Multifunctional water-soluble fertilizer based on biological stimulant and preparation method thereof

Abstract

The application discloses a kind of multifunctional water-soluble fertilizer based on biological stimulant and preparation method thereof, multifunctional water-soluble fertilizer includes the following components by weight parts: organic fertilizer extract 30-45 parts, biological stimulant suspension 10-20 parts;Calcium nitrate 6-10 parts, potassium nitrate 4-8 parts, potassium dihydrogen phosphate 3-6 parts, EDTA chelated zinc 0.2-0.5 parts, EDTA chelated magnesium 0.1-0.4 parts, deionized water 25-35 parts, dispersing agent 1-3 parts;The biological stimulant suspension includes the following components by weight parts: biological stimulant 0.05-0.4 parts, sodium alginate 1.0-2.0 parts, emulsifier 0.1-0.6 parts, potassium fulvic acid of mineral source 2.0-3.0 parts, chitosan hydrochloride 1.5-2.5 parts, sodium tripolyphosphate 0.5-1.0 parts, anhydrous ethanol 1-20 parts.The application replaces traditional strong acid strong alkali high-temperature hydrolysis by ladder directional enzymolysis process, can retain the original heat-sensitive biological active substance in organic fertilizer to the greatest extent, solves the problem that traditional process leads to biological stimulation function inactivation.

Description

Technical Field

[0001] This invention relates to the field of organic fertilizer technology, specifically to a multifunctional water-soluble fertilizer based on biostimulants and its preparation method. Background Technology

[0002] With the continuous and in-depth promotion of the policy of replacing chemical fertilizers with organic fertilizers in the agricultural field, water-soluble fertilizers containing organic matter combine the advantages of organic fertilizers in improving soil and enhancing the quality of agricultural products, with the characteristics of water-soluble fertilizers such as high solubility, rapid absorption, and convenient precise application of fertigation. They can not only meet the nutrient requirements of crop growth, but also improve soil structure and ecological environment. Among them, biostimulants are a class of active substances derived from organisms that can improve nutrient utilization efficiency, enhance stress resistance, and improve crop quality by regulating plant physiological processes (such as humic acid, small peptides, oligosaccharides, natural growth regulators, etc.). They have become a key component for enhancing the added value of water-soluble fertilizers. Their mechanism of action is not to directly provide nutrients, but to stimulate the plant's own potential through synergistic effects.

[0003] For example, Chinese publication CN 118108552 A discloses a multifunctional water-soluble fertilizer and its preparation method. It discloses that by adding specific amounts of organic matter, bioactive substances and functional additives to the water-soluble fertilizer, a multifunctional water-soluble fertilizer with multiple functions is obtained. In addition to promoting crop growth, the water-soluble fertilizer can also improve soil structure, enhance crop disease resistance, and thus indirectly improve crop yield and quality.

[0004] However, in the process of converting traditional organic fertilizers into high-quality water-soluble fertilizers, existing technologies often employ high-temperature hydrolysis with strong acids or alkalis to enhance the solubility of organic raw materials (such as livestock and poultry manure and oilseed cake). While this method can degrade macromolecules, it leads to the significant inactivation or degradation of heat-sensitive and acid-base-sensitive bioactive substances (such as native enzymes, vitamins, specific oligosaccharides, and natural plant growth regulators). The products are mostly simple amino acids and humic acids, resulting in poor original complex biostimulatory functions of organic fertilizers. Furthermore, in functional water-soluble fertilizers, biostimulants often exist in a free or simple physically adsorbed state. After application to the soil, they are easily leached away by water in sandy soils and easily fixed by soil colloids in clay soils. Their release rate is entirely passive and does not match the nutrient requirements of crops, resulting in low fertilizer utilization. Summary of the Invention

[0005] To address this issue, the present invention provides a multifunctional water-soluble fertilizer based on biostimulants and its preparation method, thereby solving the problem that in the prior art, the conversion of organic fertilizer leads to the inactivation or degradation of a large number of bioactive substances, and at the same time, biostimulants mostly exist in a free state or a simple physical adsorption state, which is not compatible with the fertilizer requirements of crops.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] Firstly, a multifunctional water-soluble fertilizer based on biostimulants, comprising the following components by weight: 30-45 parts organic fertilizer extract, 10-20 parts biostimulant suspension; 6-10 parts calcium nitrate, 4-8 parts potassium nitrate, 3-6 parts potassium dihydrogen phosphate, 0.2-0.5 parts EDTA chelated zinc, 0.1-0.4 parts EDTA chelated magnesium, 25-35 parts deionized water, and 1-3 parts dispersant.

[0008] Furthermore, the biostimulant suspension comprises, by weight, the following components: 0.05-0.4 parts biostimulant, 1.0-2.0 parts sodium alginate, 0.1-0.6 parts emulsifier, 2.0-3.0 parts potassium humate, 1.5-2.5 parts chitosan hydrochloride, 0.5-1.0 parts sodium tripolyphosphate, and 1-20 parts anhydrous ethanol.

[0009] Furthermore, the biostimulant is at least one of brassinolide, gibberellin GA3, or sodium nitrophenolate.

[0010] Furthermore, the organic fertilizer extract is prepared from plant-derived organic fertilizer through a stepwise directional enzymatic hydrolysis using enzyme preparations; the enzyme preparation combination includes at least one of neutral protease, cellulase, and amylase.

[0011] Furthermore, the dispersant is a mixture of lignin sulfonate and sodium hexametaphosphate in a mass ratio of 1-2:1.5-3.

[0012] Secondly, a method for preparing a multifunctional water-soluble fertilizer based on biostimulants includes the following steps:

[0013] S1: Plant-derived organic fertilizer is prepared into organic fertilizer extract by stepwise directional enzymatic hydrolysis and then divided into extract A and extract B by mass ratio;

[0014] S2: Biostimulant is dissolved in anhydrous ethanol as core material, and interfacial ionic gelation is carried out between negatively charged mineral potassium humate and positively charged chitosan hydrochloride under the induction of TPP crosslinking agent to obtain biostimulant suspension.

[0015] S3: A solution was prepared based on calcium nitrate, potassium nitrate, potassium dihydrogen phosphate, zinc chelated by EDTA, and magnesium chelated by EDTA.

[0016] S4: The organic fertilizer extract, biostimulant suspension, and solvent are mixed at low temperature in stages to obtain the finished water-soluble fertilizer.

[0017] Furthermore, the specific steps of S1 are as follows:

[0018] S1.1: Raw material pretreatment: Select plant-derived organic fertilizer with a fermentation maturity of ≥90%, crush it through a 60-mesh sieve, add deionized water at a solid-liquid ratio of 1:5 and mix evenly, then adjust the pH to 6.5-7.0 with sodium hydroxide.

[0019] S1.2: First enzymatic hydrolysis stage: Add 0.5-1 part of neutral protease and 0.2-0.5 part of cellulase to the pretreated solution, and enzymatically hydrolyze for 1.5-2 hours at 45-50℃;

[0020] S1.3: Second enzymatic hydrolysis stage: After the first enzymatic hydrolysis stage is completed, the temperature is raised to 50-55℃, 0.3-0.8 parts of compound peptidase and 0.1-0.3 parts of amylase are added, and enzymatic hydrolysis is continued for 2.5-3 hours;

[0021] S1.4: After enzymatic hydrolysis, the solution is filtered using an ultrafiltration membrane with a molecular weight cutoff of 10000 Da to remove undissolved residues and large-molecule enzyme proteins. The filtrate is collected and pasteurized at 75-80℃ for 10-15 minutes, then rapidly cooled to room temperature to obtain an organic fertilizer extract. The extract is then divided into extract A and extract B at a mass ratio of 4:6.

[0022] Furthermore, the specific steps of S2 are as follows:

[0023] S2.1: Take 0.05-0.4 parts of biostimulant and dissolve it in a mixed solvent of anhydrous ethanol and deionized water to obtain the core material oil phase;

[0024] Take 1.0-2.0 parts of sodium alginate and dissolve it in 95-100 parts of deionized water to prepare a sodium alginate aqueous solution with a mass fraction of 1.0%-2.0%.

[0025] Take 0.01-0.06 parts of emulsifier and add it to sodium alginate aqueous solution, then stir until homogeneous;

[0026] S2.2: Under the action of an emulsifier, the core material oil phase is slowly dripped into an aqueous solution of sodium alginate containing emulsifier, and shearing is continued for 10-15 minutes to form a microemulsion;

[0027] S2.3: Take 2.0-3.0 parts of mineral-derived potassium humate, dissolve it in 95-100 parts of deionized water, adjust the pH to 8.0-9.0 with sodium hydroxide to make it negatively charged, and prepare a mineral-derived potassium humate aqueous solution with a mass fraction of 2.0%-3.0%.

[0028] Take 1.5-2.5 parts of chitosan hydrochloride, dissolve it in 95-100 parts of deionized water, adjust the pH to 4.5-5.0 with hydrochloric acid to make it positively charged, and prepare a chitosan hydrochloride aqueous solution with a mass fraction of 1.5%-2.5%.

[0029] S2.4: The potassium humate solution prepared in S2.3 and the chitosan hydrochloride solution are mixed at a volume ratio of 1:1 under stirring to obtain a prepolymer solution of the polyelectrolyte complex.

[0030] Furthermore, the specific steps of S3 are as follows:

[0031] S3.1: Add 6-10 parts of calcium nitrate to a stirred reactor and add an equal amount of deionized water to prepare a 50% aqueous solution, controlling the water temperature at 25-30℃; according to the mass ratio of calcium ions to extract A of 1:1.5-2.5, add the corresponding amount of extract A to the stirred reactor; turn on the stirrer and stir for 20-40 minutes at a constant temperature of 25-30℃ to obtain a pre-complexed calcium solution;

[0032] S3.2: Add 15-20 parts of deionized water to the stirred reactor, turn on the stirrer, turn the speed to 150-200 r / min, control the water temperature to 25-35℃, and add potassium nitrate, potassium dihydrogen phosphate, pre-complexed calcium solution, EDTA chelated zinc, EDTA chelated magnesium and deionized water in sequence, and stir thoroughly.

[0033] S3.3: After mixing, the liquid is filtered through a 200-mesh stainless steel filter to remove trace amounts of insoluble matter, thus obtaining a solution.

[0034] Furthermore, S4 includes the following steps:

[0035] S4.1: Maintain the reactor temperature at 20-38℃ and the rotation speed at 150-180r / min. Add extract B to the solution using a metering pump at a flow rate of 5-10L / min.

[0036] S4.2: Reduce the stirring speed of the reactor to 150-200 r / min, and slowly add the biostimulant suspension obtained in S2 into the reactor through the bottom valve or side wall inlet at a flow rate of 3-8 L / min; continue stirring at low temperature for 10-15 minutes.

[0037] S4.3: Increase the stirring speed of the reactor to 300-400 r / min, add the dispersant, and stir for 20-30 minutes to obtain the water-soluble fertilizer product.

[0038] The present invention has the following advantages: The present invention replaces the traditional strong acid and strong alkali high-temperature hydrolysis with a step-by-step directional enzymatic hydrolysis process. Under the mild conditions of 45-55℃, a specific enzyme system is used to convert macromolecular organic matter into small molecules, which preserves the original heat-sensitive bioactive substances in organic fertilizers to the greatest extent and solves the problem of biostimulation function inactivation caused by traditional processes.

[0039] Meanwhile, the prepared fulvic acid-chitosan-TPP microcapsules encapsulate biostimulants, keeping them inert in storage and in neutral soil environments. They only disintegrate and release nutrients in the acidic microenvironment of the crop rhizosphere (pH 4.5-5.5), solving the problems of uncontrollable release, easy leaching, or fixation by the soil in existing products. This achieves precise matching between nutrient release and the peak fertilizer demand period of crops.

[0040] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0041] To more intuitively illustrate the prior art and this application, exemplary drawings are provided below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing this application; for example, based on the technical concept disclosed in this application and the exemplary drawings, those skilled in the art are able to easily make conventional adjustments or further optimizations to the addition / reduction / classification, specific shapes, positional relationships, connection methods, size ratios, etc. of certain units (components).

[0042] Figure 1 This is a flowchart illustrating the preparation method of a multifunctional water-soluble fertilizer based on biostimulants according to the present invention. Detailed Implementation

[0043] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these embodiments are merely for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Technical engineers in the field can make some non-essential improvements and adjustments to the present invention based on the above-described content. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] A multifunctional water-soluble fertilizer based on biostimulants, comprising the following components by weight: 30-45 parts organic fertilizer extract, 10-20 parts biostimulant suspension; 6-10 parts calcium nitrate, 4-8 parts potassium nitrate, 3-6 parts potassium dihydrogen phosphate, 0.2-0.5 parts EDTA chelated zinc, 0.1-0.4 parts EDTA chelated magnesium, 25-35 parts deionized water, and 1-3 parts dispersant.

[0045] The organic fertilizer extract is prepared by stepwise enzymatic hydrolysis of plant-derived organic fertilizers using enzyme preparations. The extract contains small peptides (molecular weight <1000 Da), oligosaccharides, free amino acids, nucleotides, and natural auxins, with a viscosity of 20-40 mPa·s. The plant-derived organic fertilizer is selected from at least one of soybean meal, rapeseed cake, or sesame cake with a fermentation maturity ≥90%. The enzyme preparation combination includes at least one of neutral protease, cellulase, and amylase. It is used to efficiently degrade the large molecular proteins and cellulose in plant-derived organic fertilizers into bioactive substances rich in small peptides, oligosaccharides, and free amino acids.

[0046] Calcium nitrate is a water-soluble source of calcium and nitrogen, providing crops with readily available calcium nutrients to prevent calcium deficiency physiological diseases, while also providing nitrate nitrogen to promote rapid absorption by crops; potassium nitrate provides water-soluble sources of potassium and nitrogen to meet the large demand for potassium during the reproductive growth stage of crops, promoting the transport of photosynthetic products and fruit enlargement; potassium dihydrogen phosphate provides sources of phosphorus and potassium, with phosphorus promoting root development and flower bud differentiation, and potassium enhancing stress resistance and fruit quality; EDTA chelated zinc provides stable and effective zinc in chelated form to prevent physiological diseases such as small leaves and bushy growth caused by zinc deficiency in crops; EDTA chelated magnesium provides stable and effective magnesium in chelated form to prevent magnesium deficiency-induced yellowing leaves; deionized water is used as the solvent medium.

[0047] The biostimulant suspension comprises, by weight, the following components: 0.05-0.4 parts biostimulant, 1.0-2.0 parts sodium alginate, 0.1-0.6 parts emulsifier, 2.0-3.0 parts potassium humate, 1.5-2.5 parts chitosan hydrochloride, 0.5-1.0 parts sodium tripolyphosphate, and 1-20 parts anhydrous ethanol.

[0048] Among them, the biostimulant is at least one of brassinolide, gibberellin GA3, or sodium nitrophenolate; the emulsifier is used to disperse and encapsulate the biostimulant dissolved in anhydrous ethanol to form a stable oil-in-water microemulsion; sodium alginate is used as the microcapsule wall material and cross-links with calcium ions to solidify; potassium humate solution and chitosan hydrochloride solution are used to form a polyelectrolyte complex through electrostatic self-assembly and ionic gelation; sodium tripolyphosphate is used as a cross-linking agent to induce ionic gelation of chitosan.

[0049] The dispersant is a mixture of lignin sulfonate and sodium hexametaphosphate in a mass ratio of 1-2:1.5-3. The lignin sulfonate is used to provide steric hindrance to prevent microcapsule aggregation, and the sodium hexametaphosphate is used to complex free calcium and magnesium ions.

[0050] The small peptides, oligosaccharides, and free amino acids in the deep enzymatic hydrolysate of the above-mentioned multifunctional water-soluble fertilizer provide fast-acting nutrients that can be directly absorbed by crop roots; the microcapsule structure enables a slow-release function, allowing it to disintegrate only in the microenvironment of acidic substances secreted by the roots to release biostimulants; and the mineral-derived potassium humate and chitosan degradation products improve soil aggregate structure to achieve soil improvement function.

[0051] Please see Figure 1 A method for preparing a multifunctional water-soluble fertilizer based on biostimulants includes the following steps:

[0052] S1: Plant-derived organic fertilizers are prepared into organic fertilizer extracts through stepwise directional enzymatic hydrolysis; this facilitates the preparation of highly active, low-molecular-weight biostimulant mother liquor, providing key functional components that can form stable complexes with calcium ions and induce rhizosphere responses in microcapsules for subsequent steps.

[0053] The specific steps of S1 are as follows:

[0054] S1.1: Raw material pretreatment: Select plant-derived organic fertilizer with a fermentation maturity of ≥90%, crush it through a 60-mesh sieve, add deionized water at a solid-liquid ratio of 1:5 (w / v) and mix evenly, then adjust the pH to 6.5-7.0 with sodium hydroxide.

[0055] S1.2: First enzymatic hydrolysis stage: Add 0.5-1 part of neutral protease (activity ≥50000U / g) and 0.2-0.5 part of cellulase (activity ≥10000U / g) to the pretreated solution, and enzymatically hydrolyze for 1.5-2 hours at 45-50℃ to break down plant cell walls and release intracellular nutrients.

[0056] S1.3: Second enzymatic hydrolysis stage: After the first enzymatic hydrolysis stage is completed, the temperature is raised to 50-55℃, and 0.3-0.8 parts of compound peptidase (a combination of endopeptidase and exopeptidase, with an activity ≥80000U / g) and 0.1-0.3 parts of amylase (with an activity ≥20000U / g) are added. Enzymatic hydrolysis is continued for 2.5-3 hours to directionally convert large molecular proteins and polysaccharides into products mainly composed of small peptides and oligosaccharides, controlling the molecular weight of the product to <1000Da;

[0057] S1.4: After enzymatic hydrolysis, the solution is filtered using an ultrafiltration membrane with a molecular weight cutoff of 10000 Da to remove undissolved residues and large-molecule enzyme proteins. The filtrate is collected and pasteurized at 75-80℃ for 10-15 minutes, then rapidly cooled to room temperature to obtain an organic fertilizer extract. This extract is then divided into extract A and extract B at a mass ratio of 4:6. This extract is rich in small peptides, free amino acids, nucleotides, and natural growth hormones.

[0058] S2: Preparation of Biostimulant Suspension: Biostimulants are dissolved in anhydrous ethanol as the core material. Interfacial ionic gelation occurs between negatively charged mineral-derived potassium humate and positively charged chitosan hydrochloride under the induction of a TPP crosslinking agent. This self-assembly forms a dense three-dimensional network wall material that encapsulates the core material, ultimately yielding a biostimulant suspension with a particle size of 5-15 μm. This ensures the biostimulant remains stable during storage and in neutral soil environments, rapidly disintegrating and releasing only in the acidic microenvironment of the crop rhizosphere. This achieves matching between the biostimulant and the peak nutrient demand period of crops, solving the problems of uncontrollable release and low utilization rates of existing products.

[0059] The specific steps of S2 are as follows:

[0060] S2.1: Take 0.05-0.4 parts of biostimulant and dissolve it in a mixed solvent of anhydrous ethanol and deionized water (where the volume percentage of anhydrous ethanol is 60%-90%) to obtain the core material oil phase; take 1.0-2.0 parts of sodium alginate and dissolve it in 95-100 parts of deionized water to prepare a sodium alginate aqueous solution with a mass fraction of 1.0%-2.0%;

[0061] Take 0.01-0.06 parts of emulsifier and add it to sodium alginate aqueous solution, then stir until homogeneous;

[0062] S2.2: Under the action of an emulsifier (speed 6000-8000r / min), the core material oil phase is slowly dripped into an aqueous solution of sodium alginate containing emulsifier, and shearing is continued for 10-15 minutes to form a stable oil-in-water (O / W) microemulsion as the core material dispersion phase;

[0063] S2.3: Take 2.0-3.0 parts of mineral-derived potassium humate, dissolve it in 95-100 parts of deionized water, adjust the pH to 8.0-9.0 with sodium hydroxide to make it negatively charged, and prepare a mineral-derived potassium humate aqueous solution with a mass fraction of 2.0%-3.0%.

[0064] Take 1.5-2.5 parts of chitosan hydrochloride, dissolve it in 95-100 parts of deionized water, adjust the pH to 4.5-5.0 with hydrochloric acid to make it positively charged, and prepare a chitosan hydrochloride aqueous solution with a mass fraction of 1.5%-2.5%.

[0065] S2.4: Interfacial ionic gelation coating: The mineral-derived potassium humate solution prepared in S2.3 and the chitosan hydrochloride solution were mixed at a volume ratio of 1:1 under stirring to obtain a prepolymer solution of the polyelectrolyte complex.

[0066] The microemulsion prepared in S2.2 is then slowly added dropwise to the prepolymer solution, while simultaneously adding 0.5-1.0 parts of a 0.5%-1.0% sodium tripolyphosphate (TPP) aqueous solution as a crosslinking agent. The addition time is controlled at 30-45 minutes. TPP induces chitosan to undergo ionic gelation and self-assembles with fulvic acid on the surface of the core material droplets through hydrogen bonding and electrostatic interactions, forming a fulvic acid-chitosan-TPP three-dimensional network wall material.

[0067] S2.5: Adjust the shear speed of the emulsifier to 2000-3500 rpm to provide turbulent shear force, and control the concentration of chitosan and TPP within the range of 0.8%-1.5% (w / v) to maintain the solution viscosity and film-forming properties. Simultaneously adjust the TPP drop rate to 0.5-1.5 mL / min to ensure uniform ionic cross-linking reaction, thereby generating microcapsules with a particle size of 5-15 μm and obtaining a biostimulant suspension.

[0068] S3: Based on calcium nitrate, potassium nitrate, potassium dihydrogen phosphate, EDTA chelated zinc, and EDTA chelated magnesium, a solution is prepared to facilitate the protection of calcium ions through small peptide pre-complexation and combined with a specific sequential feeding process, effectively avoiding precipitation reactions between high concentrations of calcium ions and organic components such as phosphate and humic acid.

[0069] The specific steps for S3 are as follows:

[0070] S3.1: In a stirred reactor, add 6-10 parts of calcium nitrate and an equal amount of deionized water to prepare a 50% aqueous solution, and control the water temperature at 25-30℃.

[0071] Add the corresponding amount of extract A to the stirred reactor at a mass ratio of calcium ions to extract A of 1:1.5-2.5; turn on the stirrer and control the speed at 120-180 r / min, and stir for 20-40 minutes under constant temperature of 25-30℃ to obtain pre-complexed calcium solution for later use.

[0072] During the reaction, calcium ions undergo a complexation reaction with the carboxyl and amino groups on the small peptide molecular chains in the organic fertilizer extract to form a stable small peptide-calcium complex-2.

[0073] S3.2: Add 15-20 parts of deionized water to the stirred reactor, turn on the stirrer, and set the speed to 150-200 r / min, while controlling the water temperature to 25-35℃;

[0074] Add the following ingredients in order, dissolving each one completely before adding the next:

[0075] First, add potassium nitrate and stir to dissolve for 5-10 minutes; then add potassium dihydrogen phosphate and stir to dissolve for 8-12 minutes; next, add the pre-complexed calcium solution and stir for 10-15 minutes; then add EDTA-chelated zinc and stir for 5-8 minutes; finally, add EDTA-chelated magnesium and stir for 5-8 minutes. After all the raw materials are dissolved, add 10-15 parts of deionized water and continue stirring for 15-20 minutes to ensure that all components are thoroughly mixed. Adding potassium nitrate and potassium dihydrogen phosphate, which have lower solubility, first, followed by the pre-complexed calcium solution, and finally the trace elements, can effectively avoid ion competition and precipitation reactions.

[0076] S3.3: After mixing, the liquid is filtered through a 200-mesh stainless steel filter to remove trace amounts of insoluble matter, thus obtaining a solution;

[0077] S4: The organic fertilizer extract, biostimulant suspension, and dissolving solution are mixed at low temperatures in stages to obtain the finished water-soluble fertilizer. This process ensures sufficient complexation between calcium ions and small peptides while avoiding high shear forces that could damage the microcapsule structure, thus achieving stable integration and uniform suspension of the bioactive components.

[0078] S4 includes the following steps:

[0079] S4.1: Maintain the reactor temperature at 20-38℃ and the rotation speed at 150-180r / min. Add extract B to the solution using a metering pump at a flow rate of 5-10L / min to avoid generating a large amount of foam.

[0080] During the feeding process, stirring is maintained to utilize the small peptides in the organic fertilizer extract to perform secondary deep complexation on the free calcium ions in the solution; this stage involves continuous stirring for 15-20 minutes to ensure that the small peptides and calcium ions are fully combined to form a stable organic-inorganic complex system.

[0081] S4.2: Reduce the stirring speed of the reactor to 150-200 r / min, and slowly add the biostimulant suspension prepared in S2 into the reactor through the bottom valve or side wall inlet at a flow rate of 3-8 L / min; continue stirring at low temperature for 10-15 minutes to ensure that the microcapsules are uniformly suspended in the liquid.

[0082] S4.3: Increase the stirring speed of the reactor to 300-400 r / min (still controlled at low temperature), add the dispersant, stir for 20-30 minutes, and obtain the water-soluble fertilizer product.

[0083] After obtaining the finished water-soluble fertilizer, an online pH meter is needed to monitor the system's pH. The target pH range for the finished product is 6.0-6.5. This pH range ensures the chemical stability of the microcapsule wall material during storage (preventing acidic hydrolysis or alkaline swelling) and also ensures that after the product is applied to the soil, the rhizosphere secretes acidic substances (pH drops to 4.5-5.5), triggering the responsive disintegration of the microcapsules and achieving targeted release.

[0084] If pH < 6.0, add dilute potassium hydroxide solution; if pH > 6.5, add dilute nitric acid solution.

[0085] This invention replaces the traditional high-temperature hydrolysis with strong acid and strong alkali by using a stepwise directional enzymatic hydrolysis process. Under mild conditions of 45-55℃, it uses a specific enzyme system to convert macromolecular organic matter into small molecules, thus preserving the original heat-sensitive bioactive substances in organic fertilizers to the greatest extent and solving the problem of biostimulation function inactivation caused by traditional processes.

[0086] Meanwhile, the prepared fulvic acid-chitosan-TPP microcapsules encapsulate biostimulants, keeping them inert in storage and in neutral soil environments. They only disintegrate and release nutrients in the acidic microenvironment of the crop rhizosphere (pH 4.5-5.5), solving the problems of uncontrollable release, easy leaching, or fixation by the soil in existing products. This achieves precise matching between nutrient release and the peak fertilizer demand period of crops.

[0087] An example is given below:

[0088] Preparation of a multifunctional water-soluble fertilizer based on biostimulants:

[0089] S1: Preparation of Organic Fertilizer Extract: Soybean cake fertilizer with a composting degree of 92% was selected, pulverized, and passed through a 60-mesh sieve. Water was added at a ratio of 1:5 to form a slurry, and the pH was adjusted to 6.8 with NaOH. 0.8 parts of neutral protease and 0.3 parts of cellulase were added, and enzymatic hydrolysis was carried out at 50℃ for 1.5 hours. The temperature was then raised to 53℃, and 0.5 parts of compound peptidase and 0.2 parts of amylase were added, with enzymatic hydrolysis continuing for 2.8 hours. The solution was filtered through a 10000 Da ultrafiltration membrane, and the filtrate was pasteurized at 80℃ for 12 minutes. After cooling, it was divided into extract A and extract B at a ratio of 4:6.

[0090] S2: Preparation of Biostimulant Microcapsules: 0.2 parts of brassinolide were dissolved in an 80% ethanol aqueous solution to obtain the core material; 1.5 parts of sodium alginate were prepared into a 1.5% solution, and 0.03 parts of emulsifier were added. The core material was dropped into the sodium alginate solution at a shear rate of 6000 r / min to form an O / W emulsion. Separately, equal volumes of 2.5% potassium humate solution (pH 8.5) and 2.0% chitosan hydrochloride solution (pH 4.8) were mixed to obtain a prepolymer solution. The emulsion was dropped into the prepolymer solution, and 0.8% TPP solution was added simultaneously (at a rate of 1.0 mL / min). The reaction was allowed to proceed for 40 minutes to form microcapsules. The shear rate was adjusted to 3000 r / min to obtain a biostimulant suspension with a particle size of approximately 10 μm.

[0091] S3: Preparation of macro-element solution: Take 8 parts of calcium nitrate to prepare a 50% solution (30℃), add extract A at a ratio of calcium:extract A = 1:2, and stir at 150 r / min for 30 minutes to complete the pre-complexation. In another reaction vessel, add 18 parts of water, dissolve potassium nitrate and potassium dihydrogen phosphate in sequence, then add the above pre-complexed calcium solution, and finally add EDTA-Zn and EDTA-Mg, add water to the total volume, and filter through a 200 mesh to obtain the solution.

[0092] S4: Staged low-temperature mixing: Maintain the solution temperature at 25℃, add extract B while stirring at 160 rpm, and react for 20 minutes for secondary complexation. Reduce the stirring speed to 170 rpm, slowly add the microcapsule suspension prepared in S2, and stir for 12 minutes. Increase the stirring speed to 350 rpm, add 0.3% sodium lignosulfonate as a dispersant, and stir for 25 minutes. Adjust the pH to 6.2, and fill to obtain the finished product.

[0093] Test case

[0094] One experimental group and two control groups were set up, wherein the experimental group was the water-soluble fertilizer prepared in the example.

[0095] Control group 1 (traditional high-temperature acid-base hydrolysis + free addition):

[0096] Using the same raw materials, but replacing the S1 enzymatic hydrolysis process with 1 mol / L NaOH hydrolysis at 95℃ for 3 hours, ultrafiltration and stepwise complexation were omitted. The hydrolysate was directly acidified and neutralized before being mixed with calcium nitrate, potassium dihydrogen phosphate, and other raw materials in a single step (without a pre-complexation step). The biostimulant (brassinolide) was not prepared into microcapsules but added directly to the final mixture in its free state. The stirring process was not strictly temperature-controlled (naturally heated to 45℃), and the stirring speed was kept constant at 500 r / min.

[0097] Control group 2 (no small peptide pre-complexation + ordinary microcapsules):

[0098] S1 uses an enzymatic hydrolysis process but does not separate A / B solutions. In S3, calcium nitrate is not pre-complexed with the extract and is directly mixed with phosphate (forced filtration is performed after a small amount of turbidity appears). In S2, the microcapsule wall material uses only sodium alginate as a single material, without a fulvic acid-chitosan-TPP cross-linked structure, and does not have pH-responsive characteristics. The mixing process in S4 is the same as in Example 1.

[0099] The experimental data results are shown in the table below:

[0100]

[0101] Comprehensive experimental data show that Example 1 is significantly better than the comparative example in terms of suspension rate (98.5%), calcium ion availability (99.2%), and rhizosphere response release rate (85.3%). This water-soluble fertilizer not only solves the problem of high-concentration calcium and phosphorus precipitation through a mild enzymatic hydrolysis and pre-complexation mechanism, but also realizes the release of nutrients in the acidic environment of the rhizosphere by using microcapsules.

[0102] This approach, encompassing chemical stabilization at the molecular level, physical protection of the microstructure, and low-temperature integration at the process level, resulted in a 134.5% increase in wheat pot yield, far exceeding the traditional process (108.2%). This demonstrates that the solution effectively overcomes the shortcomings of existing fertilizers, such as low utilization rate, uncontrollable release, and easy loss of activity, truly realizing a technological leap from passive application of fertilizers to actively adapting to the fertilizer requirements of crops.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multifunctional water-soluble fertilizer based on biostimulants, characterized in that, By weight, it includes the following components: 30-45 parts organic fertilizer extract and 10-20 parts biostimulant suspension; Calcium nitrate 6-10 parts, potassium nitrate 4-8 parts, potassium dihydrogen phosphate 3-6 parts, EDTA chelated zinc 0.2-0.5 parts, EDTA chelated magnesium 0.1-0.4 parts, deionized water 25-35 parts, dispersant 1-3 parts.

2. The multifunctional water-soluble fertilizer based on biostimulants according to claim 1, characterized in that, The biostimulant suspension comprises, by weight, the following components: 0.05-0.4 parts biostimulant, 1.0-2.0 parts sodium alginate, 0.1-0.6 parts emulsifier, 2.0-3.0 parts potassium humate, 1.5-2.5 parts chitosan hydrochloride, 0.5-1.0 parts sodium tripolyphosphate, and 1-20 parts anhydrous ethanol.

3. The multifunctional water-soluble fertilizer based on biostimulants according to claim 2, characterized in that, The biostimulant is at least one of brassinolide, gibberellin GA3, or sodium nitrophenolate.

4. The multifunctional water-soluble fertilizer based on biostimulants according to claim 1, characterized in that, The organic fertilizer extract is prepared by stepwise directional enzymatic hydrolysis of plant-derived organic fertilizer using enzyme preparations; the enzyme preparation combination includes at least one of neutral protease, cellulase and amylase.

5. A multifunctional water-soluble fertilizer based on biostimulants according to claim 1, characterized in that, The dispersant is a mixture of lignin sulfonate and sodium hexametaphosphate in a mass ratio of 1-2:1.5-3.

6. A method for preparing a multifunctional water-soluble fertilizer based on biostimulants, characterized in that, Includes the following steps: S1: Plant-derived organic fertilizer is prepared into organic fertilizer extract by stepwise directional enzymatic hydrolysis, and then divided into extract A and extract B by mass ratio; S2: Biostimulant is dissolved in anhydrous ethanol as core material, and interfacial ionic gelation is carried out between negatively charged mineral potassium humate and positively charged chitosan hydrochloride under the induction of TPP crosslinking agent to obtain biostimulant suspension. S3: A solution was prepared based on calcium nitrate, potassium nitrate, potassium dihydrogen phosphate, zinc chelated by EDTA, and magnesium chelated by EDTA. S4: The organic fertilizer extract, biostimulant suspension, and solvent are mixed at low temperature in stages to obtain the finished water-soluble fertilizer.

7. The method for preparing a multifunctional water-soluble fertilizer based on biostimulants according to claim 6, characterized in that, The specific steps of S1 are as follows: S1.1: Raw material pretreatment: Select plant-derived organic fertilizer with a fermentation maturity of ≥90%, crush it through a 60-mesh sieve, add deionized water at a solid-liquid ratio of 1:5 and mix evenly, then adjust the pH to 6.5-7.0 with sodium hydroxide. S1.2: First enzymatic hydrolysis stage: Add 0.5-1 part of neutral protease and 0.2-0.5 part of cellulase to the pretreated solution, and enzymatically hydrolyze for 1.5-2 hours at 45-50℃; S1.3: Second enzymatic hydrolysis stage: After the first enzymatic hydrolysis stage is completed, the temperature is raised to 50-55℃, 0.3-0.8 parts of compound peptidase and 0.1-0.3 parts of amylase are added, and enzymatic hydrolysis is continued for 2.5-3 hours; S1.4: After enzymatic hydrolysis, the solution is filtered using an ultrafiltration membrane with a molecular weight cutoff of 10000 Da to remove undissolved residues and large-molecule enzyme proteins. The filtrate is collected and pasteurized at 75-80℃ for 10-15 minutes, then rapidly cooled to room temperature to obtain an organic fertilizer extract. The extract is then divided into extract A and extract B at a mass ratio of 4:

6.

8. The method for preparing a multifunctional water-soluble fertilizer based on biostimulants according to claim 6, characterized in that, The specific steps of S2 are as follows: S2.1: Take 0.05-0.4 parts of biostimulant and dissolve it in a mixed solvent of anhydrous ethanol and deionized water to obtain the core material oil phase; Take 1.0-2.0 parts of sodium alginate and dissolve it in 95-100 parts of deionized water to prepare a sodium alginate aqueous solution with a mass fraction of 1.0%-2.0%. Take 0.01-0.06 parts of emulsifier and add it to sodium alginate aqueous solution, then stir until homogeneous; S2.2: Under the action of an emulsifier, the core material oil phase is slowly dripped into an aqueous solution of sodium alginate containing emulsifier, and shearing is continued for 10-15 minutes to form a microemulsion; S2.3: Take 2.0-3.0 parts of mineral-derived potassium humate, dissolve it in 95-100 parts of deionized water, adjust the pH to 8.0-9.0 with sodium hydroxide to make it negatively charged, and prepare a mineral-derived potassium humate aqueous solution with a mass fraction of 2.0%-3.0%. Take 1.5-2.5 parts of chitosan hydrochloride, dissolve it in 95-100 parts of deionized water, adjust the pH to 4.5-5.0 with hydrochloric acid to make it positively charged, and prepare a chitosan hydrochloride aqueous solution with a mass fraction of 1.5%-2.5%. S2.4: The potassium humate solution prepared in S2.3 and the chitosan hydrochloride solution are mixed at a volume ratio of 1:1 under stirring to obtain a prepolymer solution of the polyelectrolyte complex.

9. The method for preparing a multifunctional water-soluble fertilizer based on biostimulants according to claim 6, characterized in that, The specific steps of S3 are as follows: S3.1: Add 6-10 parts of calcium nitrate to a stirred reactor and add an equal amount of deionized water to prepare a 50% aqueous solution, controlling the water temperature at 25-30℃; according to the mass ratio of calcium ions to extract A of 1:1.5-2.5, add the corresponding amount of extract A to the stirred reactor; turn on the stirrer and stir for 20-40 minutes at a constant temperature of 25-30℃ to obtain a pre-complexed calcium solution; S3.2: Add 15-20 parts of deionized water to the stirred reactor, turn on the stirrer, turn the speed to 150-200 r / min, control the water temperature to 25-35℃, and add potassium nitrate, potassium dihydrogen phosphate, pre-complexed calcium solution, EDTA chelated zinc, EDTA chelated magnesium and deionized water in sequence, and stir thoroughly. S3.3: After mixing, the liquid is filtered through a 200-mesh stainless steel filter to remove trace amounts of insoluble matter, thus obtaining a solution.

10. The method for preparing a multifunctional water-soluble fertilizer based on biostimulants according to claim 6, characterized in that, S4 includes the following steps: S4.1: Maintain the reactor temperature at 20-38℃ and the rotation speed at 150-180r / min. Add extract B to the solution using a metering pump at a flow rate of 5-10L / min. S4.2: Reduce the stirring speed of the reactor to 150-200 r / min, and slowly add the biostimulant suspension obtained in S2 into the reactor through the bottom valve or side wall inlet at a flow rate of 3-8 L / min. Continue to stir at low temperature for 10-15 minutes. S4.3: Increase the stirring speed of the reactor to 300-400 r / min, add the dispersant, and stir for 20-30 minutes to obtain the water-soluble fertilizer product.

Images