Quaternary synergistic water-soluble fertilizer synergist as well as preparation method and application thereof

Abstract

The invention discloses a quaternary synergistic water-soluble fertilizer synergist as well as a preparation method and application thereof, and realizes deep coupling of chemical growth promotion, biological activation and physical slow release, multi-component synergistic interaction and efficient nutrient utilization based on a four-dimensional synergistic mechanism of chitosan oligosaccharide-oligopeptide-bioactive alkali-functional microbial agent. Wherein the modified chitosan oligosaccharide enhances the chelating ability through molecular structure optimization, and forms a nano-scale composite system with the oligopeptide, so that the absorption and transfer efficiency of nutrients on leaf surfaces and root systems is remarkably improved. The functional microbial agent and chitosan oligosaccharide cooperate to activate soil enzyme activity and promote release of insoluble phosphorus and potassium, so that the utilization rate of nitrogen, phosphorus and potassium is remarkably increased compared with that of a traditional fertilizer, and nutrient loss is effectively reduced. The quaternary synergistic water-soluble fertilizer synergist provided by the invention is high in compatibility, can be directly compounded with a commercially available water-soluble fertilizer for use, is suitable for diversified planting scenes of facility agriculture, field crops and commercial crops, and has large-scale popularization potential.

Description

Technical Field

[0001] This invention relates to the field of agricultural fertilizer technology, specifically to a quaternary synergistic water-soluble fertilizer enhancer, its preparation method, and its application. Background Technology

[0002] In agricultural production, water-soluble fertilizers are widely used in precision agriculture due to their rapid nutrient delivery and convenient application. However, current water-soluble fertilizer synergists generally suffer from limitations such as single function and insufficient synergy. Traditional nitrogen, phosphorus, and potassium fertilizers, after being applied to the soil, are easily subject to volatilization, fixation, or leaching, resulting in insufficient fertilizer utilization and failing to meet the crop's demand for efficient nutrient absorption.

[0003] Commercially available water-soluble fertilizer synergists, such as nitrification inhibitors or humic acid, can only target a single nutrient loss pathway and lack the ability to regulate the overall soil-crop system. For example, while common chitosan oligosaccharides can promote crop growth, their molecular structure makes them easily degraded by soil microorganisms, resulting in a half-life of less than a week. Furthermore, their chelation stability with micronutrients is poor, making it difficult to sustain their synergistic effect. In high-salt liquid fertilizer environments, microbial inoculants suffer from osmotic pressure imbalances, leading to a significant decrease in survival rate and an inability to coexist stably with chemical components, thus limiting their application scope.

[0004] Furthermore, long-term application of water-soluble fertilizers can lead to soil acidification and secondary salinization. Current technologies largely rely on chemical conditioners such as polyacrylamide to improve soil structure in the short term, but this method carries the risk of microplastic residues and cannot simultaneously achieve slow nutrient release and microbial colonization, failing to fundamentally address the synergistic issue of soil health and efficient fertilizer utilization. Therefore, there is an urgent need to develop a novel synergist that can overcome these shortcomings, effectively improve the nutrient utilization efficiency of water-soluble fertilizers, and simultaneously enhance crop stress resistance and regulate soil health. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a quaternary synergistic water-soluble fertilizer enhancer, its preparation method, and its application. This water-soluble fertilizer enhancer significantly improves the nutrient utilization efficiency of water-soluble fertilizers through the stabilization and chelation of modified chitosan oligosaccharides, the slow-release loading of functional microorganisms, and the multi-component synergistic enhancement mechanism. Simultaneously, it can also enhance crop stress resistance and regulate soil health. It is widely applicable to various precision agriculture application scenarios such as drip irrigation, fertigation, and foliar spraying.

[0006] The above-mentioned objective of this invention is achieved through the following technical solutions:

[0007] The first aspect of this invention provides a quaternary synergistic water-soluble fertilizer synergist, which is composed of the following components in the following mass percentages: 0.5%-3% modified chitosan oligosaccharide, 1.5%-6% plant-derived oligopeptide, 0.5%-2% animal-derived oligopeptide, 0.1%-1.8% bioactive alkali, 0.8%-2% functional microbial agent, 5%-12% auxiliary synergistic component, 0.1%-0.5% pH adjuster, 0.01%-0.1% stabilizer, and the balance being water; wherein the modified chitosan oligosaccharide is phenolic acid-grafted chitosan oligosaccharide; and the auxiliary synergistic component includes amino acid-chelated trace elements, alkali-modified humic acid, and a slow-release carrier.

[0008] To address the problems of traditional fertilizer synergists, such as limited functionality, poor microbial activity, and soil degradation, this invention constructs a quaternary synergistic system of "chitosan oligosaccharide-oligopeptide-bioactive alkali-functional microbial agent," combining a physical slow-release carrier with targeted chelation technology to achieve comprehensive performance enhancement of water-soluble fertilizers. Specifically, modified chitosan oligosaccharide and oligopeptide form nanoscale micelles, significantly enhancing nutrient absorption efficiency; the functional microbial agent synergistically works with the slow-release carrier to ensure agent activity and long-term colonization; and the bioactive alkali activates crop stress-resistance genes, working synergistically with the slow-release carrier to achieve soil pH balance and salinization remediation. The synergist of this invention can be directly compounded with commercially available water-soluble fertilizers, suitable for drip irrigation, fertigation, and foliar spraying. It is environmentally friendly, highly adaptable, and can effectively reduce fertilizer usage, improve crop quality and soil health, making it suitable for various planting scenarios such as facility agriculture and saline-alkali land improvement.

[0009] Furthermore, the quaternary synergistic water-soluble fertilizer enhancer is composed of the following components in the following mass percentages: modified chitosan oligosaccharide 0.5%-3%, plant-derived oligopeptides 1.5%-6%, animal-derived oligopeptides 0.5%-2%, bioactive alkali 0.1%-1.8%, functional microbial agent 0.8%-2%, amino acid chelated trace elements 0.5%-2%, alkali-modified humic acid 3%-5%, slow-release carrier 1.5%-5%, pH adjuster 0.1%-0.5%, stabilizer 0.01%-0.1%, and the balance being water.

[0010] Furthermore, the amino acid chelated trace elements include glycine chelated iron, proline chelated zinc, and glutamic acid chelated boron, and the chelation degree of the amino acid chelated trace elements is ≥90%.

[0011] Furthermore, the alkali-modified humic acid is prepared by alkali modification of lignite as raw material, the carboxyl content in the alkali-modified humic acid is ≥4.2mmol / g, and the water solubility of the alkali-modified humic acid is ≥95%.

[0012] Furthermore, the alkali can be KOH, and the conditions for the alkali modification treatment are: system pH = 7-9.

[0013] Furthermore, the sustained-release carrier comprises amidated pectin and corn cob particles.

[0014] Furthermore, the mass ratio of the amidated pectin to corn cob particles is (0.8-1.2):1, preferably 1:1.

[0015] Furthermore, the degree of esterification of the amidated pectin is ≥70%, the porosity of the amidated pectin is 60-70%, and the particle size of the corn cob particles is 0.3-0.8 mm.

[0016] Furthermore, the modified chitosan oligosaccharide is prepared by the following method:

[0017] a) Chitosan was prepared by using the shells of crustaceans as raw materials, after decalcification by acid treatment, and then by enzymatic hydrolysis.

[0018] b) Dissolve phenolic acid in a polar solvent, add an activator to obtain an activated phenolic acid solution; the phenolic acid is selected from at least one of gallic acid, p-coumaric acid and protocatechuic acid, and the molar ratio of phenolic acid to activator is 1:(1-3);

[0019] c) Add the chitosan oligosaccharide obtained in step a) to the activated phenolic acid solution, wherein the molar ratio of chitosan oligosaccharide to phenolic acid is 1:(0.5-2), and the reaction yields the grafted product;

[0020] d) The grafted product was precipitated with an organic solvent, and unreacted monomers were removed by filtration. The product was then spray-dried to obtain phenolic acid-grafted chitosan oligosaccharide, which is the modified chitosan oligosaccharide.

[0021] Further, in step a), the acid treatment conditions are: HCl concentration of 2-4 mol / L and temperature of 80-90℃.

[0022] Furthermore, in step a), the degree of deacetylation of the chitosan prepared by the enzymatic hydrolysis method is ≥90%.

[0023] Furthermore, step a) also includes a step of degrading chitosan using a hydrogen peroxide-ascorbic acid composite degradation system.

[0024] Furthermore, the degradation treatment conditions are as follows: H2O2 concentration of 5%-8%, ascorbic acid addition of 0.1%-0.3%, and temperature of 50-60℃.

[0025] Further, in step a), chitosan with a molecular weight of 1000-5000 Da is prepared by enzymatic hydrolysis.

[0026] Further, in step b), the polar solvent is dimethyl sulfoxide buffer.

[0027] Further, in step b), the activator is 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS), and the molar ratio of EDC to NHS is 1:1.

[0028] Further, in step b), the molar ratio of the phenolic acid to the activator is 1:(1-1.2).

[0029] Further, in step c), the reaction conditions are: reacting at 40-60℃ for 6-12 hours, and during the reaction, ultrasonic assistance is used to promote the directional grafting of amino / hydroxyl groups.

[0030] Furthermore, the conditions for ultrasound assistance are a frequency of 20-40kHz and a power density of 50-100W / L.

[0031] Further, in step d), the organic solvent is anhydrous ethanol.

[0032] In a specific embodiment, the preparation method of the modified chitosan oligosaccharide includes the following steps:

[0033] a) Preparation of chitosan oligosaccharides: Using crustacean shells as raw materials, after decalcification by acid treatment (HCl concentration of 2-4 mol / L, temperature of 80-90℃), chitosan (degree of deacetylation ≥90%) is prepared by enzymatic hydrolysis. The chitosan is then subjected to controlled degradation in a hydrogen peroxide-ascorbic acid composite degradation system (H2O2 concentration of 5%-8%, ascorbic acid addition of 0.1%-0.3%, temperature of 50-60℃) for 2-4 hours to obtain chitosan oligosaccharides with a molecular weight of 1000-5000 Da.

[0034] b) Phenolic acid activation: Dissolve phenolic acid in a polar solvent (dimethyl sulfoxide buffer), add activator (EDC / NHS composite system (molar ratio of 1:1)) and activate at 30-35℃ for 2-4 hours to obtain an activated phenolic acid solution; the phenolic acid is selected from at least one of gallic acid, p-coumaric acid and protocatechuic acid, and the molar ratio of phenolic acid to activator is 1:(1-3).

[0035] c) Grafting reaction: The chitosan oligosaccharide obtained in step a) is added to the activated phenolic acid solution, and the molar ratio of chitosan oligosaccharide to phenolic acid is controlled at 1:(0.5-2). The reaction is carried out at 40-60℃ for 6-12 hours. During the reaction, the directional grafting of amino / hydroxyl groups is promoted by ultrasonic assistance (frequency 20-40kHz, power density 50-100W / L) to obtain the grafted product.

[0036] d) Purification: After the reaction, the grafted product was precipitated with anhydrous ethanol, and unreacted monomers were removed by filtration through a 0.45 μm membrane. Then, the modified chitosan oligosaccharide (phenolic acid grafted chitosan oligosaccharide) was obtained by spray drying.

[0037] Furthermore, the plant-derived oligopeptide is a soybean oligopeptide.

[0038] Furthermore, the soybean oligopeptides are prepared by the following method: soybean protein is hydrolyzed by protease, inactivated, and then filtered to obtain the soybean oligopeptides.

[0039] Furthermore, the protease is a complex enzyme of Alcalase and Flavorzyme, with an enzyme activity ratio of 2:1 and an addition amount of 2%-3%.

[0040] Furthermore, the enzymatic hydrolysis conditions are: pH = 7-8.5, temperature = 50-60℃, and time = 4-5h.

[0041] In a specific embodiment, the preparation method of the soybean oligopeptide includes the following steps:

[0042] Soybean protein is enzymatically hydrolyzed with a complex enzyme of Alcalase and Flavorzyme (enzyme activity ratio of 2:1, addition amount of 2%-3%) at pH=7-8.5 and 50-60℃ for 4-5 hours, and then decomposed by ultrasound. After inactivation, the protein is passed through a 5kDa ultrafiltration membrane to retain small molecule peptides and remove unhydrolyzed macromolecular impurities, thus obtaining the soybean oligopeptide.

[0043] Furthermore, the animal-derived oligopeptide is a fish protein oligopeptide.

[0044] Furthermore, the fish protein oligopeptide is prepared by the following method: fish surimi is centrifuged and defatted, then hydrolyzed with protease, filtered, and dried to obtain the fish protein oligopeptide.

[0045] Furthermore, the protease is flavorzyme and trypsin, wherein the amount of flavorzyme added is 1%-1.5% and the amount of trypsin added is 0.5%-1%.

[0046] Furthermore, the enzymatic hydrolysis conditions are: pH = 7.0-7.5, temperature = 50-55℃, and time = 6-7h.

[0047] In a specific embodiment, the preparation method of the fish protein oligopeptide includes the following steps:

[0048] After soaking in sodium bicarbonate solution, the fish surimi was centrifuged to remove fat. The fish surimi was then enzymatically hydrolyzed with flavorzyme (1%-1.5%) and trypsin (0.5%-1%) at pH 7.0-7.5 and 50-55℃ for 6-7 hours. After ultrafiltration through a 1kDa membrane, the fish surimi was spray-dried to obtain the fish protein oligopeptide.

[0049] Furthermore, the bioactive alkaloid is selected from at least two of betaine, seaweed alkaloid, and choline.

[0050] Furthermore, when the bioactive alkaloid is betaine and alginate, the mass ratio of betaine to alginate is 1:(0.5-2), and the total content is 0.1%-1.5%.

[0051] Furthermore, the alkaloid purity of the beet is ≥98%; the seaweed alkaloid is extracted from *Alternaria solani*.

[0052] Furthermore, when the bioactive alkaloid is betaine and choline, the mass ratio of betaine to choline is 1:(1-3), and the total content is 0.2%-1.5%.

[0053] Furthermore, the choline is added in the form of choline chloride with a purity of ≥95%.

[0054] Furthermore, when the bioactive alkaloid is betaine, alginate, and choline, the mass ratio of betaine, alginate, and choline is 1:(0.5-1.5):(1-2), and the total content is 0.5%-1.8%.

[0055] Furthermore, the functional microbial agent is a compound agent of Bacillus subtilis and Bacillus mucilaginosa, with a viable count ratio of 1:(1.5-3); the effective viable count is ≥5×10⁻⁶. 8 CFU / g.

[0056] Furthermore, the pH adjuster is potassium dihydrogen phosphate citrate buffer, and the pH value of the potassium dihydrogen phosphate citrate buffer is 6.0-7.5.

[0057] Furthermore, the concentration of the pH adjuster is 0.1-0.5 mol / L.

[0058] Furthermore, the stabilizer is sodium polyaspartate.

[0059] In this invention, modified chitosan oligosaccharide (phenolic acid grafted) and complex oligopeptides form nanomicelles, enhancing leaf surface penetration and root absorption; functional microbial agents (Bacillus subtilis + Bacillus spp.) and modified chitosan oligosaccharide jointly activate soil enzyme activity; amidated pectin / corn cob composite carrier enables phased nutrient release, and in conjunction with a drip irrigation system, extends the fertilizer effect cycle.

[0060] The second aspect of this invention provides a method for preparing the quaternary synergistic water-soluble fertilizer synergist described in the first aspect, comprising the following steps:

[0061] (1) Mix the modified chitosan oligosaccharide with water and add a pH adjuster to obtain a modified chitosan oligosaccharide solution;

[0062] (2) Add plant-derived oligopeptides, animal-derived oligopeptides and bioactive base to the modified chitosan oligosaccharide solution obtained in step (1), and use ultrasonic treatment to form a micelle complex with a particle size ≤200nm.

[0063] (3) Mix amino acid chelated trace elements and alkali-modified humic acid to obtain a composite chelate solution; adsorb the above composite chelate solution onto a slow-release carrier to a loading rate of ≥85% to obtain an auxiliary synergistic component.

[0064] (4) The compound agent of Bacillus subtilis and Bacillus colloidis is reconstituted with water to obtain the functional microbial agent solution. The resulting solution is then mixed with the auxiliary synergistic component obtained in step (3) to obtain the auxiliary synergistic solution of the functional microbial agent.

[0065] (5) Mix the micelle complex obtained in step (2) with the auxiliary synergist of the functional microbial agent obtained in step (4), add a stabilizer, and perform homogenization to obtain the quaternary synergistic water-soluble fertilizer synergist.

[0066] The water-soluble fertilizer synergist provided by this invention comprises modified chitosan oligosaccharide, plant and animal-derived oligopeptides, bioactive alkali, functional microbial agents, and slow-release carriers, and is prepared through molecular structure modification, ultrasonic-assisted compounding, and vacuum loading processes.

[0067] Further, in step (1), the modified chitosan oligosaccharide is mixed with deionized water at a mass ratio of 1:(10-20) at 40-50℃.

[0068] Further, in step (2), the molecular weight of the plant-derived oligopeptide is ≤5000 Da, and the molecular weight of the animal-derived oligopeptide is ≤5000 Da.

[0069] Further, in step (2), the conditions for ultrasonic treatment are: frequency of 20-40kHz, power density of 30-60W / L, and time of 10-15min.

[0070] Further, in step (3), the amino acid chelated trace elements are glutamic acid chelated boron, glycine chelated iron and proline chelated zinc, and the mass ratio of glutamic acid chelated boron, glycine chelated iron and proline chelated zinc is (2-4):(1-3):1.

[0071] Further, in step (3), the pH is adjusted to 7.0-7.5 after the amino acid chelated trace elements and alkali-modified humic acid are mixed.

[0072] Furthermore, in step (3), the reaction conditions are: reacting at 50-60℃ for 1-2 hours.

[0073] Furthermore, in step (3), the sustained-release carrier is prepared by mixing amidated pectin with corn cob particles.

[0074] Further, in step (4), the compound bacterial agent is reconstituted with water at a mass ratio of 1:(4-6).

[0075] Further, in step (4), the bacterial agent solution and the auxiliary synergistic component are mixed at a mass ratio of 1:(2-4) and adsorbed under a vacuum of -0.08MPa for 20-30 minutes, and the bacterial agent survival rate is ≥95%.

[0076] In a specific embodiment, the preparation method of the quaternary synergistic water-soluble fertilizer synergist includes the following steps:

[0077] (1) Pre-dissolution of modified chitosan oligosaccharide: Mix modified chitosan oligosaccharide with deionized water at 40-50℃ at a mass ratio of 1:(10-20); add 0.1%-0.5% citrate-dipotassium hydrogen phosphate buffer (pH=6.0-7.5, concentration 0.1-0.5mol / L), stir at 200-300r / min for 15-20min until completely dissolved to obtain modified chitosan oligosaccharide solution.

[0078] (2) Oligopeptide and bioactive base compound: Plant-derived oligopeptide (molecular weight ≤5000Da), animal-derived oligopeptide (molecular weight ≤5000Da), and bioactive base are added sequentially to the modified chitosan oligosaccharide solution; ultrasonic dispersion (frequency 20-40kHz, power density 30-60W / L) is used for 10-15min to form a micelle complex with a particle size ≤200nm.

[0079] (3) Compounding of auxiliary synergistic components: Mix amino acid chelated trace elements (glutamic acid chelated boron: glycine chelated iron: proline chelated zinc = (2-4):(1-3):1) and alkali-modified humic acid (pH = 8-9 treatment) in a certain proportion, adjust the pH to 7.0-7.5, react at 50-60℃ for 1-2 hours, filter through a 0.45μm membrane to obtain a composite chelate solution; mix amidated pectin (porosity 60-70%) with corn cob particles (particle size 0.3-0.8mm) in a 1:1 ratio, adsorb the above composite chelate solution to a loading rate ≥85% to obtain auxiliary synergistic components.

[0080] (4) Integration of microbial agents: A compound agent of Bacillus subtilis and Bacillus mucilaginosa (live count ≥ 5 × 10⁻⁶) 8 The functional microbial agent solution was obtained by reconstituted CFU / g with deionized water at a mass ratio of 1:(4-6); the functional microbial agent solution was mixed with the auxiliary synergist at a mass ratio of 1:(2-4) and adsorbed under a vacuum of -0.08MPa for 20-30 min. The survival rate of the microbial agent was ≥95%, thus obtaining the auxiliary synergist solution of the functional microbial agent.

[0081] (5) Final product preparation: Mix the micelle complex obtained in step (2) with the auxiliary synergist of the functional microbial agent obtained in step (4), add sodium polyaspartate as a stabilizer, process it with a high-pressure homogenizer (50MPa, 3 cycles), and package it into a clear water agent to obtain the quaternary synergistic water-soluble fertilizer synergist.

[0082] The third aspect of this invention provides the application of the quaternary synergistic water-soluble fertilizer enhancer described in the first aspect in chemical fertilizers.

[0083] Furthermore, the quaternary synergistic water-soluble fertilizer enhancer is compounded with water-soluble fertilizer at a volume ratio of 1:50-200 and applied.

[0084] Furthermore, the application methods include drip irrigation, fertigation, foliar spraying, etc.

[0085] The beneficial effects of this invention are:

[0086] (1) This invention is based on a four-dimensional synergistic mechanism of chitosan oligosaccharide-oligopeptide-bioactive alkali-functional microbial agents, achieving deep coupling of chemical growth promotion, biological activation and physical slow release, as well as multi-component synergistic effect and efficient nutrient utilization. Among them, modified chitosan oligosaccharide enhances chelating ability through molecular structure optimization, forming a nanoscale composite system with oligopeptides, significantly improving the absorption and translocation efficiency of nutrients on leaves and roots. Functional microbial agents and chitosan oligosaccharide synergistically activate soil enzyme activity, promote the release of insoluble phosphorus and potassium, significantly improve nitrogen, phosphorus and potassium utilization rate compared with traditional fertilizers, and effectively reduce nutrient loss.

[0087] (2) The bioactive alkali provided by this invention significantly improves the survival rate and water use efficiency of crops under stress environments such as salinity, drought and alkali through osmotic regulation and gene activation mechanisms. At the same time, phenolic acid grafted chitosan oligosaccharide exhibits broad-spectrum antibacterial activity, which can effectively inhibit the infection of soil-borne pathogens, reduce dependence on chemical pesticides, and provide dual protection for the healthy growth of crops, thereby enhancing the crop's stress resistance and disease control capabilities.

[0088] (3) This invention employs a natural, biodegradable, slow-release carrier combined with directional adsorption technology to ensure high survival rates and field colonization efficiency of functional microbial agents during storage and application. The metabolites of the agents work synergistically with alkali-modified humic acid to neutralize soil acidity, reduce the risk of salinization, and promote the formation of soil aggregates, thereby achieving continuous improvement in soil organic matter content and microecological balance, as well as long-term maintenance of microbial activity and soil health restoration.

[0089] (4) The quaternary synergistic water-soluble fertilizer enhancer provided by the present invention has strong compatibility and can be directly compounded with commercially available water-soluble fertilizers. It is suitable for diverse planting scenarios of facility agriculture, field crops and cash crops, and has the potential for large-scale promotion. Attached Figure Description

[0090] Figure 1 The flowchart for the preparation of a quaternary synergistic water-soluble fertilizer enhancer in Example 1 is shown. Detailed Implementation

[0091] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0092] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0093] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0094] In the following examples, the modified chitosan oligosaccharide was prepared by the following method:

[0095] a) Preparation of chitosan oligosaccharides: Using crustacean shells as raw materials, after decalcification by acid treatment (HCl concentration of 2 mol / L, temperature of 80℃), chitosan (degree of deacetylation ≥90%) is prepared by enzymatic hydrolysis. The chitosan is then degraded in a hydrogen peroxide-ascorbic acid composite degradation system (H2O2 concentration of 5%, ascorbic acid addition of 0.1%, temperature of 50℃) for 2 hours to obtain chitosan oligosaccharides with a molecular weight of 1000-5000 Da.

[0096] b) Phenolic acid activation: Phenolic acid is dissolved in a polar solvent (dimethyl sulfoxide buffer), and an activator (EDC / NHS composite system (molar ratio of 1:1, the total amount of activator is 1 times the molar amount of phenolic acid) is added and activated at 30°C for 2 hours to obtain an activated phenolic acid solution; the phenolic acid is selected from gallic acid.

[0097] c) Grafting reaction: The chitosan oligosaccharide obtained in step a) was added to the activated phenolic acid solution, and the molar ratio of chitosan oligosaccharide to phenolic acid was controlled at 1:0.5. The reaction was carried out at 40℃ for 6 hours. During the reaction, the directional grafting of amino / hydroxyl groups was promoted by ultrasound assistance (frequency 20kHz, power density 50W / L) to obtain the grafted product.

[0098] d) Purification: After the reaction, the grafted product was precipitated with anhydrous ethanol, and unreacted monomers were removed by filtration through a 0.45 μm membrane. Then, the modified chitosan oligosaccharide (gallic acid grafted chitosan oligosaccharide) was obtained by spray drying.

[0099] In the following examples, soybean oligopeptides were prepared by the following method: soybean protein was enzymatically hydrolyzed with a complex enzyme of Alcalase and Flavorzyme (enzyme activity ratio of 2:1, addition amount of 2%) at pH=7-8.5 and 50-60℃ for 4 hours, and then decomposed by ultrasound to accelerate the decomposition. After inactivation, the oligopeptides were obtained by passing the enzyme through a 5kDa ultrafiltration membrane to retain small molecule peptides and remove unhydrolyzed macromolecular impurities.

[0100] In the following examples, the cod protein oligopeptide was prepared by the following method: cod surimi was soaked in sodium bicarbonate solution and then centrifuged to remove fat. The cod surimi was then enzymatically hydrolyzed with flavorzyme (1.5%) and trypsin (0.5%) at pH 7.0 and 50°C for 6 hours. After ultrafiltration through a 1kDa membrane, the cod protein oligopeptide was obtained by spray drying.

[0101] Example 1

[0102] A quaternary synergistic water-soluble fertilizer synergist, comprising the following components by mass percentage: modified chitosan oligosaccharide (gallic acid grafted, grafting rate 38%): 1.2%; plant-derived oligopeptide (soybean oligopeptide, molecular weight 1500 Da): 4.5%; animal-derived oligopeptide (cod protein oligopeptide, molecular weight 800 Da): 1.0%; bioactive alkaloid (betaine: seaweed alkaloid = 1:1, purity ≥98%): 0.8%; functional microbial agent (Bacillus subtilis: Bacillus spp. = 1:2, viable count 6 × 10⁻⁶). 8 CFU / g): 1.5%; Amino acid chelated trace elements (glycine chelated iron, proline chelated zinc, glutamic acid chelated boron): 1.2%; Alkali-modified humic acid (carboxyl content 4.5 mmol / g): 4.0%; Slow-release carrier (amidated pectin: corn cob = 1:1, loading rate 88%): 3.5%; Potassium dihydrogen phosphate citrate buffer (pH = 6.8): 0.3%; Sodium polyaspartate: 0.05%; Balance: deionized water.

[0103] Example 1: Flowchart for preparing a quaternary synergistic water-soluble fertilizer enhancer is as follows Figure 1 As shown, the preparation method includes the following steps:

[0104] (1) Pre-dissolution of modified chitosan oligosaccharide: Mix 1.2 kg of modified chitosan oligosaccharide with 12 L of 45℃ deionized water at a mass ratio of 1:10; add 0.3 kg of potassium dihydrogen phosphate citrate buffer (pH = 6.8, concentration 0.1 mol / L), stir at 250 r / min for 18 min until completely dissolved to obtain modified chitosan oligosaccharide solution.

[0105] (2) Oligopeptide and bioactive alkali compound: 4.5 kg soybean oligopeptide, 1.0 kg cod protein oligopeptide and 0.8 kg bioactive alkali (betaine: seaweed alkali = 1:1) were added to the modified chitosan oligosaccharide solution in sequence; ultrasonic dispersion (frequency 40 kHz, power density 60 W / L) was used for 12 min to form a micelle complex with a particle size of 180 nm.

[0106] (3) Compounding of auxiliary synergistic components: 1.2 kg of amino acid chelated trace elements (glutamic acid chelated boron: glycine chelated iron: proline chelated zinc = 2:1:1) and 4 kg of alkali-modified humic acid (pH = 7.2 treatment) were mixed, the pH was adjusted to 7.2, and the mixture was reacted at 55℃ for 2 h. The mixture was then filtered through a 0.45 μm membrane to obtain a composite chelate solution. Amidated pectin (porosity 60%) and corn cob particles (particle size 0.3 mm) were mixed at a ratio of 1:1 to obtain 3.5 kg of slow-release carrier. The above composite chelate solution was adsorbed to a loading rate of 88% to obtain auxiliary synergistic components.

[0107] (4) Integration of microbial agents: 1.5 kg of Bacillus subtilis and Bacillus spp. were reconstituted with 7.5 L of deionized water to obtain a functional microbial agent solution; the functional microbial agent solution was mixed with the auxiliary synergistic component at a mass ratio of 1:2 and adsorbed under a vacuum of -0.08 MPa for 30 min. The survival rate of the agent was 96.7%, and the auxiliary synergistic solution of the functional microbial agent was obtained.

[0108] (5) Final product preparation: Mix the micelle complex obtained in step (2) with the auxiliary synergist of the functional microbial agent obtained in step (4), add 0.05 kg of sodium polyaspartate as a stabilizer, process by a high-pressure homogenizer (50 MPa, 3 cycles), and package into a clear water agent to obtain the quaternary synergistic water-soluble fertilizer synergist.

[0109] Application Example 1 (Tomato Cultivation Application)

[0110] Tested variety: Tomato;

[0111] Experimental location: Jiaxing City, Zhejiang Province; continuous cropping for 3 years; basic soil properties: pH = 5.6, EC (electrical conductivity) = 3.2 dS / m, organic matter content = 1.8%;

[0112] Comparison fertilizer: Commercially available humic acid water-soluble fertilizer (N-P2O5-K2O=20-10-20, humic acid content 8%).

[0113] Experimental treatment:

[0114] Treatment group: commercially available humic acid water-soluble fertilizer (N 180kg / ha) + quaternary synergistic water-soluble fertilizer enhancer of Example 1 (the volume ratio of quaternary synergistic water-soluble fertilizer enhancer to commercially available humic acid water-soluble fertilizer is 1:100), applied by drip irrigation, fertilized 5 times throughout the growth period.

[0115] Control group 1: Full-grain fertilizer (N 300kg / ha, no synergist), applied by drip irrigation, 5 times throughout the growth period;

[0116] Control group 2: Commercially available humic acid water-soluble fertilizer (N 180kg / ha) + commercially available humic acid synergist (the volume ratio of commercially available humic acid synergist to commercially available humic acid water-soluble fertilizer is 1:100, and the main component of commercially available humic acid synergist is mineral-derived potassium fulvate), applied by drip irrigation, fertilized 5 times throughout the entire growth period.

[0117] Repetition settings: Randomized block design, 3 repetitions, cell area 30m² 2 .

[0118] Experimental results:

[0119] 1. The effects of increased output and improved quality are shown in Table 1:

[0120] Table 1. Yield per mu and single fruit weight of treatment group, control group 1, and control group 2.

[0121] deal with Yield per mu (kg) Weight of a single fruit (g) Processing group 6850±210 185±6 Control group 1 5600±180 152±5 Control group 2 6050±195 168±5

[0122] Compared with the control group 1, the treatment group increased yield by 22.3%, and the nitrogen fertilizer partial productivity (PFP) reached 38.1 kg / kg, an increase of 51.9%.

[0123] 2. The effects on disease resistance and soil improvement are shown in Table 2:

[0124] Table 2. Incidence of bacterial wilt, soil pH, and available phosphorus content in the treatment group, control group 1, and control group 2.

[0125] deal with Incidence rate of bacterial wilt (%) Soil pH Available phosphorus content (mg / kg) Processing group 8.5±1.2 6.1±0.2 45.3±3.1 Control group 1 23.6±2.5 5.6±0.3 28.7±2.4 Control group 2 15.4±1.8 5.8±0.2 36.2±2.7

[0126] Modified chitosan oligosaccharide inhibited biofilm formation in Ralstonia solanacearum (CLSM observation); the phosphorus solubilizing activity of Bacillus thuringiensis reached 12.7 μg / (g·h), and the available phosphorus content was increased by 57.8%.

[0127] Example 2

[0128] A quaternary synergistic water-soluble fertilizer synergist, comprising the following components by mass percentage: modified chitosan oligosaccharide (gallic acid grafted, grafting rate 38%): 2.0%; plant-derived oligopeptide (soybean oligopeptide, molecular weight 1500 Da): 5.0%; animal-derived oligopeptide (cod protein oligopeptide, molecular weight 800 Da): 2.0%; bioactive alkaloid (betaine:alginic acid:choline = 1:1:1.5, purity ≥98%): 1.8%; functional microbial agent (Bacillus subtilis: Bacillus spp. = 1:3, viable count 6 × 10⁻⁶). 8 CFU / g): 2.0%; Amino acid chelated trace elements (glycine chelated iron, proline chelated zinc, glutamic acid chelated boron): 2.0%; Alkali-modified humic acid (carboxyl content 4.5 mmol / g): 5.0%; Slow-release carrier (amidated pectin: corn cob = 1:1, loading rate 90%): 3.5%; Potassium dihydrogen phosphate citrate buffer (pH = 6.8): 0.2%; Sodium polyaspartate: 0.1%; Balance: deionized water.

[0129] The preparation method of the quaternary synergistic water-soluble fertilizer synergist in Example 2 includes the following steps:

[0130] (1) Pre-dissolution of modified chitosan oligosaccharide: Mix 2.0 kg of modified chitosan oligosaccharide with 30 L of 45℃ deionized water at a mass ratio of 1:15; add 0.2 kg of potassium dihydrogen phosphate citrate buffer (pH = 6.8, concentration 0.1 mol / L), stir at 200 r / min for 20 min until completely dissolved to obtain modified chitosan oligosaccharide solution.

[0131] (2) Oligopeptide and bioactive alkali compound: 5.0 kg soybean oligopeptide, 2.0 kg cod protein oligopeptide and 1.8 kg bioactive alkali (betaine:algin:choline = 1:1:1.5) were added sequentially to the modified chitosan oligosaccharide solution; ultrasonic dispersion (frequency 40 kHz, power density 60 W / L) was performed for 15 min to form a micelle complex with a particle size of 180 nm.

[0132] (3) Compounding of auxiliary synergistic components: 2.0 kg of amino acid chelated trace elements (glutamic acid chelated boron: glycine chelated iron: proline chelated zinc = 2:3:1) and 5.0 kg of alkali-modified humic acid (pH = 7.2 treatment) were mixed, the pH was adjusted to 7.2, and the mixture was reacted at 55℃ for 2 h. The mixture was then filtered through a 0.45 μm membrane to obtain a composite chelate solution. Amidated pectin (porosity 70%) and corn cob particles (particle size 0.8 mm) were mixed at a ratio of 1:1 to obtain 3.5 kg of slow-release carrier. The above composite chelate solution was adsorbed to a loading rate of 90% to obtain auxiliary synergistic components.

[0133] (4) Integration of microbial agents: 2.0 kg of Bacillus subtilis and Bacillus spp. were reconstituted with 10 L of deionized water to obtain an agent solution; the agent solution was mixed with a slow-release carrier at a mass ratio of 1:4 and adsorbed under a vacuum of -0.08 MPa for 30 min. The survival rate of the agent was 98.0%, and an auxiliary synergistic solution for functional microbial agents was obtained.

[0134] (5) Final product preparation: Mix the micelle complex obtained in step (2) with the auxiliary synergist of the functional microbial agent obtained in step (4), add 0.1 kg of sodium polyaspartate as a stabilizer, process by a high-pressure homogenizer (50 MPa, 3 cycles), and package into a clear water agent to obtain the quaternary synergistic water-soluble fertilizer synergist.

[0135] Application Example 2 (Rice Application in Saline-Alkali Land)

[0136] Tested variety: Salt-tolerant rice No. 12;

[0137] Experimental location: Dafeng District, Yancheng City, Jiangsu Province; soil type: coastal saline soil; basic soil properties: pH=5.8, EC=4.6dS / m, total salt content: 0.38%, organic matter content: 0.9%;

[0138] Comparison fertilizer: Commercially available humic acid water-soluble fertilizer (N-P2O5-K2O=20-10-20, humic acid content 8%).

[0139] Experimental treatment:

[0140] Treatment group: commercially available humic acid water-soluble fertilizer (N 210kg / ha) + quaternary synergistic water-soluble fertilizer enhancer of Example 1 (the volume ratio of quaternary synergistic water-soluble fertilizer enhancer to commercially available humic acid water-soluble fertilizer is 1:150), with alternating dry and wet irrigation;

[0141] Control group 1: Full-grain fertilizer (N 300kg / ha, no synergist), irrigation with alternating dry and wet conditions;

[0142] Control group 2: Commercially available humic acid water-soluble fertilizer (N 210 kg / ha) + commercially available microbial fertilizer (volume ratio of commercially available microbial fertilizer to commercially available humic acid water-soluble fertilizer 1:150, 5×10 8 CFU / g, the main microbial strain in commercially available microbial fertilizers is Bacillus subtilis), and irrigation should be carried out alternately with dry and wet conditions;

[0143] Irrigation system: Maintain a water layer of 3-5 cm during the tillering stage, and alternate between dry and wet conditions during the heading stage (soil moisture content 60%-70%).

[0144] Experimental results:

[0145] 1. The effects of yield and stress resistance are shown in Table 3:

[0146] Table 3. Effective spike number, number of grains per spike, thousand-grain weight, proline content, and SOD activity of the treatment group, control group 1, and control group 2.

[0147]

[0148]

[0149] The yield of the treatment group reached 510 kg / mu, which was 37.8% higher than that of the control group 1, and the number of grains per ear increased by 20.5%. The proline content decreased by 26.3%, and the SOD activity increased by 33.8%, indicating that the salt stress damage was significantly alleviated.

[0150] 2. The soil improvement effects are shown in Table 4:

[0151] Table 4. Soil EC, soil pH, and microbial Shannon index of treatment group, control group 1, and control group 2.

[0152]

[0153] Alkali-modified humic acid reduces Na+ through ion exchange. + Adsorption capacity was 31.4%; the functional bacterial agent increased the abundance of Halomonas by 3.2 times and enhanced the salt tolerance metabolic pathway.

[0154] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art should understand that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A quaternary synergistic water-soluble fertilizer enhancer, characterized in that, The quaternary synergistic water-soluble fertilizer enhancer is composed of the following components in the following mass percentages: modified chitosan oligosaccharide 0.5%-3%, plant-derived oligopeptides 1.5%-6%, animal-derived oligopeptides 0.5%-2%, bioactive alkali 0.1%-1.8%, functional microbial agent 0.8%-2%, auxiliary synergistic components 5%-12%, pH adjuster 0.1%-0.5%, stabilizer 0.01%-0.1%, and the balance being water; The modified chitosan oligosaccharide is a phenolic acid-grafted chitosan oligosaccharide; the auxiliary synergistic components include amino acid chelated trace elements, alkali-modified humic acid, and a sustained-release carrier.

2. The quaternary synergistic water-soluble fertilizer enhancer according to claim 1, characterized in that, The quaternary synergistic water-soluble fertilizer enhancer is composed of the following components by mass percentage: modified chitosan oligosaccharide 0.5%-3%, plant-derived oligopeptides 1.5%-6%, animal-derived oligopeptides 0.5%-2%, bioactive alkali 0.1%-1.8%, functional microbial agent 0.8%-2%, amino acid chelated trace elements 0.5%-2%, alkali-modified humic acid 3%-5%, slow-release carrier 1.5%-5%, pH adjuster 0.1%-0.5%, stabilizer 0.01%-0.1%, and the balance being water.

3. The quaternary synergistic water-soluble fertilizer enhancer according to claim 1, characterized in that, The amino acid chelated trace elements include glycine chelated iron, proline chelated zinc, and glutamic acid chelated boron, with a chelation degree ≥90%. The alkali-modified humic acid is prepared from lignite through alkali modification, with a carboxyl content ≥4.2 mmol / g and a water solubility ≥95%. The slow-release carrier includes amidated pectin and corn cob particles, with an esterification degree ≥70% and a porosity of 60-70%. The corn cob particles have a particle size of 0.3-0.8 mm.

4. The quaternary synergistic water-soluble fertilizer enhancer according to claim 1, characterized in that, The modified chitosan oligosaccharide was prepared by the following method: a) Chitosan was prepared by using the shells of crustaceans as raw materials, after acid treatment and decalcification, and then by enzymatic hydrolysis. b) Dissolve phenolic acid in a polar solvent, add an activator to obtain an activated phenolic acid solution; the phenolic acid is selected from at least one of gallic acid, p-coumaric acid and protocatechuic acid, and the molar ratio of phenolic acid to activator is 1:(1-3); c) Add the chitosan oligosaccharide obtained in step a) to the activated phenolic acid solution, wherein the molar ratio of chitosan oligosaccharide to phenolic acid is 1:(0.5-2), and the reaction yields the grafted product; d) The grafted product was precipitated with an organic solvent, unreacted monomers were removed by filtration, and the modified chitosan oligosaccharide was obtained by spray drying.

5. The quaternary synergistic water-soluble fertilizer enhancer according to claim 1, characterized in that, The plant-derived oligopeptide is a soybean oligopeptide; the animal-derived oligopeptide is a fish protein oligopeptide; and the bioactive alkaloid is selected from at least two of betaine, seaweed alkaloid, and choline.

6. The quaternary synergistic water-soluble fertilizer enhancer according to claim 1, characterized in that, The functional microbial agent is a compound agent of Bacillus subtilis and Bacillus mucilaginosa, with a viable count ratio of 1:(1.5-3); the effective viable count is ≥5×10⁻⁶. 8 CFU / g.

7. The quaternary synergistic water-soluble fertilizer enhancer according to claim 1, characterized in that, The pH adjuster is potassium dihydrogen phosphate citrate buffer, and the pH value of the potassium dihydrogen phosphate citrate buffer is 6.0-7.

5.

8. A method for preparing a quaternary synergistic water-soluble fertilizer enhancer according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Mix the modified chitosan oligosaccharide with water and add a pH adjuster to obtain a modified chitosan oligosaccharide solution; (2) Add plant-derived oligopeptides, animal-derived oligopeptides and bioactive alkali to the modified chitosan oligosaccharide solution obtained in step (1), and use ultrasonic treatment to form a micelle complex with a particle size ≤200nm. (3) Mix amino acid chelated trace elements and alkali-modified humic acid to obtain a composite chelate solution; adsorb the above composite chelate solution onto a slow-release carrier to a loading rate ≥85% to obtain an auxiliary synergistic component; (4) The compound agent of Bacillus subtilis and Bacillus colloidis is reconstituted with water to obtain the functional microbial agent solution. The resulting solution is then mixed with the auxiliary synergistic component obtained in step (3) to obtain the auxiliary synergistic solution of the functional microbial agent. (5) Mix the micelle complex obtained in step (2) with the auxiliary synergist of the functional microbial agent obtained in step (4), add a stabilizer, and perform homogenization to obtain the quaternary synergistic water-soluble fertilizer synergist.

9. The application of the quaternary synergistic water-soluble fertilizer enhancer according to any one of claims 1-7 in chemical fertilizers.

10. The application according to claim 9, characterized in that, The quaternary synergistic water-soluble fertilizer enhancer is mixed with water-soluble fertilizer at a volume ratio of 1:50-200 and applied.

Images