Disease-preventing and insect-repelling water-soluble fertilizer and preparation process thereof

Abstract

The application relates to a disease-preventing and insect-repelling water-soluble fertilizer and a preparation process thereof, and belongs to the technical field of fertilizers. The water-soluble fertilizer is prepared from the following raw materials in parts by weight: water 1000-1500 parts, potassium chloride 80-120 parts, potassium dihydrogen phosphate 150-200 parts, urea ammonium nitrate solution 300-400 parts, urea 150-200 parts, citric acid 3-8 parts, humic acid substances 130-170 parts, EDTA-2Na 3-8 parts, zinc sulfate monohydrate 1-3 parts, boron source 1-3 parts, manganese sulfate monohydrate 0.3-1.0 parts, modified lignin sulfonate synergistic liquid 1-3 parts and 20-30 parts of a pH regulator; the prepared water-soluble fertilizer has excellent disease-preventing and insect-repelling effects.

Description

Technical Field

[0001] This invention belongs to the field of fertilizer technology and relates to a water-soluble fertilizer for disease prevention and pest control and its preparation process. Background Technology

[0002] Water-soluble fertilizers, as a type of multi-element compound fertilizer that can be completely dissolved in water, have advantages such as high nutrient content, good absorption and utilization rate, and can be applied with water. They are widely used in water-saving irrigation agriculture such as drip irrigation and sprinkler irrigation, as well as in facility agriculture. Among them, humic acid substances have become important functional components in water-soluble fertilizers because of their effects on soil improvement, crop growth promotion, and enhanced crop resistance.

[0003] However, existing humic acid-containing water-soluble fertilizers have the following shortcomings: First, humic acid substances are unstable in aqueous solutions, especially when added at high concentrations, and are prone to flocculation and precipitation, which limits the effective content and application effect of humic acid water-soluble fertilizers; second, the disease prevention and pest control functions of humic acid rely on indirect regulation and lack active control capabilities.

[0004] Therefore, there is an urgent need to develop a water-soluble fertilizer with high humic acid content, long-term storage stability, and active disease and insect prevention functions, as well as its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a water-soluble fertilizer for disease prevention and insect repellency and its preparation process. The prepared water-soluble fertilizer has excellent disease prevention and insect repellency effects.

[0006] The objective of this invention can be achieved through the following technical solutions: A water-soluble fertilizer for disease prevention and pest control, wherein the water-soluble fertilizer is composed of the following raw materials in parts by weight: Water 1000-1500 parts, potassium chloride 80-120 parts, potassium dihydrogen phosphate 150-200 parts, urea ammonium nitrate solution 300-400 parts, urea 150-200 parts, citric acid 3-8 parts, humic acid 130-170 parts, EDTA-2Na 3-8 parts, zinc sulfate monohydrate 1-3 parts, boron source 1-3 parts, manganese sulfate monohydrate 0.3-1.0 parts, modified lignin sulfonate synergist 1-3 parts, pH adjuster 20-30 parts; The humic acid substance is a mixture of potassium humate and potassium fulvate in a mass ratio of 1:(60~80), and is treated with hydroxymethylated lignin and epichlorohydrin.

[0007] The water-soluble fertilizer prepared by this invention contains macroelements (potassium chloride, potassium dihydrogen phosphate, urea, ammonium nitrate, urea), microelements (zinc sulfate, boron source, manganese sulfate), chelating agents (citric acid, EDTA-2Na), and humic acid substances. This invention utilizes a double chelation system of citric acid and EDTA-2Na to ensure that microelements such as zinc, manganese, and boron remain stably dissolved in their ionic state under conditions where macroelements coexist. The product is clear and transparent, suitable for precision irrigation systems such as drip irrigation and sprinkler irrigation.

[0008] This invention unexpectedly discovered that pretreatment of humic acid substances with hydroxymethylated lignin and epichlorohydrin can overcome the flocculation bottleneck under high potassium humate content, allowing them to remain stable in a water-soluble state for ≥30 days even when the total humic acid content is as high as 130-170 parts. After modification, high-content humic acid substances not only retain traditional soil-improving and root-promoting functions, but also, through the structural characteristics of the lignin-humic acid cross-linking network, enable the fertilizer to have a physical inhibitory effect on soil-borne pathogens and a slow-release nutrient function. When combined with modified lignin sulfonate synergistic solution, a synergistic disease-resistant and insect-repellent effect is produced.

[0009] As a preferred embodiment of the present invention, the treatment process for the humic acid substances is as follows: S1. Mix hydroxymethylated lignin and humic acid substances at a mass ratio of 1:(1~3), add deionized water, adjust the pH to 8.0~9.5 with potassium hydroxide, and stir for 1~3 hours at 50~70℃. S2. Add epichlorohydrin and continue stirring at 60-80℃ for 2-5 hours; S3. Spray dry the complex emulsion.

[0010] In this invention, humic acid substances are obtained by mixing potassium humate and potassium fulvate in a mass ratio of 1:(60~80). Under this ratio, the water solubility and bioactivity advantages of potassium fulvate are fully utilized. Although the amount of potassium humate is very small, the aromatic ring hydrophobic skeleton retained in its molecule can form local ordered aggregates with the aliphatic side chains of potassium fulvate through hydrophobic interactions. As hydrophobic microregions in the physical cross-linking network, they work synergistically with hydrogen bonds to enhance the overall cohesion of the cross-linking network. The two work together to achieve a unity of high water solubility, high bioactivity and high stability.

[0011] The process employs a stepwise approach, first physical interaction (hydrogen bonding) and then chemical cross-linking (epoxychloropropane). Under alkaline conditions of pH 8.0–9.5, the carboxyl groups of humic acid molecules fully ionize into carboxylate groups, which form stronger hydrogen bonds with the hydroxyl groups of hydroxymethylated lignin, creating a physical cross-linking network. This network helps to form a uniformly distributed chemical cross-linking network, ultimately resulting in a three-dimensional interpenetrating network structure where the physical and chemical networks interweave.

[0012] Finally, the microcapsule powder obtained by spray drying has good water dispersibility and redissolution, and can be directly added to clear liquid water-soluble fertilizer without additional grinding or dispersion treatment.

[0013] As a preferred embodiment of the present invention, the preparation process of the modified lignin sulfonate synergistic solution is as follows: By weight, mix 80-150 parts of lignin sulfonate, 5-20 parts of citric acid, 0.5-3 parts of copper sulfate with 500-1000 parts of deionized water; Subsequently, the mixture was transferred to a high-pressure reactor and reacted at 170-185°C for 45-100 minutes. After the reaction was completed, it was cooled to 60-90°C, and hydrogen peroxide at 5-20% of the mass of lignin sulfonate was added. The reactor was then sealed again and heated to 180-85°C, and the reaction was continued for 120-150 minutes. Finally, it was cooled to 40-60°C and filtered to obtain the modified lignin sulfonate synergistic solution.

[0014] In this process, acid hydrolysis, Cu 2+ Lignosulfonate is broken down into smaller molecular fragments under catalysis, and then oxidized with a strong oxidant. Active oxygen-containing functional groups such as carboxyl and carbonyl groups are introduced onto these smaller fragments. This two-step synergistic process significantly enhances the bioactivity and complexing ability of the modified product. The modified ligninsulfonate synergistic solution exhibits stronger hydrophilicity and dispersibility; only 1-3 parts are needed to significantly improve the anti-flocculation performance of water-soluble fertilizers and crop absorption rates.

[0015] As a preferred embodiment of the present invention, the boron source is either boric acid or borax.

[0016] Boric acid and borax are both common industrial boron sources. They are water-soluble, low-cost, and have stable sources. Their solubility is not affected in the citric acid-EDTA double chelation system, and they can exist stably in fertilizers for a long time.

[0017] As a preferred embodiment of the present invention, the pH adjuster is sodium hydroxide, so that the pH value of the water-soluble fertilizer is 5.5~6.5.

[0018] Within the pH range of 5.5–6.5, EDTA and citric acid have a positive effect on Zn 2+ Mn 2+ The chelation stability constant is in the highest value range, making it difficult for metal ions to hydrolyze and precipitate; it can also ensure that the carboxyl group of humic acid is partially ionized without being too alkaline and causing excessive dissolution and degradation of humic acid; the pH is close to the optimal pH range of the rhizosphere for most crops, and does not disrupt the soil acid-base balance after application.

[0019] As a preferred embodiment of the present invention, the urea ammonium nitrate solution contains 28-32% N.

[0020] Urea ammonium nitrate solution with 28-32% N content has good fluidity, rich nitrogen forms (including nitrate nitrogen, ammonium nitrogen, and amide nitrogen), combines rapid and slow effects, and has the best compatibility with other components of the formula.

[0021] As a preferred embodiment of the present invention, in step S1, the total solids concentration of the hydroxymethylated modified lignin and humic acid substances is 5-15%.

[0022] As a preferred embodiment of the present invention, in step S2, the epichlorohydrin is 1-5% of the total solids of hydroxymethylated modified lignin and humic acid substances.

[0023] Adding 1-5% epichlorohydrin can achieve a moderate chemical cross-linking density, avoiding a loose network structure and insufficient encapsulation efficiency caused by too low a degree of cross-linking; it also avoids an overly dense network and slow nutrient release caused by too high a degree of cross-linking.

[0024] As a preferred embodiment of the present invention, the spray drying conditions are as follows: inlet air temperature 160~200℃, outlet air temperature 80~110℃, feed temperature 40~60℃, feed rate 50~200mL / min, and spray pressure 0.2~0.6MPa.

[0025] By controlling the inlet and outlet air temperatures, the thermal degradation of the active functional groups of humic acid is avoided while ensuring rapid evaporation of moisture, and the functional group retention rate is ≥90%.

[0026] A method for preparing a water-soluble fertilizer for disease prevention and insect repellency, comprising the following steps: According to the formula, citric acid and EDTA-2Na are dissolved in part of the water, heated to 45~60℃, and stirred until completely dissolved. Then, zinc sulfate monohydrate, boron source and manganese sulfate monohydrate are added in sequence, and stirring is continued for 20~40 minutes to obtain the chelation solution. Add humic acid substances to the remaining water, stir at 50~70℃ and keep warm for 30 minutes to obtain an organic activated solution; Add potassium chloride, potassium dihydrogen phosphate, urea ammonium nitrate solution and urea to organic activating liquid, stir at 40~60℃ until completely dissolved to obtain basic fertilizer solution; Add the chelating solution and the modified lignin sulfonate synergistic solution to the base fertilizer solution, add the remaining water, add pH adjustment solution, continue stirring for 20 minutes, and cool to room temperature to obtain the water-soluble fertilizer.

[0027] This invention utilizes metal ions (Zn) 2+ Mn 2+The organic matter (humic acid) is pre-chelated with citric acid / EDTA-2Na, then the organic matter (humic acid) is activated separately, and finally compounded in a macro-element solution. This step-by-step operation can avoid the risk of precipitation caused by direct contact between metal ions and humic acid and phosphate.

[0028] The organic activation solution is kept at 50-70℃ for 30 minutes, which can fully activate the active groups of humic acid while avoiding the damage to the molecular structure of humic acid caused by high temperature (>80℃). Adding the modified lignin sulfonate synergist solution after the basic fertilizer solution has formed a stable chelation-dispersion system can prevent premature contact and pre-reaction between the active components in the synergist solution and metal ions and humic acid, ensuring the long-term storage stability of the final water-soluble fertilizer and guaranteeing the full utilization of the functions of each fertilizer component.

[0029] After all components are compounded, a final pH adjustment (to 5.5~6.5) is performed to ensure that each component is introduced into the system under optimal conditions, avoiding the situation where some components are exposed to an unfavorable pH environment due to pH adjustment before feeding.

[0030] The beneficial effects of this invention are: (1) The present invention prepares a fertilizer with high humic acid content. By pretreating humic acid substances with hydroxymethylated lignin and epichlorohydrin, the problem of easy flocculation of potassium humate at high content is improved. The prepared fertilizer can maintain a stable water-soluble state for ≥30 days.

[0031] (2) The present invention adopts a two-step synergistic modification process of "acid hydrolysis and oxidation" for lignin sulfonate, so that the modified lignin sulfonate synergistic liquid has excellent anti-flocculation and dispersion function, metal ion complexation function and biostimulation function, and only 1 to 3 parts of the addition amount can significantly improve the storage stability of water-soluble fertilizer and crop absorption rate.

[0032] (3) The present invention uses a five-step preparation process of metal pre-chelation, organic matter activation, basic fertilizer solution preparation, functional component addition and pH precise final adjustment. Each step works together to ensure that the product is clear and transparent and remains highly stable in hard water environment. The prepared water-soluble fertilizer has excellent disease prevention and insect repellent effects. Detailed Implementation

[0033] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0034] It should be noted that, unless otherwise specified, the present invention does not specifically limit the source of the raw materials used in the following embodiments. Commercially available products or products prepared by conventional preparation methods that are well known to those skilled in the art can be used. Experimental methods that do not specify specific conditions are all conventional methods and conventional conditions well known in the art.

[0035] Preparation of hydroxymethylated lignin: Lignin, sodium hydroxide aqueous solution (pH=11), and 37% formaldehyde solution were mixed in a ratio of 1g:10mL:1g and stirred in an 80℃ water bath for 3 hours. After the reaction was completed, the pH was adjusted to 2.5 with dilute hydrochloric acid, and hydroxymethylated lignin was precipitated. The precipitated lignin was filtered, washed with deionized water until neutral, and dried under vacuum at 50℃ for 24 hours to obtain hydroxymethylated lignin.

[0036] Example 1

[0037] The treatment process for humic acid substances is as follows: S1. A mixture of potassium humate and potassium fulvate at a mass ratio of 1:70 yields humic acid substances. Hydroxymethylated lignin is then mixed with the humic acid substances at a mass ratio of 1:2. Deionized water is added, and the pH is adjusted to 8.5 with potassium hydroxide. The mixture is stirred at 60°C for 2 hours. The total solids concentration of the hydroxymethylated modified lignin and humic acid substances is 10%. S2. Add epichlorohydrin and continue stirring at 70°C for 3 hours. The amount of epichlorohydrin is 1-5% of the total solids of hydroxymethylated lignin and humic acid substances. S3. Spray dry the complex emulsion with an inlet air temperature of 180℃, an outlet air temperature of 90℃, a feed temperature of 50℃, a feed rate of 120mL / min, and a spray pressure of 0.4MPa.

[0038] Preparation of modified lignin sulfonate synergistic solution: By weight, mix 100 parts lignin sulfonate, 15 parts citric acid, 2 parts copper sulfate and 800 parts deionized water; Subsequently, the mixture was transferred to a high-pressure reactor and reacted at 175°C for 60 minutes. After the reaction was completed, it was cooled to 70°C, and hydrogen peroxide at 10% of the mass of lignin sulfonate was added. The reactor was then sealed again and heated to 182°C, and the reaction was continued for 130 minutes. Finally, it was cooled to 50°C and filtered to obtain the modified lignin sulfonate synergistic solution.

[0039] Preparation of water-soluble fertilizers for disease prevention and pest control: Dissolve 5 parts citric acid and 5 parts EDTA-2Na in 400 parts water by weight, heat to 50°C, stir until completely dissolved, then add 2 parts zinc sulfate monohydrate, 2 parts boric acid and 0.6 parts manganese sulfate monohydrate in sequence, and continue stirring for 30 minutes to obtain a chelation solution. Add 150 parts of humic acid to the remaining water, stir at 60°C and keep warm for 30 minutes to obtain an organic activated solution; Add 100 parts potassium chloride, 170 parts potassium dihydrogen phosphate, 350 parts urea ammonium nitrate solution (containing 30% N) and urea to 180 parts organic activating liquid, and stir at 50°C until completely dissolved to obtain the basic fertilizer solution; Add the chelating solution and 2 parts of modified lignin sulfonate synergistic solution to the base fertilizer solution, then add 900 parts of water with 26 parts of sodium hydroxide solution, continue stirring for 20 minutes, and cool to room temperature to obtain water-soluble fertilizer.

[0040] Example 2

[0041] This example is basically the same as Example 1, except that the water-soluble fertilizer in this example is composed of the following raw materials in parts by weight: 1000 parts water, 80 parts potassium chloride, 150 parts potassium dihydrogen phosphate, 300 parts urea ammonium nitrate solution, 150 parts urea, 3 parts citric acid, 130 parts humic acid, 3 parts EDTA-2Na, 1 part zinc sulfate monohydrate, 1 part boric acid, 0.3 parts manganese sulfate monohydrate, 1 part modified lignin sulfonate synergist, and 20 parts pH adjuster.

[0042] Example 3

[0043] This example is basically the same as Example 1, except that the water-soluble fertilizer in this example is composed of the following raw materials in parts by weight: 1500 parts water, 120 parts potassium chloride, 200 parts potassium dihydrogen phosphate, 400 parts urea ammonium nitrate solution, 200 parts urea, 8 parts citric acid, 170 parts humic acid, 8 parts EDTA-2Na, 3 parts zinc sulfate monohydrate, 3 parts boric acid, 1.0 part manganese sulfate monohydrate, 3 parts modified lignin sulfonate synergist, and 30 parts pH adjuster.

[0044] Example 4

[0045] It is basically the same as Example 1, except that the ratio of potassium humate to potassium fulvate in this example is 1:30.

[0046] Example 5

[0047] It is basically the same as Example 1, except that the ratio of potassium humate to potassium fulvate in this example is 1:100.

[0048] Comparative Example 1 This is basically the same as Example 1, except that the humic acid substances in this comparative example are not pretreated with hydroxymethylated lignin and epichlorohydrin, but are directly added to the formulation after physical mixing of KOM and potassium fulvate in the same ratio (1:70).

[0049] Comparative Example 2 This is basically the same as Example 1, except that no modified lignin sulfonate synergist is added in this comparative example.

[0050] Comparative Example 3 This is basically the same as Example 1, except that the lignin sulfonate in this comparative example is not treated in any way, and 100 parts of lignin sulfonate are mixed with 800 parts of deionized water to make a lignin sulfonate synergist.

[0051] Comparative Example 4 This example is essentially the same as Example 1, except that the treatment process for humic acid substances in this comparative example is as follows: Potassium humate and potassium fulvate were mixed at a mass ratio of 1:70 to obtain humic acid substances. These substances were then mixed with hydroxymethylated lignin, humic acid substances, epichlorohydrin, and water. The mixture was stirred and reacted at 70°C for 5.5 hours. The amount of epichlorohydrin was 1-5% of the total solids of the hydroxymethylated lignin and humic acid substances. The mass ratio of hydroxymethylated lignin to humic acid substances was 1:2, and the total solids concentration of the hydroxymethylated lignin and humic acid substances was 10%. The complex emulsion was then spray-dried at an inlet air temperature of 180°C, an outlet air temperature of 90°C, a feed temperature of 50°C, a feed rate of 120 mL / min, and a spray pressure of 0.4 MPa.

[0052] Comparative Example 5 This is basically the same as Example 1, except that citric acid is not added in this comparative example, and EDTA-2Na is used directly as a single chelating agent.

[0053] Comparative Example 6 This is basically the same as Example 1, except that potassium humate is not added in this comparative example, and the only humic substance is potassium fulvate.

[0054] Comparative Example 7 This is basically the same as Example 1, except that ordinary lignin is used in the treatment of humic acid substances in this comparative example.

[0055] Performance testing 1. Insect repellent and disease prevention effects: A pot experiment was conducted using tomatoes as the experimental subject. The experiment included 12 treatment groups (Examples 1-5 and Comparative Examples 1-7), with three replicates per group. One tomato seedling was planted in each pot. Each treatment group was irrigated with a fertilizer diluted 250 times, applied every 7 days for four consecutive applications. After the experiment, tomato plant height, stem diameter, and number of fruits per plant were measured. The results are shown in Table 1 below. Table 1

[0056] Based on the above data, it can be seen that the root-knot nematode infection rate of Examples 1-3 is ≤5%, and the crop height, stem diameter, and number of fruits per plant are all at excellent levels, indicating that the fertilizer of the present invention can effectively promote crop growth while maintaining insect and disease prevention effects.

[0057] Furthermore, when the proportion of humic acid is too high or too low, the growth-promoting and disease-preventing effects decrease. This indicates that when the ratio of potassium humate to potassium fulvate deviates from the range of 1:60~80, the cross-linked network structure is incomplete, and the disease-preventing and insect-repelling functions are impaired. Therefore, the insect-repelling and disease-preventing effects of Examples 4 and 5 both decrease.

[0058] In Comparative Example 1, humic acid was not pretreated, thus it could not exert the cross-linking effect of hydroxymethylated lignin and epichlorohydrin, resulting in an infection rate of 16%.

[0059] In Comparative Example 2, no modified lignin sulfonate synergist was added. In Comparative Example 3, lignin sulfonate was added directly without treatment. The plant height was 60.2 cm and the infection rate was 11%. Although Comparative Example 3 was worse than Example 1, it was better than Comparative Example 1. This indicates that untreated lignin sulfonate still has some dispersing function.

[0060] Comparative Example 4, which used a one-step cross-linking method, had a plant height of 58.8 cm and an infection rate of 12%, which was worse than the step-by-step modification treatment. The root-knot nematode infection rate was 12%, and the plant height was 58.8 cm, which was inferior to Example 1.

[0061] In Comparative Example 5, without the addition of citric acid and using only EDTA-2Na as a single chelating agent, the root-knot nematode infection rate was 11%, and the plant height was 61.8 cm. This indicates that the addition of citric acid not only affects the solubility of trace elements, but also indirectly affects the disease resistance of crops by maintaining the effective form of metal ions.

[0062] In Comparative Example 6, no potassium humate was added, and the only humic substance was potassium fulvate. The plant height was 63.0 cm and the infection rate was 10%. This shows that even if only potassium fulvate is added or no potassium humate is added, the plant can still maintain a certain stability under the premise that the total amount of humic substances remains unchanged. However, it is worse than Example 1.

[0063] In Comparative Example 7, when ordinary lignin was used instead of hydroxymethylated lignin, the root-knot nematode infection rate was 14%, and the plant height was 58.0 cm, significantly worse than in Example 1. The lack of hydroxymethyl active groups in ordinary lignin molecules further demonstrates the necessity of lignin hydroxymethylation modification.

[0064] 2. Fertilizer stability: Prepare standard hardness water (Ca 2+ Concentration 200 mg / L, Mg 2+The fertilizer samples from Examples 1-5 and Comparative Examples 1-7 were diluted 250 times with standard hardness water (concentration 100 mg / L). After standing for 24 hours, the solution state was observed, and the humic acid flocculation precipitation amount (volume fraction of precipitate after centrifugation at 4000 rpm for 10 min) was determined. The results are shown in Table 2 below. Table 2

[0065] The results above show that Examples 1-3, after dilution in a hard water environment, only exhibited a uniform, slightly turbid state with a precipitate volume fraction ≤0.6%, demonstrating excellent resistance to hard water flocculation. Examples 4 and 5 were worse than Example 1, indicating that a specific ratio of potassium humate to potassium fulvicate (1:60~80) can maintain the stability of high humic acid content.

[0066] The precipitate volume fractions of Comparative Examples 1-7 were significantly higher than those of the Example, with Comparative Examples 5, 3, 7, and 1 showing the worst results. This is because the humic acid and lignin sulfonate were not treated in these comparative examples, and the chelating effect of citric acid was lacking. The results indicate that this invention, through the synergistic effect of humic acid double crosslinking pretreatment, specific ratio compounding, citric acid-EDTA double chelation system, and modified lignin sulfonate synergistic solution, can effectively solve the problem of easy flocculation and precipitation of humic acid water-soluble fertilizers in hard water environments.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A water-soluble fertilizer for disease prevention and insect repellent, characterized in that, The water-soluble fertilizer is composed of the following raw materials in parts by weight: Water 1000-1500 parts, potassium chloride 80-120 parts, potassium dihydrogen phosphate 150-200 parts, urea ammonium nitrate solution 300-400 parts, urea 150-200 parts, citric acid 3-8 parts, humic acid 130-170 parts, EDTA-2Na 3-8 parts, zinc sulfate monohydrate 1-3 parts, boron source 1-3 parts, manganese sulfate monohydrate 0.3-1.0 parts, modified lignin sulfonate synergist 1-3 parts, pH adjuster 20-30 parts; The humic acid substance is a mixture of potassium humate and potassium fulvate in a mass ratio of 1:(60~80), and is treated with hydroxymethylated lignin and epichlorohydrin.

2. The water-soluble fertilizer for disease prevention and insect repellency according to claim 1, characterized in that, The treatment process for the humic acid substances is as follows: S1. Mix hydroxymethylated lignin and humic acid substances at a mass ratio of 1:(1~3), add deionized water, adjust the pH to 8.0~9.5 with potassium hydroxide, and stir for 1~3 hours at 50~70℃. S2. Add epichlorohydrin and continue stirring at 60-80℃ for 2-5 hours; S3. Spray dry the complex emulsion.

3. The water-soluble fertilizer for disease prevention and insect repellency according to claim 1, characterized in that, The preparation process of the modified lignin sulfonate synergist is as follows: By weight, mix 80-150 parts of lignin sulfonate, 5-20 parts of citric acid, 0.5-3 parts of copper sulfate with 500-1000 parts of deionized water; Subsequently, the mixture was transferred to a high-pressure reactor and reacted at 170-185°C for 45-100 minutes. After the reaction was completed, it was cooled to 60-90°C, and hydrogen peroxide at 5-20% of the mass of lignin sulfonate was added. The reactor was then sealed again and heated to 180-85°C, and the reaction was continued for 120-150 minutes. Finally, it was cooled to 40-60°C and filtered to obtain the modified lignin sulfonate synergistic solution.

4. The water-soluble fertilizer for disease prevention and insect repellency according to claim 1, characterized in that, The boron source is either boric acid or borax.

5. The water-soluble fertilizer for disease prevention and insect repellency according to claim 1, characterized in that, The pH adjuster is sodium hydroxide, which makes the pH value of the water-soluble fertilizer 5.5~6.

5.

6. The water-soluble fertilizer for disease prevention and insect repellency according to claim 1, characterized in that, The urea ammonium nitrate solution contains 28-32% N.

7. The water-soluble fertilizer for disease prevention and insect repellency according to claim 2, characterized in that, In step S1, the total solids concentration of the hydroxymethylated modified lignin and humic acid substances is 5-15%.

8. The water-soluble fertilizer for disease prevention and insect repellency according to claim 2, characterized in that, In step S2, the epichlorohydrin is 1-5% of the total solids of hydroxymethylated lignin and humic acid substances.

9. The water-soluble fertilizer for disease prevention and insect repellency according to claim 1, characterized in that, The spray drying conditions are as follows: inlet air temperature 160~200℃, outlet air temperature 80~110℃, feed temperature 40~60℃, feed rate 50~200mL / min, and spray pressure 0.2~0.6MPa.

10. A method for preparing a water-soluble fertilizer for disease prevention and insect repellency as described in any one of claims 1-9, characterized in that, The steps are as follows: According to the formula, citric acid and EDTA-2Na are dissolved in part of the water, heated to 45~60℃, and stirred until completely dissolved. Then, zinc sulfate monohydrate, boron source and manganese sulfate monohydrate are added in sequence, and stirring is continued for 20~40 minutes to obtain the chelation solution. Add humic acid substances to the remaining water, stir at 50~70℃ and keep warm for 30 minutes to obtain an organic activated solution; Add potassium chloride, potassium dihydrogen phosphate, urea ammonium nitrate solution and urea to organic activating liquid, stir at 40~60℃ until completely dissolved to obtain basic fertilizer solution; Add the chelating solution and the modified lignin sulfonate synergistic solution to the base fertilizer solution, add the remaining water, add pH adjustment solution, continue stirring for 20 minutes, and cool to room temperature to obtain the water-soluble fertilizer.

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