A bio-based sugar alcohol chelated liquid slow-release microelement fertilizer, a preparation method and application thereof

Abstract

This invention discloses a bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer, its preparation method, and its application, relating to the field of fertilizer technology. The invention uses bio-based sugar alcohol, biopolysaccharide, inorganic micronutrient fertilizer, eutectic solvent, and functional additives as raw materials to prepare the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer. A dual green chelation system is constructed using bio-based sugar alcohol and biopolysaccharide, and then the eutectic solvent is synergistically applied to the dual chelation system to build a slow-release polymer network. This solves the problems of low solubility and easy crystallization in traditional inorganic salt micronutrient fertilizers. Simultaneously, by reducing the solute crystallization energy and utilizing steric hindrance, it effectively prevents antagonistic precipitation between different ions, allowing the product to remain homogeneous, stable, and free from precipitation during long-term storage. Furthermore, the synergistic effect of biopolysaccharide, bio-based sugar alcohol, and eutectic solvent can improve the nutrient absorption capacity of plants.

Description

Technical Field

[0001] This invention relates to the field of fertilizer technology, and in particular to a bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer, its preparation method, and its application. Background Technology

[0002] Micronutrients, essential nutrients for crop growth and development, play an irreplaceable role in key physiological processes such as regulating enzymatic reactions, participating in photosynthesis, promoting nutrient metabolism, and enhancing stress resistance. Their sufficiency and effectiveness directly impact crop yield and quality. Micronutrient fertilizers come in both solid and liquid forms. Liquid micronutrient fertilizers are clean and environmentally friendly in their production process, exhibiting high nutrient uniformity. In field application, nutrients dissolve fully and can be precisely supplied through foliar spraying or drip irrigation. Their liquid form is easily absorbed by crops, quickly replenishing nutrient deficiencies. The liquid form is less likely to burn crop roots and seedlings, and its distribution in the soil is more even, avoiding the damage caused by excessively high local concentrations of solid fertilizers. Furthermore, they are highly compatible with modern intensive agricultural fertilization systems and can be mixed with acidic pesticides, herbicides, and plant growth regulators to achieve multiple benefits in a single application, significantly improving operational efficiency, saving labor, increasing fertilization efficiency, and reducing fertilizer waste.

[0003] However, existing micronutrient liquid fertilizers still have the following problems in production: some micronutrient inorganic fertilizers have limited solubility in water, such as borax decahydrate, copper sulfate pentahydrate, and ferrous sulfate heptahydrate, whose solubility at room temperature is usually less than 30g / 100g water, resulting in limited product concentration and high storage and transportation costs; poor system stability, with large differences in the amount and chemical properties of different components, leading to poor compatibility and mixing uniformity; ion antagonism in the compounding of multiple micronutrients, which easily leads to precipitation; and crystallization, stratification, and precipitation of different components in the product during storage due to temperature and pH changes, which not only causes crystal precipitation and clogging of fertilizer application equipment, but also limits crop absorption and utilization; in addition, existing products have single formulations and functions, only serving as nutrient supply, lacking stress resistance functions such as cold resistance, drought resistance, and high temperature resistance, and have poor compatibility with macronutrient fertilizers and other agrochemical products, making it difficult to adapt to the needs of complex agricultural production scenarios. Currently, common technologies often employ chemically synthesized chelating agents and surfactants to improve the stability and compatibility of liquid fertilizers. However, these additives are costly, pose significant environmental risks, are difficult to biodegrade, and tend to remain in the environment for extended periods, activating heavy metals in the soil and creating potential ecological threats. Therefore, there is an urgent need to develop a green and environmentally friendly liquid slow-release micronutrient fertilizer with high solubility, high stability, high compatibility, and a multifunctional additive system.

[0004] In the prior art, CN120817830 A discloses a boron-zinc-molybdenum synergistic compound fertilizer, including sodium tetraborate tetrahydrate, sugar alcohol chelated zinc, sodium molybdate, activator, and sugar alcohol chelated zinc, which utilizes the synergistic effect of three elements, B, Zn, and Mg, to reduce the problem of insufficient or excessive amounts of a single element. However, the solid compound fertilizer is prepared through high-speed shear emulsification, granulation, coating, drying, and sieving processes, which are complex and difficult to control. The use of PBS-degraded polymer coating results in high production costs. This fertilizer is suitable for soil basal application but not for fertigation or foliar spraying. CN116813389 A discloses a full-element biochemical chelated liquid water-soluble fertilizer, including macro-elements, meso-elements, special elements, functional elements, chelating agents (EDTA), wetting agents, and synergistic element wetting agents mixed together to achieve the mutual solubility of 17 nutrient elements. However, this patent mixes phosphorus with trace elements, which easily forms insoluble phosphate precipitates, resulting in poor solution stability and homogeneity. Furthermore, the use of EDTA as a chelating agent poses an environmental residue risk. In addition, this patent lacks foliar adhesion, rain erosion resistance, and intrinsic stress resistance functions, limiting its application effectiveness. CN112592234A discloses a method using a compound sugar alcohol as a chelating liquid, combined with a mixture of trace elements and glycerol, to prepare a compound sugar alcohol chelated trace element chelate. This technology shows good chelating ability for calcium and boron, but its stability is easily compromised when mixed with foliar fertilizers containing magnesium, zinc, iron, and other metal elements. It lacks antioxidant properties, especially for easily oxidized metal elements such as iron and manganese, and its fertilizer efficacy is easily affected by valence state changes. Moreover, this invention has a single composition and poor compatibility with other agricultural products.

[0005] Therefore, selecting a suitable chelating agent to prepare a liquid fertilizer containing micronutrients can not only solve the problems of low solubility and easy crystallization of traditional inorganic salt micronutrient fertilizers, but also improve stability and make it suitable for multiple application scenarios, including foliar spraying. This has become an urgent need to achieve precise and efficient nutrient management. Summary of the Invention

[0006] In view of the above-mentioned prior art, the purpose of this invention is to provide a bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer, its preparation method and application.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer, which is prepared by mixing biopolysaccharide, bio-based sugar alcohol, eutectic solvent, functional additives, and inorganic micronutrient fertilizer in a mass ratio of (0.1-20):(1-182):(0.5-25):(0.01-5):(1-220). The biopolysaccharide is one or more of chitosan, fucoidan, chitosan oligosaccharide, trehalose, and chitin oligosaccharide, and the bio-based sugar alcohol is one or more of xylitol, sorbitol, mannitol, maltitol, and euonymus alcohol.

[0008] Preferably, the eutectic solvent is prepared by mixing hydrogen bond acceptors and hydrogen bond donors in a mass ratio of 1:(0.01-25).

[0009] Furthermore, the hydrogen bond acceptor is selected from choline chloride, betaine hydrochloride, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, benzyltriethylammonium chloride, triethylamine hydrochloride, dialcyldimethylammonium chloride, tetradecyldimethylbenzylammonium chloride, and dodecyldimethylbenzylammonium chloride; the hydrogen bond donor is selected from at least one of betaine, proline, glutamic acid, alanine, glycine, serine, polyglutamic acid, urea, oxalic acid, lactic acid, gallic acid, vitamin C, tannic acid, melatonin, hydroquinone, and glycerol.

[0010] Preferably, the functional additive is prepared by mixing pH adjuster, dispersant and anti-erosion agent in a mass ratio of (0.1-16):(0.1-54):(0.5-22).

[0011] Furthermore, the pH adjuster is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, citric acid, oxalic acid, acetic acid, malic acid, sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate; the dispersant is one or more of alkyl polysaccharide glycoside, fatty alcohol polyoxyethylene ether, Tween, sodium dodecylbenzenesulfonate, ethoxy-modified trisiloxane, triethanolamine, and polyoxyethylene fatty acid ester; and the anti-erosion agent is one or more of polyether-modified trisiloxane, polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, starch, xanthan gum, and sodium carboxymethyl cellulose.

[0012] Preferably, the inorganic micronutrient fertilizer is one or more of the following: boron fertilizer, zinc fertilizer, iron fertilizer, copper fertilizer, molybdenum fertilizer, manganese fertilizer, selenium fertilizer, magnesium fertilizer, and calcium fertilizer.

[0013] Furthermore, the boron fertilizer is one or more of boric acid, borax, and disodium octaborate tetrahydrate; the zinc fertilizer is one or more of zinc sulfate monohydrate, zinc sulfate, zinc chloride, zinc oxide, zinc sulfide, and zinc phosphate; the iron fertilizer is one or more of ferric sulfate, ferrous sulfate, ferric oxide, ferrous phosphate monohydrate, ferrous ammonium sulfate, and ferrous carbonate; the copper fertilizer is one or more of copper sulfate, basic copper sulfate, copper chloride, copper oxide, cuprous oxide, and copper-containing slag; the molybdenum fertilizer is one or more of ammonium molybdate, sodium molybdate, and molybdenum trioxide; the manganese fertilizer is one or more of manganese sulfate, manganese carbonate, manganese chloride, and manganese oxide; the selenium fertilizer is sodium selenate and / or sodium selenite; the magnesium fertilizer is one or more of magnesium sulfate, magnesium chloride, and magnesium nitrate; and the calcium fertilizer is calcium chloride and / or calcium nitrate.

[0014] A second aspect of the present invention provides a method for preparing the above-mentioned bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer, comprising the following steps: Biopolysaccharide, bio-based sugar alcohol, inorganic micronutrient fertilizer, functional additives, eutectic solvent and water are mixed and stirred evenly, then heated to react, and the reaction product is collected, which is the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer.

[0015] Preferably, the mass ratio of biopolysaccharide to water is (0.1-20):50.

[0016] Preferably, the stirring speed is 300-800 rpm.

[0017] Preferably, the heating temperature is 40-80℃ and the reaction time is 15-60min.

[0018] A third aspect of the present invention provides the application of the above-mentioned bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer in agricultural planting.

[0019] As a preferred embodiment, the application method includes at least one of the following (1)-(4): (1) Spraying after dilution: Dilute the above-mentioned bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer with water to obtain a diluted solution, and spray the diluted solution on the leaves or stems of the crop. (2) Apply after making into granules: Add the above-mentioned bio-based sugar alcohol chelated liquid slow-release trace element fertilizer to the base fertilizer, mix and granulate to make granules before application; (3) Application after preparation as controlled-release fertilizer: Apply the above-mentioned bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer to the inner matrix or the outer controlled-release membrane to form controlled-release fertilizer before application. (4) Drip irrigation mixed application: After mixing the above-mentioned bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer and liquid fertilizer, add it to the drip irrigation system for drip irrigation application.

[0020] Furthermore, in application method (1), the dilution ratio is 50-1000 times, the spraying time is from the seedling stage of the crop to before harvest or when the crop shows nutrient deficiency symptoms; the spraying frequency is once every 7-15 days, for a total of 2 sprays; the amount sprayed each time is 50-150L / mu.

[0021] Furthermore, in application method (2), the base fertilizer includes one or more of urea, compound fertilizer, potassium fertilizer or phosphate fertilizer; the amount of micronutrient fertilizer added in bio-based sugar alcohol chelated liquid slow release is 0.5%-5% of the mass of the base fertilizer.

[0022] Furthermore, in application method (3), the spraying temperature is 40-70℃; the amount of inner matrix sprayed is 1%-3% of the mass of controlled-release fertilizer; and the amount of outer controlled-release membrane sprayed is 0.5%-2% of the total mass of controlled-release fertilizer.

[0023] Furthermore, in application method (4), the mass ratio of bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer to liquid fertilizer is 1:(10-50).

[0024] The beneficial effects of this invention are: 1. This invention uses bio-based sugar alcohols, biopolysaccharides, inorganic micronutrient fertilizers, eutectic solvents, and functional additives as raw materials to prepare a bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer. A dual green chelation system is constructed using bio-based sugar alcohols and biopolysaccharides. Then, the eutectic solvent is synergistically applied to the dual chelation system to construct a slow-release polymer network. This not only forms easily water-soluble and stable complexes with micronutrient ions, solving the problems of low solubility and easy crystallization in traditional inorganic salt micronutrient fertilizers, but also effectively prevents antagonistic precipitation between different ions by reducing the solute crystallization energy and increasing steric hindrance. The product can be stored for a long time while maintaining homogeneity, stability, and no precipitation. Furthermore, the synergistic effect of biopolysaccharides and bio-based sugar alcohols can form a mild slow-release protective layer on leaves or in the soil, controlling the nutrient release rate and prolonging the fertilizer effect. As an efficient carrier, it facilitates the foliar absorption of micronutrients and solves the problems of easy leaching and fixation of micronutrients.

[0025] 2. The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer prepared by this invention exhibits good and stable compatibility with formulations of different properties, such as solid fertilizers, liquid fertilizers, and pesticides, and has flexible and wide-ranging applications. Traditional micronutrient fertilizers (such as zinc, iron, copper, manganese, calcium, and magnesium) are easily fixed when compounded with macronutrient phosphate fertilizers, making them difficult to integrate with traditional processes. By developing a compound liquid fertilizer system, easily fixed metal ions can be stabilized, improving the compatibility of different elements. Therefore, this invention can not only be used directly for foliar spraying after dilution, but also applied to traditional fertilizer granulation, granule coating, and controlled-release fertilizer manufacturing processes, achieving nutrient fortification and functional upgrades for bulk fertilizers. The use of anti-erosion agents and highly efficient wetting agents significantly reduces the surface tension of the liquid, allowing it to spread rapidly on crop leaves, forming a uniform and firm liquid film. This greatly improves adhesion and resistance to rain erosion, ensuring efficient deposition and uniform distribution of nutrients at the target site, overcoming the problems of easy rolling and uneven distribution in traditional liquid fertilizers.

[0026] 3. The core raw materials of this invention are all derived from renewable biomass. The preparation process is mild and low-energy. All components have good biodegradability, avoiding the potential environmental residues and ecological risks brought about by traditional EDTA chelating agents. By scientifically combining stress-resistant synergists and functional biopolysaccharides, crop growth regulation and efficient nutrient transport are achieved, constructing multiple stimulation functions. It can act as a signaling substance to induce crops to produce systemic resistance and enhance their resistance to abiotic stresses such as drought, low temperature, and salinity, as well as certain diseases. Attached Figure Description

[0027] Figure 1 : The slow-release performance of the liquid slow-release micronutrient fertilizers prepared in Example 1 and Comparative Examples 1-3 in water. Detailed Implementation

[0028] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, 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 application pertains.

[0029] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0030] The experimental materials used in the embodiments of this invention are all conventional experimental materials in the art and can be purchased through commercial channels.

[0031] Example 1: 1. Composition: The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer of this embodiment is made by mixing biopolysaccharide, bio-based sugar alcohol, eutectic solvent, functional additives, and inorganic micronutrient fertilizer in a mass ratio of 0.3:18:4:5:60. Among them, the biopolysaccharide is composed of chitosan oligosaccharide and chitosan in a mass ratio of 1:2, the bio-based sugar alcohol is sorbitol, the eutectic solvent is composed of choline chloride, glycerol and betaine in a mass ratio of 1:0.9:3, the functional additives are composed of citric acid, alkyl polysaccharide glycoside and sodium carboxymethyl cellulose in a mass ratio of 2:12:3, and the inorganic micronutrient fertilizer is made by mixing borax, magnesium chloride and manganese sulfate in a mass ratio of 7:1:2.

[0032] 2. Preparation method: Biopolysaccharide, bio-based sugar alcohol, eutectic solvent, functional additives, inorganic micronutrient fertilizer and water are mixed, with the mass ratio of biopolysaccharide to water being 0.3:50. The mixture is stirred at 600 rpm until homogeneous, heated to 80°C and reacted for 40 min. The reaction product is collected, which is the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer.

[0033] The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer prepared in this embodiment can be completely dissolved, and no insoluble precipitate is formed after standing for 2 hours.

[0034] Example 2: 1. Composition: The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer of this embodiment is made by mixing biopolysaccharide, bio-based sugar alcohol, eutectic solvent, functional additives, and inorganic micronutrient fertilizer in a mass ratio of 3:16:2:0.5:68. Among them, the bio-polysaccharide is trehalose, the bio-based sugar alcohol is mannitol, the eutectic solvent is composed of choline chloride, proline, and tannic acid in a mass ratio of 1:0.8:0.6, the functional additives are composed of potassium hydroxide, Tween, and sodium carboxymethyl cellulose in a mass ratio of 1:4:6, and the inorganic micronutrient fertilizer is made by mixing boric acid, magnesium chloride, zinc sulfate, ferrous sulfate, and ammonium molybdate in a mass ratio of 37:15:15:10:6.

[0035] 2. Preparation method: Biopolysaccharide, bio-based sugar alcohol, eutectic solvent, functional additives, inorganic micronutrient fertilizer and water are mixed, with the mass ratio of biopolysaccharide to water being 3:50. The mixture is stirred evenly at 500 rpm and heated to 60°C for 25 min. The reaction product is collected, which is the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer.

[0036] The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer prepared in this embodiment can be completely dissolved, and no insoluble precipitate is formed after standing for 2 hours.

[0037] Example 3: 1. Composition: The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer of this embodiment is made by mixing biopolysaccharide, bio-based sugar alcohol, eutectic solvent, functional additives, and inorganic micronutrient fertilizer in a mass ratio of 20:182:25:5:120. Among them, the biopolysaccharide is composed of chitosan oligosaccharide and fucoidan oligosaccharide in a 1:2 ratio; the bio-based sugar alcohol is made from maltitol and mannitol in a 1:1 mass ratio; the eutectic solvent is made from sodium dihydrogen phosphate, choline chloride, gallic acid, and urea in a mass ratio of 0.4:0.6:0.8:0.6; the inorganic micronutrient fertilizer is made from disodium octaborate tetrahydrate, magnesium chloride, zinc sulfate, ferrous sulfate, copper sulfate, ammonium molybdate, manganese sulfate, and sodium selenite in a mass ratio of 15:60:15:10:3:2:8:1; and the functional additive is made from citric acid, sodium dodecylbenzenesulfonate, and polyvinyl alcohol in a mass ratio of 6:1:3.

[0038] 2. Preparation method: Biopolysaccharide, bio-based sugar alcohol, eutectic solvent, functional additives, inorganic micronutrient fertilizer and water are mixed, with the mass ratio of biopolysaccharide to water being 20:50. The mixture is stirred evenly at 800 rpm and heated to 80°C for 60 min. The reaction product is collected, which is the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer.

[0039] The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer prepared in this embodiment can be completely dissolved, and no insoluble precipitate is formed after standing for 2 hours.

[0040] Example 4: 1. Composition: The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer of this embodiment is made by mixing biopolysaccharide, bio-based sugar alcohol, eutectic solvent, functional additives, and inorganic micronutrient fertilizer in a mass ratio of 10:92:20:3.5:40. Among them, the bio-polysaccharide is chitosan oligosaccharide, the bio-based sugar alcohol is xylitol, the eutectic solvent is composed of choline chloride and glycerol in a mass ratio of 1:2.8, the functional additives are composed of oxalic acid, triethanolamine and xanthan gum in a mass ratio of 4:2:1, and the inorganic micronutrient fertilizer is made by mixing disodium octaborate tetrahydrate, magnesium sulfate, zinc sulfate, ferrous ammonium sulfate, manganese sulfate and sodium molybdate in a mass ratio of 20:25:20:15:15:5.

[0041] 2. Preparation method: Biopolysaccharide, bio-based sugar alcohol, eutectic solvent, functional additives, inorganic micronutrient fertilizer and water are mixed, with the mass ratio of biopolysaccharide to water being 10:50. The mixture is stirred evenly at 800 rpm and heated to 80°C for 60 min. The reaction product is collected, which is the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer.

[0042] The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer prepared in this embodiment can be completely dissolved, and no insoluble precipitate is formed after standing for 2 hours.

[0043] Comparative Example 1: The difference between this comparative example and Example 1 is that biopolysaccharides (chitosan oligosaccharides + chitosan), bio-based sugar alcohols (sorbitol), and eutectic solvents (choline chloride, glycerol, and betaine) were not used in the preparation of the liquid slow-release micronutrient fertilizer. The specific preparation method is as follows: Inorganic micronutrient fertilizer, functional additives, and water were mixed in a mass ratio of 5:60:50, stirred at 600 rpm until homogeneous, heated to 80°C, and kept at that temperature for 40 minutes to obtain a common liquid micronutrient fertilizer. The preparation methods for the functional additives and inorganic micronutrient fertilizer are described in Example 1.

[0044] Comparative Example 2: The difference between this comparative example and Example 1 is that biopolysaccharides (chitosan oligosaccharides + chitosan) and bio-based sugar alcohols (sorbitol) were not used in the preparation of the liquid slow-release micronutrient fertilizer. The specific preparation method is as follows: The eutectic solvent, functional additives, inorganic micronutrient fertilizer, and water were mixed in a mass ratio of 5:5:60:50, stirred at 600 rpm until homogeneous, and then heated to 80°C for 40 min. The reaction product was collected to obtain the liquid slow-release micronutrient fertilizer. The preparation methods of the eutectic solvent, functional additives, and inorganic micronutrient fertilizer were the same as in Example 1.

[0045] Comparative Example 3: The difference between this comparative example and Example 1 is that the eutectic solvent (choline chloride, glycerol, and betaine) was not used in the preparation of the liquid slow-release micronutrient fertilizer. The specific preparation method is as follows: Biopolysaccharide, bio-based sugar alcohol, functional additives, inorganic micronutrient fertilizer, and water were mixed in a ratio of 0.3:18:5:60:50, stirred at 600 rpm until homogeneous, and heated to 80°C for 40 min. The reaction product was collected to obtain the liquid slow-release micronutrient fertilizer. The preparation methods for biopolysaccharide, bio-based sugar alcohol, functional additives, and inorganic micronutrient fertilizer were the same as in Example 1.

[0046] Experimental Example 1: Solubility Following the methods of Example 1 and Comparative Examples 1-3, each raw material was added to distilled water, stirred at 600 rpm until homogeneous, heated to 80°C for 40 min, and allowed to stand at room temperature for 1 h. The supernatant was then taken, and the ion concentration in the supernatant was determined by inductively coupled plasma mass spectrometry (ICP-MS). The results are shown in Table 1.

[0047] Table 1. Solubility of different elements in the micronutrient fertilizers prepared in Example 1 and Comparative Examples 1-3 As shown in Table 1, the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer prepared by the chelation system constructed using bio-polysaccharides, bio-based sugar alcohols, and eutectic solvents in this invention exhibits excellent solubility for micronutrients B, Mg, and Mn. In particular, the poorly soluble borax shows extremely high solubility; the amount added according to Example 1 can completely dissolve the added borax, and the solution remains clear after cooling to room temperature. In Comparative Example 1, no bio-polysaccharides, bio-based sugar alcohols, or eutectic solvents were used; only water was used as the solvent, resulting in extremely low solubility. Although borax, manganese sulfate, and all of the magnesium chloride could be dissolved when heated to 80°C, after standing at room temperature for 1 hour, the added borax and some manganese sulfate precipitated to the bottom of the beaker at room temperature, and the final clear liquid solubility was far lower than that of Example 1. The results indicate that using only water to dissolve micronutrients cannot achieve uniform dissolution. In Comparative Example 2, no biopolysaccharides or biosaccharides were used; only a eutectic solvent was employed. This effectively increased the magnesium and manganese content in the solution, but the effect on boron was not significant. In Comparative Example 3, no eutectic solvent was used; only biopolysaccharides and biosaccharides were employed. Compared to Comparative Example 1, this significantly improved the solubility of boron.

[0048] This invention employs a combination of "biopolysaccharide + biosaccharide alcohol" and "eutectic solvent," which has a synergistic effect in improving the solubility of boron and manganese and increasing the total content of trace elements. Specifically, compared to Comparative Example 1, the boron content in Comparative Examples 2 and 3 increased by 13.3 g / L and 48.4 g / L, respectively; the manganese content increased by 6.6 g / L and 5.7 g / L, respectively; and the total content of trace elements increased by 20.8 g / L and 52.6 g / L, respectively. This invention, using a combination of biopolysaccharide, biosaccharide alcohol, and eutectic solvent, increased the boron content by 63.3 g / L, the manganese content by 14.4 g / L, and the total content of trace elements by 75.3 g / L.

[0049] Test Example 2: Sustained-release performance The slow-release performance of the liquid slow-release micronutrient fertilizers prepared in Example 1 and Comparative Examples 1-3 was tested, and the results are as follows: Figure 1 As shown. The specific steps are as follows: 0.25g of liquid slow-release micronutrient fertilizer was dropped onto a glass slide and dried to constant weight in a 60℃ oven. The slide containing the dried liquid fertilizer was then placed in 30mL of water. The dissolution of the dried liquid fertilizer was observed at room temperature (25℃). The time after the fertilizer completely dissolved from the slide was recorded as the leaching time. The leaching amounts of boron and manganese in the solution were detected using ICP-MS, and the leaching rates of boron and manganese were calculated. Since magnesium chloride has good solubility, it was not necessary to determine the slow-release performance of magnesium.

[0050] Since the fertilizer added to the glass slide has a certain color, when there is no color residue on the glass slide and the water flows smoothly over the surface of the glass slide after it is removed, it is considered that the fertilizer has completely dissolved from the glass slide.

[0051] Leaching rate refers to the amount of boron or manganese leached out as a percentage of the total boron or manganese content in the dried liquid fertilizer on the glass slide.

[0052] Depend on Figure 1 It can be seen that the slow-release micronutrient fertilizers prepared in Example 1 and Comparative Examples 1-3 exhibit significant differences in their slow-release performance in water. Specifically, the liquid slow-release micronutrient fertilizer prepared in Example 1 using bio-based sugar alcohols, biopolysaccharides, and eutectic solvents as raw materials showed a leaching time of 69 min in water, with final leaching rates of 99.4% for B and 99.0% for Mn. These results indicate that it possesses good slow-release performance while maintaining good solubility, making it easily utilized by plants. Comparative Example 1, which did not use bio-based sugar alcohols, biopolysaccharides, or eutectic solvents, showed that after the micronutrients were dried on a glass slide, manganese sulfate underwent oxidation and precipitation, resulting in a leaching time of 107 min. However, the leaching rate of Mn was only 12.3%, and the leaching rate of B was only 57.2%. This indicates that boron and manganese in this system, lacking the dispersion and protection of a chelating network, are easily oxidized and precipitated in the environment, leading to nutrient fixation and reduced product effectiveness, which is detrimental to plant absorption. In Comparative Example 2, the liquid slow-release micronutrient fertilizer prepared using only a eutectic solvent as a raw material had a leaching time of 4.0 min, a B leaching rate of 63.9%, and a Mn leaching rate of 39.1%. This system showed weak nutrient slow-release capacity, and manganese sulfate also underwent some degree of oxidation. In Comparative Example 3, the liquid slow-release micronutrient fertilizer prepared using only biopolysaccharides as a raw material had a leaching time of 7 min, a B leaching rate of 77.2%, and a Mn leaching rate of 96.1%. Furthermore, according to... Figure 1 It can be seen that the present invention has a synergistic effect in improving the leaching rate of boron in liquid slow-release micronutrient fertilizers by utilizing bio-sugar alcohols, bio-polysaccharides, and eutectic solvents.

[0053] Experimental Example 3: Crop Stress Resistance Select uniformly sized and vigorous rice seeds, disinfect them with 5% NaClO solution for 10 minutes with constant stirring, then soak and rinse them 5-7 times with deionized water. After disinfection, soak the rice seeds in deionized water for 24 hours, then wipe them clean and sow them in covered petri dishes lined with two layers of filter paper, with 10 mL of diluted bio-based sugar alcohol chelated liquid micronutrient fertilizer added. Sow 30 seeds per dish, and set up 3 replicates for each treatment.

[0054] Drought stress was simulated using an 18% PEG-6000 solution, with 10 mL added to each dish. The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer prepared in Example 1 was diluted 3000 times and used as the treatment solution. A total of four treatments were set up in this experiment: water treatment and treatment solution treatment under normal conditions, and water treatment and treatment solution treatment under drought conditions. The amount of treatment solution added to the culture medium of each treatment group was 10 mL. The treated plants were placed in an incubator at 25°C and cultured in the dark. Germination rate and root length were recorded on the 7th day. The results are shown in Table 2.

[0055] The formula for calculating the germination rate is as follows: Germination rate = (Number of seeds germinated on the seventh day / Total number of seeds) × 100%.

[0056] Table 2. Germination rate and root length of rice under different treatments under normal and drought conditions. As shown in Table 2, under normal conditions, the germination rate of rice treated with water was 90.0%, and the root length was 1.48 cm. After treatment with the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer prepared according to this invention, the germination rate of rice increased by 5.6%, and the root length increased by 0.65 cm. This demonstrates that under the action of sugar alcohol and a eutectic solvent, micronutrients are more easily absorbed by rice, which helps to improve seed vigor and early root development.

[0057] Meanwhile, under drought conditions, the germination rate of rice treated with clean water was only 47.8%, and the root length was only 0.19 cm. Under the same conditions, after treatment with the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer prepared according to this invention, the germination rate of rice increased by 15.5%, and the root length increased by 0.49 cm. Therefore, the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer prepared according to this invention can significantly improve the germination rate of rice seeds and promote root elongation under drought stress.

[0058] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer, characterized in that, The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer is prepared by mixing biopolysaccharide, bio-based sugar alcohol, eutectic solvent, functional additives, and inorganic micronutrient fertilizer in a mass ratio of (0.1-20):(1-182):(0.5-25):(0.01-5):(1-220). The biopolysaccharide is one or more of chitosan, fucoidan, chitosan oligosaccharide, trehalose, and chitin oligosaccharide, and the bio-based sugar alcohol is one or more of xylitol, sorbitol, mannitol, maltitol, and euonymus alcohol.

2. The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer as described in claim 1, characterized in that, The eutectic solvent is prepared by mixing hydrogen bond acceptors and hydrogen bond donors in a mass ratio of 1:(0.01-25); The hydrogen bond acceptor is selected from choline chloride, betaine hydrochloride, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, benzyltriethylammonium chloride, triethylamine hydrochloride, decyldimethylammonium chloride, tetradecyldimethylbenzylammonium chloride, and dodecyldimethylbenzylammonium chloride. The hydrogen bond donor is selected from at least one of betaine, proline, glutamic acid, alanine, glycine, serine, polyglutamic acid, urea, oxalic acid, lactic acid, gallic acid, vitamin C, tannic acid, melatonin, hydroquinone, and glycerol.

3. The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer as described in claim 1, characterized in that, The functional additive is prepared by mixing pH adjuster, dispersant and anti-erosion agent in a mass ratio of (0.1-16):(0.1-54):(0.5-22); pH adjusters include one or more of the following: hydrochloric acid, sulfuric acid, phosphoric acid, citric acid, oxalic acid, acetic acid, malic acid, sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate. Dispersants include one or more of alkyl polysaccharide glycosides, fatty alcohol polyoxyethylene ethers, Tween, sodium dodecylbenzene sulfonate, ethoxylated modified trisiloxanes, triethanolamine, and polyoxyethylene fatty acid esters; Anti-erosion agents include one or more of the following: polyether-modified trisiloxane, polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, starch, xanthan gum, and sodium carboxymethyl cellulose.

4. The bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer as described in claim 1, characterized in that, Inorganic micronutrient fertilizers include one or more of the following: boron fertilizer, zinc fertilizer, iron fertilizer, copper fertilizer, molybdenum fertilizer, manganese fertilizer, selenium fertilizer, magnesium fertilizer, and calcium fertilizer. Boron fertilizer is one or more of boric acid, borax, and disodium octaborate tetrahydrate; zinc fertilizer is one or more of zinc sulfate monohydrate, zinc sulfate, zinc chloride, zinc oxide, zinc sulfide, and zinc phosphate; iron fertilizer is one or more of ferrous sulfate, ferrous sulfate, ferrous oxide, ferrous phosphate monohydrate, ferrous ammonium sulfate, and ferrous carbonate; copper fertilizer is one or more of copper sulfate, basic copper sulfate, copper chloride, copper oxide, cuprous oxide, and copper-containing slag; molybdenum fertilizer is one or more of ammonium molybdate, sodium molybdate, and molybdenum trioxide; manganese fertilizer is one or more of manganese sulfate, manganese carbonate, manganese chloride, and manganese oxide; selenium fertilizer is sodium selenate and / or sodium selenite; magnesium fertilizer is one or more of magnesium sulfate, magnesium chloride, and magnesium nitrate; and calcium fertilizer is calcium chloride and / or calcium nitrate.

5. The method for preparing the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer according to any one of claims 1-4, characterized in that, Includes the following steps: Biopolysaccharide, bio-based sugar alcohol, inorganic micronutrient fertilizer, functional additives, eutectic solvent and water are mixed and stirred evenly, then heated to react, and the reaction product is collected, which is the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer.

6. The method for preparing the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer as described in claim 5, characterized in that, The mass ratio of biopolysaccharide to water is (0.1-20):50, the stirring speed is 300-800 rpm, the heating temperature is 40-80℃, and the reaction time is 15-60 min.

7. The application of the bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer according to any one of claims 1-4 in agricultural planting.

8. The application as described in claim 7, characterized in that, The application methods include at least one of the following (1)-(4): (1) Spraying after dilution: Dilute the above-mentioned bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer with water to obtain a diluted solution, and spray the diluted solution on the leaves or stems of the crop. (2) Apply after making into granules: Add the above-mentioned bio-based sugar alcohol chelated liquid slow-release trace element fertilizer to the base fertilizer, mix and granulate to make granules before application; (3) Apply after preparation as controlled-release fertilizer: Apply the above-mentioned bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer to the inner matrix or the outer controlled-release membrane to form controlled-release fertilizer before application. (4) Drip irrigation mixed application: After mixing the above-mentioned bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer and liquid fertilizer, add it to the drip irrigation system for drip irrigation application.

9. The application as described in claim 8, characterized in that, In application method (1), the dilution ratio is 50-1000 times, the spraying time is from the seedling stage of the crop to before harvest or when the crop shows nutrient deficiency symptoms; the spraying frequency is once every 7-15 days, for a total of 2 sprays; the amount of each spray is 50-150L / mu; In application method (2), the base fertilizer includes one or more of urea, compound fertilizer, potassium fertilizer or phosphate fertilizer; the amount of micronutrient fertilizer added in bio-based sugar alcohol chelated liquid slow release is 0.5%-5% of the mass of the base fertilizer.

10. The application as described in claim 8, characterized in that, In application method (3), the spraying temperature is 40-70℃; the amount of inner matrix sprayed is 1%-3% of the mass of controlled-release fertilizer; the amount of outer controlled-release film sprayed is 0.5%-2% of the total mass of controlled-release fertilizer. In application method (4), the mass ratio of bio-based sugar alcohol chelated liquid slow-release micronutrient fertilizer to liquid fertilizer is 1:(10-50).

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