Wheat zinc selenium bio-organic foliar fertilizer and preparation method thereof

Abstract

The present application relates to the technical field of wheat bio-organic foliar fertilizer, and discloses a wheat zinc-selenium bio-organic foliar fertilizer and a preparation method thereof, which comprises: 300-400 parts of fermentation substrate, 40-60 parts of zinc sulfate, 2-5 parts of sodium selenite, 15-25 parts of alginic acid extract, 80-120 parts of compound amino acid, 1-2 parts of potassium sorbate and 435-554 parts of water. The present application combines zinc-selenium nutrient fortification with the biological stimulation of alginic acid extract, compound amino acid and fermentation substrate. The alginic acid extract can promote the growth of wheat root system, improve the photosynthetic efficiency of leaves and enhance the drought resistance and disease resistance of wheat. The compound amino acid can be directly absorbed and utilized by wheat, supplement the raw materials for protein synthesis and improve the quality of grains. The organic matter and beneficial bacteria metabolites in the fermentation substrate can regulate the growth rhythm of wheat, promote nutrient transport, and achieve the effect of trinity of wheat nutrient fortification, stress resistance enhancement and yield increase.

Description

Technical Field

[0001] This invention relates to the field of wheat bio-organic foliar fertilizer technology, and more specifically, to a wheat zinc-selenium bio-organic foliar fertilizer and its preparation method. Background Technology

[0002] Wheat is currently the world's most widely cultivated, distributed, and productive food crop, with the highest trade volume. In developing countries, wheat products provide approximately 50% of calories and 20-25% of zinc. In my country, wheat is the third largest food crop, with its planting area and total output second only to corn and rice. Winter wheat production in the North China Plain accounts for about 70% of the country's total wheat production. Wheat production plays a vital role in ensuring national food security and improving people's living standards.

[0003] Zinc and selenium are key trace elements for maintaining health, playing irreplaceable roles in both human and plant growth. Zinc is the active center of many enzymes in the human body, participating in DNA synthesis, immune function, and children's growth and development, while also maintaining taste and wound healing. Selenium, as a core component of glutathione peroxidase, has strong antioxidant capabilities, protecting cells from free radical damage and supporting thyroid function and immune regulation. In plants, zinc is essential for chlorophyll synthesis, hormone metabolism, and seed development; zinc deficiency leads to yellowing leaves and stunted growth. Selenium, on the other hand, enhances plant stress resistance by strengthening antioxidant enzyme systems, and adequate intake promotes photosynthesis and nutrient absorption.

[0004] With improvements in planting varieties and techniques, my country's wheat yield has greatly increased. However, the micronutrient quality of wheat grains has shown a downward trend. The zinc content in wheat grains is generally below 25 mg / kg, and the selenium content is less than 0.05 mg / kg, far below the standards for zinc enrichment (≥40 mg / kg) and selenium enrichment (≥0.1 mg / kg). Therefore, improving the zinc and selenium content of wheat grains through agronomic measures is crucial for crop growth and plays an important role in improving human health. Traditional soil fertilization methods for supplementing zinc and selenium have significant drawbacks: under alkaline conditions (pH > 7), zinc easily forms insoluble ZnCO3 precipitate with carbonates, while selenium is oxidized to poorly absorbed SeO3. 2- form.

[0005] While foliar spraying can bypass soil barriers, existing foliar fertilizer technologies face three major technical bottlenecks: 1) Limited improvement in zinc and selenium content: Many foliar fertilizers significantly increase selenium content in grains, but still fall short of meeting the zinc content (45 mg / kg) required for human biofortification. It is necessary to increase the amount of zinc fertilizer in foliar fertilizers to improve zinc nutrition in wheat grains. 2) Carrier compatibility defects: Traditional EDTA chelating agents have poor compatibility with Zn at pH > 6.2+ The stability constant of zinc selenide decreases, leading to competitive chelation with selenate and a precipitation rate of over 35% within 48 hours in the mixed system. Commercially available products mostly employ physical mixing processes, lacking a synergistic stabilization mechanism at the molecular level. Zinc selenium ions easily crystallize and precipitate during leaf drying, resulting in an actual adhesion rate of less than 40%. 3) Limitations of single function: Current products focus only on nutritional fortification, neglecting the synergistic needs of wheat stress resistance and yield improvement.

[0006] Therefore, the present invention proposes a zinc-selenium bio-organic foliar fertilizer for wheat and its preparation method, which has important practical significance. Summary of the Invention

[0007] In view of this, the present invention proposes a wheat zinc-selenium bio-organic foliar fertilizer and its preparation method, aiming to solve at least one of the problems in the above-mentioned background technology.

[0008] This invention proposes a wheat zinc-selenium bio-organic foliar fertilizer, comprising the following components in parts by weight: The components include the following parts by mass: The fermentation substrate consists of 300-400 parts, zinc sulfate 40-60 parts, sodium selenite 2-5 parts, alginate extract 15-25 parts, compound amino acids 80-120 parts, potassium sorbate 1-2 parts, and water 435-554 parts.

[0009] Furthermore, the preparation method of the alginate extract is as follows: After rinsing the *Tetracentron sinense* three times with water, dry it at 60℃ for 8 hours. After drying, pulverize it to 20-40 mesh to obtain *Tetracentron sinense* powder. Add the *Alternaria buergeriana* powder to water at a ratio of 1g:20ml, stir, then add 1% (by weight) of the compound enzyme preparation to the water. Adjust the pH of the system to between 4.8 and 5.2, and then enzymatically hydrolyze the mixture at 55℃ with a stirring speed of 150r / min for 4.5h to obtain the enzymatic hydrolysate. The enzymatic hydrolysate was heated to 90°C and kept at that temperature for 15 minutes. After cooling, it was filtered under a pressure of 0.2 MPa. The filtrate was collected and filtered through a 1 μm filter membrane to obtain the crude extract. Add 2 times the volume of ethanol to the crude extract, stir and let stand for 24 hours. Then centrifuge at 4000 r / min for 15 min, collect the precipitate, wash the precipitate twice with ethanol, and then add the precipitate to water at a ratio of 1 g: 15 ml of precipitate to water and stir to dissolve. Then spray dry to obtain alginate extract. The compound enzyme preparation is formulated with cellulase and pectinase in a mass ratio of 3:1.

[0010] Furthermore, the preparation method of the complex amino acid is as follows: Take soybean meal, grind it to a particle size of 40-60 mesh, and then sterilize it at 121℃ for 20 minutes to obtain sterilized soybean meal; Sterilized soybean meal was added to water at a ratio of 1g:1.5ml, stirred, and then inoculated with a compound fermentation agent containing 2.5% of sterilized soybean meal plasmid. The mixture was then incubated at 35℃ and 0.6ml. 3 / (m 3 Aerobic fermentation was carried out at an aeration rate of ·h for 72h. After the fermentation, 0.5% by weight of neutral protease of the fermentation product was added to adjust the pH of the system to between 6.5 and 7.0. Enzymatic hydrolysis was carried out at 50℃ and 200r / min for 2h. Then, the temperature was raised to 85℃ and held for 10min. After cooling to room temperature, the mixture was filtered at a pressure of 0.3MPa. 0.3% by weight of activated carbon was added to the filtrate and decolorized at 60℃ for 30min. The activated carbon was then removed by filtration. The filtrate was concentrated under reduced pressure at -0.09MPa and 65℃ for 3h to obtain the complex amino acids.

[0011] Furthermore, the preparation method of the fermentation substrate is as follows: Peanut cake powder, corn stalk powder, and soybean meal were mixed in a mass ratio of 3:2:1.

[0012] This invention also provides a method for preparing a wheat zinc-selenium bio-organic foliar fertilizer, comprising the following preparation steps: The fermentation substrate was mixed with water and then inoculated with a compound bacterial agent for fermentation treatment to obtain the fermentation substrate mother liquor; After dissolving seaweed extract in water, zinc sulfate, citric acid, and compound amino acids were added, and the mixture underwent segmented chelation to obtain a chelated solution. Sodium selenite was dissolved in water by stirring, and then some of the fermentation substrate mother liquor was added for complexation treatment to obtain a complex solution. The chelating solution and complexing solution were mixed and then added to the remaining fermentation substrate mother liquor and potassium sorbate for further processing to obtain wheat zinc selenium bio-organic foliar fertilizer.

[0013] Furthermore, the compound microbial agent is composed of Bacillus subtilis, Saccharomyces cerevisiae, and Aspergillus niger in a mass ratio of 2:1:1.

[0014] Furthermore, the fermentation process specifically includes: Adjust the moisture content of the fermentation substrate to 60% by adding water, then inoculate the substrate with 3% by weight of a compound microbial agent. Incubate at 35℃ and 0.8-1.2m. 3 / (m 3 Under aeration conditions of h), aerobic fermentation was carried out for 10 days. After the fermentation was completed, the fermentation system was filtered at a pressure of 0.5 MPa. The filtrate was then filtered through a 5 μm filter membrane to obtain the fermentation substrate mother liquor.

[0015] Furthermore, the segmented chelation treatment specifically includes: Take 40% water by mass, heat it to 45℃, add seaweed extract and stir until dissolved. Then add zinc sulfate and stir at 400 r / min for 1.5 h. Then add citric acid to adjust the pH of the system to between 4.5 and 5.0, and continue stirring at 400 r / min for 15 min. Finally, add compound amino acids, heat to 55℃, and continue stirring at 400 r / min for 1.5 h to obtain the chelate solution.

[0016] Furthermore, the complexation process specifically includes: Add 20% by weight of water to sodium selenite and stir until dissolved. Add 1 / 3 volume of the fermentation substrate mother liquor, stir, and adjust the pH to between 6.0 and 6.5. Stir at 150 r / min at 30℃ for 30 min to obtain the complexing solution.

[0017] Furthermore, the allocation process specifically includes: After mixing the chelating and complexing solutions, add the remaining 2 / 3 of the fermentation substrate mother liquor and stir for 30 minutes. Adjust the pH of the system to 6.2-6.8 with sodium hydroxide, add potassium sorbate, and stir until dissolved. Add the remaining 40% by weight of water, stir to mix, and filter through a 2μm filter membrane. Collect the filtrate.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention uses a high amount of zinc sulfate as the zinc source, combined with a multi-component chelation system of alginic acid + amino acids + citric acid, which solves the problem that simply increasing the amount of zinc fertilizer can easily lead to precipitation and low absorption efficiency.

[0019] 2. This invention abandons the traditional physical mixing process and EDTA chelating agent, and constructs a zinc-selenium synergistic stable system through stepwise chelation and complexation: zinc ions first form multi-component chelates with alginic acid and amino acids, and selenium ions form complexes with humic acid and polypeptides in the fermentation substrate. The two systems form a stable complex system through hydrogen bonds and van der Waals forces during final formulation, avoiding direct competition between zinc and selenium ions for chelation sites, thereby improving the utilization rate of zinc and selenium.

[0020] 3. This invention combines zinc and selenium fortification with the biostimulatory effects of alginic acid extract, compound amino acids, and fermentation substrate: alginic acid extract can promote wheat root growth, improve leaf photosynthetic efficiency, and enhance wheat's drought and disease resistance; compound amino acids can be directly absorbed and utilized by wheat, supplementing protein synthesis raw materials and improving grain quality; organic matter and beneficial bacteria metabolites in the fermentation substrate can regulate wheat growth rhythm and promote nutrient transport, achieving a three-in-one effect of wheat fortification, stress resistance enhancement, and yield increase. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 : A graph showing the zinc content of wheat grains in each treatment group provided in the embodiments of the present invention; Figure 2 : A graph showing the selenium content of wheat grains in each treatment group provided in the embodiments of the present invention; Detailed Implementation

[0023] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0024] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0025] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0026] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0027] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0028] This invention provides a wheat zinc-selenium bio-organic foliar fertilizer, comprising the following components in parts by weight: The fermentation substrate consists of 300-400 parts, zinc sulfate 40-60 parts, sodium selenite 2-5 parts, alginate extract 15-25 parts, compound amino acids 80-120 parts, potassium sorbate 1-2 parts, and water 435-554 parts.

[0029] A wheat zinc-selenium bio-organic foliar fertilizer, wherein the preferred mass proportions of each component are: The mixture consists of 350 parts fermentation substrate, 50 parts zinc sulfate, 3 parts sodium selenite, 20 parts alginate extract, 100 parts compound amino acids, 1.5 parts potassium sorbate, and 500 parts water.

[0030] It is understandable that this invention uses a high amount of zinc sulfate as the zinc source, combined with a multi-component chelation system of alginic acid + amino acids + citric acid, which solves the problem that simply increasing the amount of zinc fertilizer can easily lead to precipitation and low absorption efficiency.

[0031] It is understandable that this invention combines zinc and selenium fortification with the biostimulatory effects of alginic acid extract, compound amino acids, and fermentation substrate: alginic acid extract can promote wheat root growth, improve leaf photosynthetic efficiency, and enhance wheat's drought and disease resistance; compound amino acids can be directly absorbed and utilized by wheat, supplementing protein synthesis raw materials and improving grain quality; organic matter and beneficial bacteria metabolites in the fermentation substrate can regulate wheat growth rhythm and promote nutrient transport, achieving a three-in-one effect of wheat fortification, stress resistance enhancement, and yield increase.

[0032] In this invention, the preparation method of the alginate extract is as follows: After rinsing the *Tetracentron sinense* three times with water, dry it at 60℃ for 8 hours. After drying, pulverize it to 20-40 mesh to obtain *Tetracentron sinense* powder. Add the *Alternaria buergeriana* powder to water at a ratio of 1g:20ml, stir, then add 1% (by weight) of the compound enzyme preparation to the water. Adjust the pH of the system to between 4.8 and 5.2, and then enzymatically hydrolyze the mixture at 55℃ with a stirring speed of 150r / min for 4.5h to obtain the enzymatic hydrolysate. The enzymatic hydrolysate was heated to 90°C and kept at that temperature for 15 minutes. After cooling, it was filtered under a pressure of 0.2 MPa. The filtrate was collected and filtered through a 1 μm filter membrane to obtain the crude extract. Add 2 times the volume of ethanol to the crude extract, stir and let stand for 24 hours. Then centrifuge at 4000 r / min for 15 min, collect the precipitate, wash the precipitate twice with ethanol, and then add the precipitate to water at a ratio of 1 g: 15 ml of precipitate to water and stir to dissolve. Then spray dry to obtain alginate extract. The compound enzyme preparation is formulated with cellulase and pectinase in a mass ratio of 3:1.

[0033] Specifically, the enzyme activities of cellulase and pectinase are both ≥5000 U / g.

[0034] Understandably, using high-quality *Alternaria latifolia* as raw material, and pre-treating it through temperature-controlled drying and graded pulverization, ensures both the purity of the raw material and improves the uniformity of subsequent reactions. The use of a composite enzymatic hydrolysis system with cellulase and pectinase in a 3:1 mass ratio can efficiently destroy the cell wall structure of brown algae while preserving key active groups such as carboxyl and hydroxyl groups to the greatest extent. Subsequently, enzyme inactivation and multi-stage filtration are used to remove residues and fine impurities. Purification is then achieved through ethanol precipitation and washing, combined with vacuum concentration and spray drying to obtain the solid powder product.

[0035] In this invention, the preparation method of the complex amino acid is as follows: Take soybean meal, grind it to a particle size of 40-60 mesh, and then sterilize it at 121℃ for 20 minutes to obtain sterilized soybean meal; Sterilized soybean meal was added to water at a ratio of 1g:1.5ml, stirred, and then inoculated with a compound fermentation agent containing 2.5% of sterilized soybean meal plasmid. The mixture was then incubated at 35℃ and 0.6ml. 3 / (m 3 Aerobic fermentation was carried out at an aeration rate of ·h for 72h. After the fermentation, 0.5% by weight of neutral protease of the fermentation product was added to adjust the pH of the system to between 6.5 and 7.0. Enzymatic hydrolysis was carried out at 50℃ and 200r / min for 2h. Then, the temperature was raised to 85℃ and held for 10min. After cooling to room temperature, the mixture was filtered at a pressure of 0.3MPa. 0.3% by weight of activated carbon was added to the filtrate and decolorized at 60℃ for 30min. The activated carbon was then removed by filtration. The filtrate was concentrated under reduced pressure at -0.09MPa and 65℃ for 3h to obtain the complex amino acids.

[0036] It is understandable that the pulverization and sterilization steps in the pretreatment stage of the preparation method of the compound amino acids can avoid contamination by miscellaneous bacteria, laying a pure foundation for subsequent reactions; inoculation with a mixed agent of Bacillus subtilis and Aspergillus niger can efficiently produce hydrolytic enzymes such as proteases, which can initially degrade the macromolecular proteins in soybean meal, and the metabolites formed during the fermentation process can enhance the activity of amino acids; the subsequent addition of neutral proteases for synergistic enzymatic hydrolysis can achieve deep degradation of proteins, ultimately obtaining a compound product containing a variety of free amino acids.

[0037] In this invention, the fermentation substrate is prepared as follows: Peanut cake powder, corn stalk powder, and soybean meal were mixed in a mass ratio of 3:2:1.

[0038] Understandably, peanut meal and soybean meal are rich in nitrogen sources such as protein and amino acids, which can provide sufficient nutrition for the growth of compound microbial agents (such as Bacillus subtilis). Corn stalk powder is rich in carbon sources such as cellulose, which can adjust the carbon-nitrogen ratio of the mixed raw materials to a suitable fermentation range (25-30:1), greatly improving the activity and fermentation efficiency of the microbial agents and promoting the full degradation of raw materials into active ingredients such as humic acid, polypeptides, and small molecule organic matter. The fermentation products can not only form stable selenium complexes with sodium selenite, but also work synergistically with the zinc-alginic acid-amino acid chelate system to enhance the stability and nutrient adhesion of foliar fertilizers. The organic matter and beneficial bacterial metabolites contained therein can also play a biostimulatory role, working synergistically with alginic acid extract and compound amino acids to improve wheat stress resistance and yield.

[0039] This invention also proposes a method for preparing a wheat zinc-selenium bio-organic foliar fertilizer, comprising the following preparation steps: The fermentation substrate was mixed with water and then inoculated with a compound bacterial agent for fermentation treatment to obtain the fermentation substrate mother liquor; After dissolving seaweed extract in water, zinc sulfate, citric acid, and compound amino acids were added, and the mixture underwent segmented chelation to obtain a chelated solution. Sodium selenite was dissolved in water by stirring, and then some of the fermentation substrate mother liquor was added for complexation treatment to obtain a complex solution. The chelating solution and complexing solution were mixed and then added to the remaining fermentation substrate mother liquor and potassium sorbate for further processing to obtain wheat zinc selenium bio-organic foliar fertilizer.

[0040] Understandably, this invention abandons the traditional physical mixing process and EDTA chelating agent, and constructs a zinc-selenium synergistic stable system through stepwise chelation and complexation: zinc ions first form multi-component chelates with alginic acid and amino acids, and selenium ions form complexes with humic acid and peptides in the fermentation substrate. The two systems form a stable composite system through hydrogen bonds and van der Waals forces during final formulation, avoiding direct competition between zinc and selenium ions for chelation sites, thereby improving the utilization rate of zinc and selenium.

[0041] In this invention, the compound microbial agent is composed of Bacillus subtilis, Saccharomyces cerevisiae and Aspergillus niger in a mass ratio of 2:1:1.

[0042] Specifically, the Bacillus subtilis, Saccharomyces cerevisiae, and Aspergillus niger are all commercially available strains commonly used in the field and obtained through purchase. Furthermore, the activity of each of the Bacillus subtilis, Saccharomyces cerevisiae, and Aspergillus niger is ≥1×10⁻⁶. 9 CFU / g.

[0043] Understandably, Bacillus subtilis can produce various hydrolytic enzymes such as proteases and cellulases, which can efficiently degrade the protein in peanut cake powder and soybean meal, as well as some of the cellulose in corn stalk powder. At the same time, its metabolites can inhibit the growth of harmful pathogens in the fermentation system, ensuring the stability of the fermentation process. Aspergillus niger is good at secreting highly active cellulase and pectinase, which can specifically decompose the cellulose in corn stalk powder and pectin in the raw materials, breaking down the structural barriers of the raw materials and promoting the release of nutrients. Saccharomyces cerevisiae can secrete growth factors such as amino acids and vitamins, providing nutritional support for the growth and reproduction of the other two strains. It can also work with them to transform macromolecules in the raw materials, ultimately efficiently degrading the mixed raw materials of peanut cake powder, corn stalk powder, and soybean meal into active ingredients such as humic acid, small molecule peptides, and amino acids, thereby increasing the organic matter content and biological activity of the fermentation substrate.

[0044] In this invention, the fermentation process specifically includes: Adjust the moisture content of the fermentation substrate to 60% by adding water, then inoculate the substrate with 3% by weight of a compound microbial agent. Incubate at 35℃ and 0.8-1.2m. 3 / (m 3 Under aeration conditions of h), aerobic fermentation was carried out for 10 days. After the fermentation was completed, the fermentation system was filtered at a pressure of 0.5 MPa. The filtrate was then filtered through a 5 μm filter membrane to obtain the fermentation substrate mother liquor.

[0045] Specifically, the mixture is turned over once a day during fermentation.

[0046] In this invention, the segmented chelation treatment specifically includes: Take 40% water by mass, heat it to 45℃, add seaweed extract and stir until dissolved. Then add zinc sulfate and stir at 400 r / min for 1.5 h. Then add citric acid to adjust the pH of the system to between 4.5 and 5.0, and continue stirring at 400 r / min for 15 min. Finally, add compound amino acids, heat to 55℃, and continue stirring at 400 r / min for 1.5 h to obtain the chelate solution.

[0047] Specifically, 40% by weight of water was added to a reaction vessel, and the temperature was raised to 45°C. Alginic acid extract was added and stirred until completely dissolved. Zinc sulfate was then slowly added while stirring at 400 rpm, and the reaction was carried out at a constant temperature for 1.5 hours, allowing the carboxyl and hydroxyl groups of alginic acid to preferentially bind with zinc ions, completing the initial chelation. Citric acid was then added to adjust the pH of the system to between 4.5 and 5.0, and the mixture was stirred at 400 rpm for 15 minutes. At this point, citric acid acted as an auxiliary chelating agent, forming a synergistic coordination structure with the incompletely bound zinc ions and alginic acid. Finally, a complex amino acid was added, and the temperature was raised to 55°C, and the reaction was continued for 1.5 hours. The amino and carboxyl groups of the amino acids were used to further construct a stable zinc-alginic acid-amino acid multi-component chelate structure, yielding the chelate solution.

[0048] Understandably, the process involves first fully dissolving the alginic acid extract to provide sufficient active sites for the chelation reaction. Then, zinc sulfate is added and the reaction is kept at a certain temperature, allowing the carboxyl and hydroxyl groups of the alginic acid to preferentially bind with zinc ions to complete the initial chelation. This avoids the problem of citric acid, due to its small molecular weight and rapid chelation kinetics, preferentially occupying zinc ion coordination sites. Adding citric acid then precisely adjusts the system pH to 4.5-5.0, the optimal pH range for zinc-alginic acid-amino acid chelation, and also acts as an auxiliary chelating agent to form a synergistic coordination structure with the incompletely bound zinc ions and alginic acid, further enhancing the stability of zinc ions. Finally, the complex amino acids are added and the temperature is raised to continue the reaction. The amino and carboxyl groups of the amino acids construct a stable zinc-alginic acid-amino acid multi-component chelate structure, which not only solves the bottleneck of easy precipitation when simply increasing the amount of zinc fertilizer, but also allows the complex amino acids and alginic acid to synergistically load zinc ions.

[0049] In this invention, the complexation process specifically includes: Add 20% by weight of water to sodium selenite and stir until dissolved. Add 1 / 3 volume of the fermentation substrate mother liquor, stir, and adjust the pH to between 6.0 and 6.5. Stir at 150 r / min at 30℃ for 30 min to obtain the complexing solution.

[0050] Understandably, sodium selenite is first dissolved in 20% water according to the formula, and then 1 / 3 of the fermentation substrate mother liquor is added. The abundant humic acid, polypeptides and other active ingredients in the substrate specifically bind to selenium ions, replacing traditional chemical chelating agents. This avoids competition for coordination sites between selenium ions and zinc chelating systems, and also forms a stable selenium complex. Adjusting the pH to 6.0-6.5 ensures that the complexation reaction proceeds fully, significantly improving the stability of selenium and reducing the risk of precipitation during subsequent compounding. The resulting selenium complex solution is highly compatible with the chelating solution. After mixing, a stable composite system is formed through intermolecular forces, and the complexed selenium is more easily absorbed and utilized by wheat.

[0051] In this invention, the blending process specifically includes: After mixing the chelating solution and the complexing solution, add the remaining 2 / 3 of the fermentation substrate mother liquor and stir for 30 minutes. Adjust the pH of the system to 6.2-6.8 with sodium hydroxide, add potassium sorbate, stir until dissolved, add the remaining 40% by weight of water, stir and mix, then filter through a 2μm filter membrane and collect the filtrate.

[0052] Understandably, the process involves first mixing the chelating solution and the selenium complexing solution to allow the two stable systems to fully integrate through hydrogen bonds and van der Waals forces, forming a zinc-selenium synergistic complex system and preventing stratification or precipitation. Adding the remaining fermentation substrate mother liquor further enhances system stability and replenishes organic matter and bioactive components, synergistically enhancing biostimulation efficacy with alginic acid extract and complex amino acids. The pH is precisely adjusted to 6.2-6.8 using sodium hydroxide (suitable for wheat leaf environment and ensuring the stability of the zinc-selenium complex / chelate), and potassium sorbate is added for preservation and to extend the shelf life of the finished product.

[0053] In this invention, the water is preferably deionized water, and the ethanol is preferably anhydrous ethanol.

[0054] Example 1 Raw materials: 300 parts fermentation substrate, 40 parts zinc sulfate, 2 parts sodium selenite, 15 parts alginate extract, 80 parts compound amino acids, 1 part potassium sorbate, and 435 parts water.

[0055] Raw material preparation: Fermentation substrate: Peanut cake powder, corn stalk powder and soybean meal are mixed in a mass ratio of 3:2:1.

[0056] Alginic acid extract: Add the algae powder to deionized water at a ratio of 1g:20ml, stir, then add 1% of the algae powder mass of compound enzyme preparation, adjust the pH of the system to between 4.8 and 5.2, and then enzymatically hydrolyze at 55℃ with a stirring speed of 150r / min for 4.5h to obtain the enzymatic hydrolysate; The enzymatic hydrolysate was heated to 90°C and kept at that temperature for 15 minutes. After cooling, it was filtered under a pressure of 0.2 MPa. The filtrate was collected and filtered through a 1 μm filter membrane to obtain the crude extract. Add two volumes of anhydrous ethanol to the crude extract, stir, and let stand for 24 hours. Then, centrifuge at 4000 r / min for 15 min, collect the precipitate, wash the precipitate twice with anhydrous ethanol, and then add the precipitate to water at a ratio of 1 g: 15 ml of precipitate to deionized water and stir to dissolve. Then, spray dry to obtain the alginic acid extract. The compound enzyme preparation is prepared by a mass ratio of cellulase: pectinase = 3:1.

[0057] Compound amino acids: Take soybean meal, grind it to a particle size of 40-60 mesh, and then sterilize it at 121℃ for 20 minutes to obtain sterilized soybean meal; Sterilized soybean meal was added to deionized water at a ratio of 1g:1.5ml, stirred, and then inoculated with 2.5% of a compound fermentation agent containing sterilized soybean meal plasmid. The mixture was then incubated at 35℃ and 0.6ml. 3 / (m 3 Aerobic fermentation was carried out at an aeration rate of ·h for 72h. After the fermentation, 0.5% by weight of neutral protease of the fermentation product was added to adjust the pH of the system to between 6.5 and 7.0. Enzymatic hydrolysis was carried out at 50℃ and 200r / min for 2h. Then, the temperature was raised to 85℃ and held for 10min. After cooling to room temperature, the mixture was filtered at a pressure of 0.3MPa. 0.3% by weight of activated carbon was added to the filtrate and decolorized at 60℃ for 30min. The activated carbon was then removed by filtration. The filtrate was concentrated under reduced pressure at -0.09MPa and 65℃ for 3h to obtain the complex amino acids.

[0058] The compound microbial agent is composed of Bacillus subtilis, Saccharomyces cerevisiae, and Aspergillus niger in a mass ratio of 2:1:1. Preparation method: S1, 300. Add deionized water to the fermentation substrate to adjust the moisture content to 60%. Then inoculate the fermentation substrate with 3% by weight of compound microbial agent and incubate at 35℃ and 0.8-1.2m. 3 / (m 3 Under aeration conditions of h), aerobic fermentation was carried out for 10 days. After the fermentation was completed, the fermentation system was filtered at a pressure of 0.5 MPa. The filtrate was then filtered through a 5 μm filter membrane to obtain the fermentation substrate mother liquor. S2. Add 174 parts of deionized water to the reaction vessel, heat to 45°C, add alginate extract and stir until dissolved, then add 40 parts of zinc sulfate and stir at 400 r / min for 1.5 h. Then add citric acid to adjust the pH of the system to between 4.5 and 5.0, and continue stirring at 400 r / min for 15 min. Finally, add the complex amino acid, heat to 55°C, and continue stirring at 400 r / min for 1.5 h to obtain the chelate solution. S3. Take 87 parts of deionized water and add 2 parts of sodium selenite. Stir until dissolved, add 1 / 3 volume of the fermentation substrate mother liquor, stir and adjust the pH to between 6.0 and 6.5. Stir at 30°C at a constant temperature of 150 r / min for 30 min to obtain the complex solution. S4. After mixing the chelating solution and the complexing solution, add the remaining 2 / 3 of the fermentation substrate mother liquor and stir for 30 minutes. Adjust the pH of the system to 6.2-6.8 with sodium hydroxide, add 1 part of potassium sorbate, stir until dissolved, add the remaining 174 parts of deionized water, stir and mix, then filter through a 2μm filter membrane, and take the filtrate to obtain wheat zinc selenium bio-organic foliar fertilizer.

[0059] Example 2 The only difference from Example 1 is that the mass fractions of the raw material components are: 350 parts fermentation substrate, 50 parts zinc sulfate, 3 parts sodium selenite, 20 parts alginate extract, 100 parts compound amino acids, 1.5 parts potassium sorbate, and 500 parts water.

[0060] Example 3 The only difference from Example 1 is that the mass fractions of the raw material components are 400 parts of fermentation substrate, 60 parts of zinc sulfate, 5 parts of sodium selenite, 25 parts of alginic acid extract, 120 parts of compound amino acids, 2 parts of potassium sorbate, and 554 parts of water.

[0061] Application examples Liquid foliar fertilizer application method Preparation before application Dilution ratio: 1:100; Note: Formulas containing alginic acid have high viscosity and need to be stirred thoroughly until no sediment remains.

[0062] Selection of spraying equipment Choose an electric sprayer with good atomization effect (droplet diameter 50-100μm) to ensure uniform coverage of the leaf surface; avoid using coarse mist nozzles to reduce droplet roll-off loss.

[0063] II. Spraying Time and Frequency Optimal spraying time: early morning (after the dew has dried) or late afternoon (after 4:00 PM) on a sunny day, to avoid strong sunlight causing rapid evaporation from the leaves; if it rains within 6 hours after spraying, re-spray.

[0064] Key growth stage spraying plan: Jointing stage: spray once to enhance lodging resistance; Heading stage to grain filling stage: spray twice, with an interval of 7 days, which can significantly increase the zinc and selenium content of grains.

[0065] III. Key Points of Spraying Operation Spraying areas: Focus on spraying the back of the leaves (where the stomata are denser and the absorption efficiency is more than 30% higher than that of the front). Spray evenly at a 45° angle onto the upper and middle functional leaves of wheat (flag leaf and second leaf from the top).

[0066] Spraying amount control: per acre: 50L of diluted solution, enough to moisten the leaves but not drip; excessive spraying can easily cause leaf burn or nutrient waste.

[0067] Test case 1. Experimental Materials and Methods 1.1 Test Materials Test location: Zhanggufeng Village, Heliu Town, Yangxin County, Binzhou City, Shandong Province. Test period: October 15, 2021 - June 15, 2022.

[0068] Experimental crop: Wheat, Jimai 44.

[0069] Test soil: Brown soil, basic physicochemical properties: organic matter 14.4 g·kg -1 Alkaline nitrogen uptake: 76.1 mg·kg -1 Available phosphorus 8.8 mg·kg -1 182.0 mg / kg of readily available potassium -1 pH value 8.4.

[0070] 1.2 Experimental Design The experiment included four treatments: (1) Control T1: no foliar fertilizer was applied; (2) T2: the foliar fertilizer of the present invention was applied once (at the jointing stage): the wheat zinc-selenium bio-organic foliar fertilizer prepared in Example 2; (3) T3: the wheat zinc-selenium bio-organic foliar fertilizer prepared in Example 2 was applied twice (once at the jointing stage and once at the grain-filling stage); (4) T4: the wheat zinc-selenium bio-organic foliar fertilizer prepared in Example 2 was applied three times (once at the jointing stage and twice at the grain-filling stage, with an interval of 7 days). Each treatment was replicated four times. The amounts of nitrogen, phosphorus, and potassium fertilizers were the same for all treatments, with N, P2O5, and K2O applied per mu being 17 kg, 9.2 kg, and 5 kg, respectively. Among them, 40 kg / mu of compound fertilizer (20-23-5) and 3 kg / mu of potassium sulfate were applied as basal fertilizer. 30 kg / mu of high-nitrogen fertilizer (30-0-5) was applied as top dressing at the jointing stage. For treatments 2, 3, and 4, the dilution concentration was 1:100 each time, and the spraying rate was 50L / acre.

[0071] After harvest, wheat yield, zinc content, and selenium content in wheat grains were calculated for different treatment groups.

[0072] Wheat yields in different treatment groups are shown in Table 1: Table 1 Wheat yield under different treatments

[0073] As can be seen, compared with the control and water spraying treatment, spraying the foliar fertilizer of the present invention significantly increased wheat yield, by 5.2% and 3.4% respectively (Table 1). In the composition of wheat yield, compared with the control treatment, spraying the foliar fertilizer of the present invention significantly increased the thousand-grain weight of wheat, while the number of spikes and the number of grains per spike were not affected by the foliar fertilizer spraying.

[0074] The zinc and selenium content of wheat grains, as follows Figure 1-2 As shown, spraying the foliar fertilizer of this invention increased the zinc and selenium content of grains compared to the control treatment. The zinc content of grains after one, two, and three applications was 34.3, 41.4, and 46.2 mg / kg, respectively, representing increases of 43.4%, 73.0%, and 92.9% compared to the control treatment, with significant differences among the treatments. The selenium content of grains after one, two, and three applications was 76.3, 88.3, ​​and 11.4 ug / kg, respectively, representing increases of 68.4%, 94.7%, and 150.0% compared to the control treatment. The selenium content of wheat grains after one and two applications of the foliar fertilizer was significantly lower than that after three applications, but there was no significant difference between the one and two applications.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A wheat zinc-selenium bio-organic foliar fertilizer, characterized in that, The components include the following parts by mass: The fermentation substrate consists of 300-400 parts, zinc sulfate 40-60 parts, sodium selenite 2-5 parts, alginate extract 15-25 parts, compound amino acids 80-120 parts, potassium sorbate 1-2 parts, and water 435-554 parts.

2. The wheat zinc-selenium bio-organic foliar fertilizer according to claim 1, characterized in that, The preparation method of the alginate extract is as follows: After rinsing the *Tetracentron sinense* three times with water, dry it at 60℃ for 8 hours. After drying, pulverize it to 20-40 mesh to obtain *Tetracentron sinense* powder. Add the *Alternaria buergeriana* powder to water at a ratio of 1g:20ml, stir, then add 1% (by weight) of the compound enzyme preparation to the water. Adjust the pH of the system to between 4.8 and 5.2, and then enzymatically hydrolyze the mixture at 55℃ with a stirring speed of 150r / min for 4.5h to obtain the enzymatic hydrolysate. The enzymatic hydrolysate was heated to 90°C and kept at that temperature for 15 minutes. After cooling, it was filtered under a pressure of 0.2 MPa. The filtrate was collected and filtered through a 1 μm filter membrane to obtain the crude extract. Add 2 times the volume of ethanol to the crude extract, stir and let stand for 24 hours. Then centrifuge at 4000 r / min for 15 min, collect the precipitate, wash the precipitate twice with ethanol, and then add the precipitate to water at a ratio of 1 g: 15 ml of precipitate to water and stir to dissolve. Then spray dry to obtain alginate extract. The compound enzyme preparation is formulated with cellulase and pectinase in a mass ratio of 3:

1.

3. The wheat zinc-selenium bio-organic foliar fertilizer according to claim 2, characterized in that, The preparation method of the complex amino acid is as follows: Take soybean meal, grind it to a particle size of 40-60 mesh, and then sterilize it at 121℃ for 20 minutes to obtain sterilized soybean meal; Sterilized soybean meal was added to water at a ratio of 1g:1.5ml, stirred, and then inoculated with a compound fermentation agent containing 2.5% of sterilized soybean meal plasmid. The mixture was then incubated at 35℃ and 0.6ml. 3 / (m 3 Aerobic fermentation was carried out at an aeration rate of ·h for 72h. After the fermentation, 0.5% by weight of neutral protease of the fermentation product was added to adjust the pH of the system to between 6.5 and 7.

0. Enzymatic hydrolysis was carried out at 50℃ and 200r / min for 2h. Then, the temperature was raised to 85℃ and held for 10min. After cooling to room temperature, the mixture was filtered at a pressure of 0.3MPa. 0.3% by weight of activated carbon was added to the filtrate and decolorized at 60℃ for 30min. The activated carbon was then removed by filtration. The filtrate was concentrated under reduced pressure at -0.09MPa and 65℃ for 3h to obtain the complex amino acids.

4. The wheat zinc-selenium bio-organic foliar fertilizer according to claim 3, characterized in that, The preparation method of the fermentation substrate is as follows: Peanut cake powder, corn stalk powder, and soybean meal were mixed in a mass ratio of 3:2:

1.

5. A method for preparing a wheat zinc-selenium bio-organic foliar fertilizer as described in any one of claims 1-4, characterized in that, The preparation steps include the following: The fermentation substrate was mixed with water and then inoculated with a compound bacterial agent for fermentation treatment to obtain the fermentation substrate mother liquor; After dissolving seaweed extract in water, zinc sulfate, citric acid, and compound amino acids were added, and the mixture underwent segmented chelation to obtain a chelated solution. Sodium selenite was dissolved in water by stirring, and then some of the fermentation substrate mother liquor was added for complexation treatment to obtain a complex solution. The chelating solution and complexing solution were mixed and then added to the remaining fermentation substrate mother liquor and potassium sorbate for further processing to obtain wheat zinc selenium bio-organic foliar fertilizer.

6. The method for preparing wheat zinc-selenium bio-organic foliar fertilizer according to claim 5, characterized in that, The compound microbial agent is composed of Bacillus subtilis, Saccharomyces cerevisiae and Aspergillus niger in a mass ratio of 2:1:

1.

7. The method for preparing wheat zinc-selenium bio-organic foliar fertilizer according to claim 6, characterized in that, The fermentation process specifically involves: Adjust the moisture content of the fermentation substrate to 60% by adding water, then inoculate the substrate with 3% by weight of a compound microbial agent. Incubate at 35℃ and 0.8-1.2m. 3 / (m 3 Under aeration conditions of h), aerobic fermentation was carried out for 10 days. After the fermentation was completed, the fermentation system was filtered at a pressure of 0.5 MPa. The filtrate was then filtered through a 5 μm filter membrane to obtain the fermentation substrate mother liquor.

8. The method for preparing wheat zinc-selenium bio-organic foliar fertilizer according to claim 7, characterized in that, The segmented chelation treatment specifically involves: Take 40% water by mass, heat it to 45℃, add seaweed extract and stir until dissolved. Then add zinc sulfate and stir at 400 r / min for 1.5 h. Then add citric acid to adjust the pH of the system to between 4.5 and 5.0, and continue stirring at 400 r / min for 15 min. Finally, add compound amino acids, heat to 55℃, and continue stirring at 400 r / min for 1.5 h to obtain the chelate solution.

9. The method for preparing wheat zinc-selenium bio-organic foliar fertilizer according to claim 8, characterized in that, The complexation process specifically involves: Add 20% by weight of water to sodium selenite and stir until dissolved. Add 1 / 3 volume of the fermentation substrate mother liquor, stir, and adjust the pH to between 6.0 and 6.

5. Stir at 150 r / min at 30℃ for 30 min to obtain the complexing solution.

10. The method for preparing wheat zinc-selenium bio-organic foliar fertilizer according to claim 9, characterized in that, The specific process of blending is as follows: After mixing the chelating solution and the complexing solution, add the remaining 2 / 3 of the fermentation substrate mother liquor and stir for 30 minutes. Adjust the pH of the system to 6.2-6.8 with sodium hydroxide, add potassium sorbate, stir until dissolved, add the remaining 40% by weight of water, stir and mix, then filter through a 2μm filter membrane and collect the filtrate.

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