-resistant vegetables according to claim 1, characterized in that, The buffer solution in step (2) is: phosphate buffer solution.

5. The preparation method of a chemical fertilizer for pest - resistant vegetables according to claim 1, characterized in that, The oxidant in step (2) is: 30 wt% H2O2 aqueous solution.

6. The preparation method of a chemical fertilizer for pest - resistant vegetables according to claim 1, characterized in that, The organic solvent in step (2) is: petroleum ether.

7. The preparation method of a chemical fertilizer for pest-resistant vegetables according to claim 1, characterized in that, The terpene compound in step (3) is: at least one of menthol, limonene, artemisinin, toosendanin and azadirachtin.

8. The preparation method of a chemical fertilizer for pest - resistant vegetables according to claim 1, characterized in that, The surfactant in step (3) is: polysorbate 80.

9. The preparation method of a chemical fertilizer for pest - resistant vegetables according to claim 1, characterized in that, The cross - linker in step (3) is: citric acid.

10. Application of a chemical fertilizer for pest - resistant vegetables, characterized in that, Mix the chemical fertilizer and deionized water according to a mass ratio of 1:50, stir at 150 rpm for 10 min at room temperature to form a spraying solution, and uniformly spray 50 ml per pot of vegetables on the vegetable leaves in the laboratory, ensuring that the leaves are completely wet but do not drip water.

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