High-activity humic acid liquid water-soluble fertilizer and preparation method thereof

Abstract

The invention relates to the technical field of fertilizers, in particular to a high-activity humic acid liquid water-soluble fertilizer and a preparation method thereof.The high-activity humic acid liquid water-soluble fertilizer is prepared from, by mass, 45-50 parts of a humic acid compound, 14-18 parts of loaded particles, 1-1.5 parts of sodium polyglutamate, 0.5-1 part of a chelating agent glutamic acid N, N-diacetic acid and 1.5-2.5 parts of modified polyethylene glycol methyl ether methacrylate, according to the invention, through the technical scheme of enzymolysis activation of humic acid composite stress-resistant substances, dual-carrier embedding of probiotics and nano homogenization of a block dispersant, compared with the prior art, the biological activity and stress-resistant function of the humic acid are remarkably improved, long-acting slow release and rhizosphere targeted colonization of the probiotics are realized, a high-salt stable system is constructed, and the biological activity and stress-resistant function of the humic acid are improved; the method has wide application prospects in saline-alkali soil improvement, facility agriculture water and fertilizer integration and organic fruit and vegetable planting.

Description

Technical Field

[0001] This invention relates to the field of fertilizer technology, and in particular to a highly active humic acid liquid water-soluble fertilizer and its preparation method. Background Technology

[0002] Highly active humic acid liquid water-soluble fertilizer is a liquid fertilizer made by combining weathered coal, lignite, etc. as humic acid sources with functional additives after activation treatment. It mainly utilizes humic acid to promote crop root development, enhance nutrient absorption, and improve soil structure. Therefore, in the context of green transformation of agriculture, highly active humic acid liquid water-soluble fertilizer has attracted much attention because it has the dual functions of soil improvement and crop growth promotion.

[0003] In existing technologies, traditional humic acid extraction processes struggle to fully release its bioactivity. Key functional groups such as carboxyl and phenolic hydroxyl groups in the molecular structure fail to dissociate effectively, limiting its growth-promoting effect. Furthermore, the active substances added to enhance its functionality lack stability in high-salt liquid environments, easily leading to inactivation or sedimentation. Additionally, the compatibility defects of humic acid colloids with electrolytes, pesticides, and other substances further restrict its application in compound fertilization scenarios. Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop a highly active humic acid liquid water-soluble fertilizer and its preparation method. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a highly active humic acid liquid water-soluble fertilizer and its preparation method, so as to solve the problems of insufficient humic acid activity, easy inactivation of functional components and poor system compatibility in the prior art.

[0005] To achieve the above objectives, the present invention provides a highly active humic acid liquid water-soluble fertilizer and its preparation method.

[0006] A highly active humic acid liquid water-soluble fertilizer is composed of the following components in parts by weight: 45-50 parts of humic acid complex, 14-18 parts of loaded granules, 1-1.5 parts of sodium polyglutamate, 0.5-1 parts of chelating agent N,N-diacetic acid glutamate, 1.5-2.5 parts of modified polyethylene glycol methyl ether methacrylate, 0.1-0.3 parts of xanthan gum, 2.5-3.5 parts of propylene glycol, 0.1-0.2 parts of potassium sorbate, and 125-130 parts of deionized water.

[0007] Preferably, the preparation steps of the humic acid complex are as follows: Step A1: Add weathered coal powder to deionized water, stir evenly, add cellulase and xylanase, heat to 40-50℃, enzymatically hydrolyze for 3-5 hours, add potassium hydroxide, heat to 55-65℃, introduce air, activate for 1.5-2.5 hours, the reaction is complete, filter, and obtain activated humic acid extract. Step A2: Add seaweed extract, L-proline and glycine betaine to activated humic acid extract, heat to 40-60℃, and stir for 1.5-2.5 hours to obtain humic acid complex.

[0008] Cellulase and xylanase degrade the macromolecular chain of humic acid, releasing active groups. At the same time, potassium hydroxide oxidation further opens the aromatic ring structure and enhances electron transfer ability. In addition, seaweed extract can provide antioxidant protection, and L-proline and glycine betaine osmotically regulate cell sap concentration. The three of them, together with activated humic acid, form a "humic acid-biostimulant" synergy through hydrogen bonding and hydrophobic interaction.

[0009] Preferably, the mass ratio of weathered coal powder, cellulase, xylanase to potassium hydroxide in step A1 is 1:0.02-0.03:0.008-0.012:0.04-0.06; The mass ratio of seaweed extract, L-proline, glycine betaine and activated humic acid extract in step A2 is 0.08-0.012:0.02-0.03:0.04-0.06:1.

[0010] Preferably, the preparation steps of the seaweed extract in step A2 are as follows: Step B1: Under a nitrogen atmosphere, add the *Alternaria buergeriana* powder to deionized water, add 0.1 mol / L citric acid, adjust the pH to 5-5.5, heat to 40-50℃, add cellulase, and hydrolyze for 80-100 min. Then add alginate lyase and xylanase, and hydrolyze for 100-140 min. Once the reaction is complete, the enzymatic hydrolysate is obtained. Step B2: Add disodium ethylenediaminetetraacetate to the enzymatic hydrolysate, heat to 50-60℃, react for 50-70 min, heat to 65-75℃, add 60% ethanol, extract for 40-50 min, finally heat to 80-90℃, react for 8-12 min, centrifuge, filter, and distill under reduced pressure to obtain seaweed extract.

[0011] Preferably, the mass ratio of *Alternaria buergeriana* powder, deionized water, cellulase, alginate lyase and xylanase in step B1 is 1:3.8-4.2:0.0002-0.0004:0.0001-0.0003:0.00012-0.00013; In step B2, the mass ratio of disodium ethylenediaminetetraacetate, enzymatic hydrolysate, and ethanol is 0.004-0.006:1:0.58-0.62.

[0012] Preferably, the preparation steps of the supported particles are as follows: Step C1: Add nano-diatomaceous earth to a 5% citric acid solution, soak for 50-70 minutes, rotate at 150-250 rpm, filter, wash with deionized water until pH reaches 6.8-7.2, dry, and obtain acidified diatomaceous earth; Step C2: Add acidified diatomaceous earth and chitosan to deionized water, heat to 35-45℃, ultrasonically disperse for 20-40 min, heat to 50-60℃, dry for 160-200 min, pulverize and pass through a 200-mesh sieve to obtain the carrier; Step C3: Add plant lactobacillus powder to 3% sodium alginate solution, mix well, add 2% calcium chloride solution, cool to 2-6℃, stir at 40-60 rpm, solidify for 20-40 min, wash, add carrier, place in fluidized bed, heat to 30-40℃, dry for 80-100 min, sieve to obtain loaded particles.

[0013] Acidified diatomaceous earth adsorbs chitosan oligosaccharides, forming a positively charged surface that enhances the binding force with negatively charged roots. At the same time, chitosan oligosaccharides act as prebiotics to continuously nourish microorganisms, and low-temperature CaCl2 cross-linking forms a gel network that can encapsulate *Lactobacillus plantarum* in a pH-buffered microenvironment, isolating it from high-salt fertilizer damage and improving the survival rate of live bacteria.

[0014] Preferably, the mass ratio of the nano-diatomaceous earth to the citric acid solution in step C1 is 1:9.8-10.2; The mass ratio of acidified diatomaceous earth to chitosan in step C2 is 1:0.24-0.26; The mass ratio of *Lactobacillus plantarum* powder, sodium alginate solution, calcium chloride solution, and carrier in step C3 is 0.24-0.26:4.8-5.2:24-26:1.

[0015] Preferably, the preparation steps of the modified polyethylene glycol methyl ether methacrylate are as follows: Under a nitrogen atmosphere, polyethylene glycol methyl ether methacrylate, methacrylic acid, and chain transfer agent 4-cyano-4-(phenylthiothio)valerate were added to a 1,4-dioxane solvent. The mixture was heated to 60-80°C and stirred for 10-20 min. Azobisisobutyronitrile was added, and the reaction was carried out for 5-7 h. Ethyl acrylate was added, and the reaction was carried out for 7-9 h. After the reaction was completed, the mixture was cooled to 3-7°C, hydroquinone was added, and the mixture was stirred for 8-12 min. The mixture was then purified by precipitation, dried and neutralized, and distilled under reduced pressure to obtain modified polyethylene glycol methyl ether methacrylate.

[0016] Polyethylene glycol methyl ether methacrylate provides long-chain steric hindrance, while ethyl acrylate can anchor humic acid particles. In addition, N,N-diacetic acid glutamate chelates polyvalent metal ions to prevent humic acid flocculation. Furthermore, xanthan gum forms a shear-thinning fluid, inhibiting particle sedimentation and improving its storage stability.

[0017] Preferably, the mass ratio of polyethylene glycol methyl ether methacrylate, methacrylic acid, chain transfer agent, azobisisobutyronitrile, ethyl acrylate and hydroquinone is 1:0.48-0.52:0.032-0.034:0.0082-0.0084:0.15-0.17:0.0015-0.0017.

[0018] A method for preparing a highly active humic acid liquid water-soluble fertilizer, the preparation method being as follows: Add the humic acid complex to the reactor, heat to 35-45℃, add polyglutamic acid, chelating agent N,N-diacetic acid glutamic acid, and modified polyethylene glycol methyl ether methacrylate, stir for 50-70 min at 100-200 rpm, add the loaded particles, stir for 15-25 min, add xanthan gum, propylene glycol, potassium sorbate, and deionized water, stir evenly, add 10% potassium hydroxide solution, adjust the pH to 6.1-6.5, stir for 30-50 min, place in a high-pressure homogenizer, pressurize at 80 MPa, and cycle 3 times to obtain a highly active humic acid liquid water-soluble fertilizer.

[0019] The beneficial effects of this invention are: This invention provides a highly active humic acid liquid water-soluble fertilizer and its preparation method. Compared with existing technologies, this invention significantly enhances the biological activity and stress resistance function of humic acid by enzymatically activating humic acid complex stress-resistant substances, encapsulating probiotics with dual carriers, and using block dispersant nano-homogenization technology. It achieves long-term slow release and rhizosphere targeted colonization of probiotics and constructs a high-salt stable system. It has broad application prospects in saline-alkali land improvement, integrated water and fertilizer management in facility agriculture, and organic fruit and vegetable cultivation. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0021] The Lactiplantibacillus plantarum strain used in this invention is LP-14, with the accession number CGMCC No. 30841. Example 1: The preparation steps of seaweed extract are as follows: S1: Under a nitrogen atmosphere, add 100g of *Alternaria buergeriana* powder to 380g of deionized water, add 0.1mol / L citric acid, adjust the pH to 5-5.5, heat to 40℃, add 0.02g of cellulase, and enzymatically hydrolyze for 100min. Then add 0.01g of alginate lyase and 0.012g of xylanase, and enzymatically hydrolyze for 140min. Once the reaction is complete, the enzymatic hydrolysate is obtained. S2: Add 0.4g of disodium ethylenediaminetetraacetate to 100g of enzymatic hydrolysate, heat to 50℃, react for 70min, heat to 65℃, add 58g of 60% ethanol, extract for 50min, finally heat to 90℃, react for 8min, centrifuge, filter, and distill under reduced pressure to obtain seaweed extract.

[0022] Example 2: The preparation steps of seaweed extract are as follows: S1: Under a nitrogen atmosphere, add 100g of *Alternaria buergeriana* powder to 400g of deionized water, add 0.1mol / L citric acid, adjust the pH to 5-5.5, heat to 45℃, add 0.03g of cellulase, and enzymatically hydrolyze for 90min. Then add 0.02g of alginate lyase and 0.0125g of xylanase, and enzymatically hydrolyze for 120min. Once the reaction is complete, the enzymatic hydrolysate is obtained. S2: Add 0.5g of disodium ethylenediaminetetraacetate to 100g of enzymatic hydrolysate, heat to 55℃, react for 60min, heat to 70℃, add 60g of 60% ethanol, extract for 45min, finally heat to 85℃, react for 10min, centrifuge, filter, and distill under reduced pressure to obtain seaweed extract.

[0023] Example 3: The preparation steps of seaweed extract are as follows: S1: Under a nitrogen atmosphere, add 100g of *Alternaria buergeriana* powder to 420g of deionized water, add 0.1mol / L citric acid, adjust the pH to 5-5.5, heat to 50℃, add 0.04g of cellulase, and enzymatically hydrolyze for 80min. Then add 0.03g of alginate lyase and 0.013g of xylanase, and enzymatically hydrolyze for 140min. Once the reaction is complete, the enzymatic hydrolysate is obtained. S2: Add 0.6g of disodium ethylenediaminetetraacetate to 100g of enzymatic hydrolysate, heat to 60℃, react for 50min, heat to 75℃, add 62g of 60% ethanol, extract for 40min, finally heat to 90℃, react for 8min, centrifuge, filter, and distill under reduced pressure to obtain seaweed extract.

[0024] Example 4: The preparation steps of the humic acid complex are as follows: S1: Add 100g of weathered coal powder to 200mL of deionized water, stir well, add 2g of cellulase and 0.8g of xylanase, heat to 40℃, enzymatically hydrolyze for 5h, add 4g of potassium hydroxide, heat to 55℃, introduce air, activate for 2.5h, the reaction is complete, filter, and obtain activated humic acid extract. S2: Add 8g of seaweed extract (Example 1), 2g of L-proline and 4g of glycine betaine to 100g of activated humic acid extract, heat to 40°C and stir for 2.5h to obtain humic acid complex.

[0025] Example 5: The preparation steps of the humic acid complex are as follows: S1: Add 100g of weathered coal powder to 200mL of deionized water, stir well, add 2.5g of cellulase and 1g of xylanase, heat to 45℃, enzymatically hydrolyze for 4h, add 5g of potassium hydroxide, heat to 60℃, introduce air, activate for 2h, the reaction is complete, filter, and obtain activated humic acid extract. S2: Add 1.2g of seaweed extract (Example 2), 2.5g of L-proline and 5g of glycine betaine to 100g of activated humic acid extract, heat to 50°C, and stir for 2 hours to obtain humic acid complex.

[0026] Example 6: The preparation steps of the humic acid complex are as follows: S1: Add 100g of weathered coal powder to 200mL of deionized water, stir well, add 3g of cellulase and 1.2g of xylanase, heat to 50℃, enzymatically hydrolyze for 3h, add 6g of potassium hydroxide, heat to 65℃, introduce air, activate for 1.5h, the reaction is complete, filter, and obtain activated humic acid extract. S2: Add 1.2g of seaweed extract (Example 3), 3g of L-proline and 6g of glycine betaine to 100g of activated humic acid extract, heat to 60℃ and stir for 1.5h to obtain humic acid complex.

[0027] Example 7: The preparation steps of the supported particles are as follows: S1: Add 100g of nano diatomaceous earth to 980g of 5% citric acid solution, soak for 50min, rotate at 250rpm, filter, wash with deionized water until pH reaches 6.8-7.2, dry to obtain acidified diatomaceous earth; S2: Add 100g of acidified diatomaceous earth and 24g of chitosan to 200mL of deionized water, heat to 35℃, ultrasonically disperse for 40min, heat to 50℃, dry for 200min, pulverize and pass through a 200-mesh sieve to obtain the carrier. S3: Add 2.4g of plant lactobacillus powder to 48g of 3% sodium alginate solution, mix well, add 240g of % calcium chloride solution, cool to 2℃, stir at 60rpm, solidify for 20min, wash, add 10g of carrier, place in a fluidized bed, heat to 40℃, dry for 80min, sieve to obtain loaded particles.

[0028] Example 8: The preparation steps of the supported particles are as follows: S1: Add 100g of nano diatomaceous earth to 1000g of 5% citric acid solution, soak for 60min, rotate at 200rpm, filter, wash with deionized water until pH reaches 6.8-7.2, dry to obtain acidified diatomaceous earth; S2: Add 100g of acidified diatomaceous earth and 25g of chitosan to 200mL of deionized water, heat to 40℃, ultrasonically disperse for 30min, heat to 55℃, dry for 180min, pulverize and pass through a 200-mesh sieve to obtain the carrier. S3: Add 2.5g of plant lactobacillus powder to 50g of 3% sodium alginate solution, mix well, add 250g of 2% calcium chloride solution, cool to 4℃, stir at 50rpm, solidify for 30min, wash, add 100g of carrier, place in a fluidized bed, heat to 35℃, dry for 90min, sieve to obtain loaded particles.

[0029] Example 9: The preparation steps of the supported particles are as follows: S1: Add 100g of nano diatomaceous earth to 1020g of 5% citric acid solution, soak for 70min, rotate at 150rpm, filter, wash with deionized water until pH reaches 6.8-7.2, dry to obtain acidified diatomaceous earth; S2: Add 100g of acidified diatomaceous earth and 26g of chitosan to 200mL of deionized water, heat to 45℃, ultrasonically disperse for 20min, heat to 60℃, dry for 160min, pulverize and pass through a 200-mesh sieve to obtain the carrier. S3: Add 2.6g of plant lactobacillus powder to 52g of 3% sodium alginate solution, mix well, add 260g of 2% calcium chloride solution, cool to 6℃, stir at 40rpm, solidify for 40min, wash, add 10g of carrier, place in a fluidized bed, heat to 30℃, dry for 80-100min, sieve to obtain loaded particles.

[0030] Example 10: The preparation steps of modified polyethylene glycol methyl ether methacrylate are as follows: Under a nitrogen atmosphere, 100 g of polyethylene glycol methyl ether methacrylate, 48 g of methacrylic acid, and 3.2 g of chain transfer agent 4-cyano-4-(phenylthiothio)valerate were added to 200 mL of 1,4-dioxane solvent. The mixture was heated to 60 °C and stirred for 20 min. Then, 0.82 g of azobisisobutyronitrile was added, and the reaction was allowed to proceed for 5 h. Finally, 15 g of ethyl acrylate was added, and the reaction was allowed to proceed for 9 h until the reaction was complete. The mixture was then cooled to 3 °C, and 0.15 g of hydroquinone was added. The mixture was stirred for 8 min, precipitated, purified, dried, neutralized, and distilled under reduced pressure to obtain modified polyethylene glycol methyl ether methacrylate.

[0031] Example 11: The preparation steps of modified polyethylene glycol methyl ether methacrylate are as follows: Under a nitrogen atmosphere, 100 g of polyethylene glycol methyl ether methacrylate, 50 g of methacrylic acid, and 3.3 g of chain transfer agent 4-cyano-4-(phenylthiothio)valerate were added to 200 mL of 1,4-dioxane solvent. The mixture was heated to 60 °C and stirred for 20 min. Then, 0.83 g of azobisisobutyronitrile was added, and the reaction was allowed to proceed for 6 h. Finally, 16 g of ethyl acrylate was added, and the reaction was allowed to proceed for 8 h. Once the reaction was complete, the mixture was cooled to 5 °C, and 0.16 g of hydroquinone was added. The mixture was stirred for 10 min, precipitated, purified, dried, neutralized, and then distilled under reduced pressure to obtain modified polyethylene glycol methyl ether methacrylate.

[0032] Example 12: The preparation steps of modified polyethylene glycol methyl ether methacrylate are as follows: Under a nitrogen atmosphere, 100 g of polyethylene glycol methyl ether methacrylate, 52 g of methacrylic acid, and 3.4 g of chain transfer agent 4-cyano-4-(phenylthiothio)valerate were added to 200 mL of 1,4-dioxane solvent. The mixture was heated to 80 °C and stirred for 10 min. Then, 0.84 g of azobisisobutyronitrile was added, and the reaction was allowed to proceed for 7 h. Finally, 17 g of ethyl acrylate was added, and the reaction was allowed to proceed for another 7 h. Once the reaction was complete, the mixture was cooled to 7 °C, and 0.17 g of hydroquinone was added. The mixture was stirred for 8 min, precipitated, purified, dried, neutralized, and then distilled under reduced pressure to obtain modified polyethylene glycol methyl ether methacrylate.

[0033] Example 13: A method for preparing a highly active humic acid liquid water-soluble fertilizer Add 45g of humic acid complex (Example 4) to a reaction vessel, heat to 35℃, add 1g of sodium polyglutamate, 0.5g of chelating agent N,N-diacetic acid glutamate and 1.5g of modified polyethylene glycol methyl ether methacrylate (Example 10), stir for 50min at 200rpm, add 14g of loaded particles (Example 7), stir for 15min, add 0.1g of xanthan gum, 2.5g of propylene glycol, 0.1g of potassium sorbate and 125g of deionized water, stir evenly, add 10% potassium hydroxide solution, adjust pH to 6.1-6.5, stir for 30-50min, place in a high-pressure homogenizer, pressure 80MPa, circulate 3 times to obtain highly active humic acid liquid water-soluble fertilizer.

[0034] Example 14: A method for preparing a highly active humic acid liquid water-soluble fertilizer 47g of humic acid complex (Example 5) was added to a reaction vessel and heated to 40°C. 1.3g of sodium polyglutamate, 0.8g of chelating agent N,N-diacetic acid glutamate, and 2g of modified polyethylene glycol methyl ether methacrylate (Example 11) were added. The mixture was stirred for 60min at 150rpm. 16g of loaded particles (Example 8) were added and stirred for 20min. 0.2g of xanthan gum, 3g of propylene glycol, 0.15g of potassium sorbate, and 128g of deionized water were added and stirred until homogeneous. A 10% potassium hydroxide solution was added to adjust the pH to 6.1-6.5. The mixture was stirred for 40min and placed in a high-pressure homogenizer at 80MPa for 3 cycles to obtain a highly active humic acid liquid water-soluble fertilizer.

[0035] Example 15: A method for preparing a highly active humic acid liquid water-soluble fertilizer Add 50g of humic acid complex (Example 6) to a reaction vessel, heat to 45℃, add 1.5g of sodium polyglutamate, 1g of chelating agent N,N-diacetic acid glutamate and 3.5g of modified polyethylene glycol methyl ether methacrylate (Example 12), stir for 50min at 200rpm, add 18g of loaded particles (Example 9), stir for 20min, add 0.3g of xanthan gum, 3.5g of propylene glycol, 0.2g of potassium sorbate and 130g of deionized water, stir evenly, add 10% potassium hydroxide solution, adjust pH to 6.1-6.5, stir for 50min, place in a high-pressure homogenizer, pressure 80MPa, cycle 3 times to obtain highly active humic acid liquid water-soluble fertilizer.

[0036] Comparative Example 1: Compared with Example 13, this comparative example did not add cellulase and xylanase during the preparation of the humic acid complex. All other steps and parameters were the same, and will not be repeated here. The final result was a highly active humic acid liquid water-soluble fertilizer.

[0037] Comparative Example 2: This comparative example differs from Example 13 only in that the "carrier" is replaced with "ordinary diatomaceous earth". All other steps and parameters are the same, and will not be repeated here. The final result is a highly active humic acid liquid water-soluble fertilizer.

[0038] Comparative Example 3: Compared with Example 13, this comparative example only replaces "modified polyethylene glycol methyl ether methacrylate" with "sodium polyacrylate dispersant". All other steps and parameters are the same, and will not be repeated in this comparative example. The final result is a highly active humic acid liquid water-soluble fertilizer.

[0039] Comparative Example 4: Compared with Example 13, this comparative example only replaces the high-pressure homogenization pressure "80MPa" with "30MPa". All other steps and parameters are the same, and will not be repeated here. The final result is a highly active humic acid liquid water-soluble fertilizer.

[0040] Comparative Example 5: Compared with Example 13, this comparative example did not add alginate solution during the preparation of the loaded particles. All other steps and parameters were the same, and will not be repeated here. The final result was a highly active humic acid liquid water-soluble fertilizer.

[0041] Performance testing: Humic acid activity test The UV-2600 ultraviolet-visible spectrophotometer was used in accordance with the GB / T 34765-2017 testing standard. 1. Preparation of 1% sodium pyrophosphate alkaline solution: Weigh 10.0g of sodium pyrophosphate and dissolve it in 1L of distilled water. Add sodium hydroxide solution and adjust the pH to 11.0. Humic acid standards: 0 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, and 400 mg / L were prepared using pure humic acid.

[0042] 2. Take 0.500g of each of the water-soluble fertilizers from Examples 13-15 and Comparative Examples 1-5, add 50mL of 1% sodium pyrophosphate alkaline solution, heat to 60℃, shake at 150rpm for 60min, transfer to centrifuge tubes, centrifuge at 4000rpm for 10min, take the supernatant, filter, and obtain the filtrate. 3. Using sodium pyrophosphate alkaline solution as a reference, measure the absorbance (A) at a wavelength of 465 nm using an ultraviolet spectrophotometer. 4. Formula for calculating active humic acid content: kA+b: humic acid concentration in the filtrate obtained from the standard curve (mg / L); V: total volume of the extract (L); D: dilution factor; m: sample mass (g).

[0043] Table 1. Results of humic acid activity tests in the examples and comparative examples Probiotic survival rate determination Refer to GB 4789.35-2016, the standard for testing lactic acid bacteria in food microbiology. 1. Take 1.0 mL of each of the water-soluble fertilizers from Examples 13-15 and Comparative Examples 1-5, add 9.0 mL of sterile physiological saline, vortex for 30 seconds, and prepare 10 -1 The diluent was serially diluted 10-fold to 10... -7 ; 2. Select 10 -510 -6 10 -7 Three dilutions were prepared, with 0.1 mL of each sample spread onto MRS agar plates. Each dilution was replicated three times. The plates were inverted in an anaerobic incubator and incubated at 30±1℃ for 48±2 h. 3. Survival rate calculation formula: N1: viable bacteria count in finished fertilizer (CFU / mL); N0: viable bacteria count in loaded granules (CFU / mL).

[0044] Table 2. Results of probiotic survival rate determination in the examples and comparative examples. Physical stability test 1. Take 50 mL of each of the water-soluble fertilizers from Examples 13-15 and Comparative Examples 1-5, place them in stoppered test tubes, place them in an oven at 54℃ and let them stand for 7 days. Pour off the supernatant, centrifuge at 1000 rpm for 10 min, discard the supernatant, and dry at 105℃ to constant weight (mL). 2. Calculation of sedimentation rate: m0: mass of centrifuge tube (g); m1: mass of centrifuge tube + precipitate (g); m s : Total sample mass (g), 0.1 represents the percentage of precipitate suspension (5mL / 50mL); 3. Take the lower layer of precipitate, add 50 mL of deionized water, sonicate for 3 minutes, and measure with a laser particle size analyzer. Take the average D90 value after 3 measurements.

[0045] Chemical stability test The test was conducted according to ISO 13099-1:2012 standard, using a Zeta potentiometer. Take 2.0 mL of water-soluble fertilizer from Examples 13-15 and Comparative Examples 1-5 respectively, dilute it 100 times with deionized water, ultrasonically disperse it for 30 seconds, let it stand to defoam for 5 minutes, heat it to 25°C, equilibrate it for 60 seconds, and measure it ≥3 times with a Zeta potential meter.

[0046] Table 3. Results of probiotic survival rate determination in the examples and comparative examples Resilience test Referring to GB / T 29371.2-2012 Technical Specification for Identification of Crop Stress Resistance Part 2: Salt Tolerance, a light incubator was used; 1. Disinfect strawberry seeds with a 1% sodium chlorate solution for 10 minutes, sow them in a mixture of vermiculite and perlite (volume ratio 3:1), and cultivate them in a light incubator until they reach the true leaf stage; 2. Ten plants per group; control group: sprayed with clean water, normal nutrient solution; Stress group: Spray with water and 150 mmol / L NaCl nutrient solution; Normal group: Spray with water-soluble fertilizer of examples 13-15 and comparison examples 1-5, and 150 mmol / L NaCl nutrient solution; spray 5 mL / plant evenly on the leaves, once every other day, for a total of 3 times, and culture for 7 days.

[0047] 3. Take 0.2g of strawberry leaves, grind them into powder, add quartz sand and 3mL of 10% trichloroacetic acid, grind into a slurry, cool to 4℃, centrifuge at 10000rpm for 10min, take 1.5mL of supernatant, add 3mL of 0.67% thiobarbituric acid, heat to 100℃, react for 20min, cool to 0℃, react for 5min, and measure with a UV spectrophotometer; 4. Calculation formula: A 532 A 600 A 450 : Absorbance at corresponding wavelength; W: Fresh weight of sample (g); V: Volume of extract (mL); Chlorophyll retention rate determination 1. Take 0.1g of leaves, add 10mL of 80% acetone, extract in the dark for 24h until the tissue turns white, centrifuge at 4000rpm for 10min, take the supernatant, make up to 25mL, and measure with a spectrophotometer. 2. Chlorophyll formula: A 645 A 663 ; corresponding wavelength absorbance; V: extraction liquid volume (mL); W: sample fresh weight (g).

[0048] Table 4. Results of probiotic survival rate determination in the examples and comparative examples Data Analysis: As can be seen from Tables 1-4, the high-activity humic acid liquid water-soluble fertilizer prepared by the invention has higher humic acid activity, probiotic survival rate, system stability and crop stress resistance. Comparative Example 1, due to the absence of cellulase and xylanase in the humic acid preparation process, resulted in insufficient degradation of the humic acid macromolecular chain, with an activity of only 142.7 mg / g and significantly reduced stress resistance. This is because cellulase and xylanase specifically degrade the β-1,4-glycosidic bonds and xylan scaffold in the humic acid macromolecular chain, breaking the dense cross-linked structure of the humic acid-polysaccharide complex. Comparative Example 1 skipped this step, causing the humic acid to remain in the polymerized state of the original coal powder, resulting in an excessively high molecular weight. The active functional groups were encapsulated within the molecule and could not be exposed. Although subsequent potassium hydroxide oxidation could partially open the aromatic ring, the lack of enzymatic pretreatment led to significant steric hindrance in the humic acid, making it difficult for the oxidant to penetrate to the molecular core. Furthermore, the biological activity of humic acid depends on the redox activity of its aromatic ring. The lack of enzymatic hydrolysis resulted in the aromatic ring not being fully dissociated, the π-π conjugated system being incomplete, and the electron cloud density distribution being uneven. In addition, seaweed extracts, L-proline, etc. need to form a "synergistic body" with activated humic acid through hydrogen bonding and hydrophobic interactions. The humic acid in Comparative Example 1, due to its unopened structure and small specific surface area, could not effectively load stress-resistant substances. In Comparative Example 2, replacing the carrier with ordinary diatomaceous earth resulted in a sharp drop in probiotic survival rate to 38%. This was because ordinary diatomaceous earth was not acidified and had an electrically neutral surface, making it unable to form a strong electrostatic bond with chitosan. This led to loose chitosan adhesion, easy detachment during the drying process, and discontinuous chitosan coating. Consequently, the calcium alginate gel could not evenly cover the carrier-bacterial complex. Furthermore, the positively charged carrier could be directionally enriched in the rhizosphere through electrostatic interactions, forming a local "slow-release reservoir of probiotics." In contrast, the electrically neutral ordinary diatomaceous earth carrier diffused randomly in the soil, resulting in ineffective dilution of the probiotics and further weakening their biosynergistic effect. Comparative Example 3, by replacing the modified dispersant with sodium polyacrylate, resulted in a precipitation rate as high as 32.5%. This is because the modified polyethylene glycol methyl ether methacrylate contains long-chain polyethylene glycol branches, which fully extend in water to form a thick hydration layer. This steric hindrance effectively resists the van der Waals attraction of humic acid particles, preventing their aggregation. In contrast, sodium polyacrylate only has a linear short-chain structure, and its hydration layer is thinner, failing to provide an effective steric barrier. At the same time, the modified polyethylene glycol methyl ether methacrylate forms a strong π-π stack with the aromatic ring of humic acid through the hydrophobic effect of the ethyl acrylate block, achieving "point-to-point" anchoring. In addition, the exposed aromatic core of humic acid becomes more hydrophobic in a high-salt environment, forming large-sized aggregates through hydrophobic association. The modified polyethylene glycol methyl ether methacrylate actively encapsulates the aromatic core through hydrophobic blocks, blocking the association path and thus improving its stress resistance. In Comparative Example 4, the precipitation rate increased to 16.8% when the high-pressure homogenization pressure was reduced to 30 MPa. This was because the 30 MPa homogenization did not provide sufficient shear force to dismantle the multi-level structure of the particles, nor did it activate the cavitation effect to modify the interfacial properties, causing the system to fall into a triple instability trap of "excessive particle size, network collapse and hydrophobic aggregation". Comparative Example 5 had a probiotic survival rate of only 18% because sodium alginate gel was not added to the loaded particles. This was because the lack of calcium alginate gel network protection caused Lactobacillus plantarum to be directly exposed to a high-salt environment and become inactive.

[0049] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0050] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A highly active humic acid liquid water-soluble fertilizer, characterized in that, It is composed of the following components in parts by weight: 45-50 parts of humic acid complex, 14-18 parts of loaded particles, 1-1.5 parts of sodium polyglutamate, 0.5-1 parts of chelating agent N,N-diacetic acid glutamate, 1.5-2.5 parts of modified polyethylene glycol methyl ether methacrylate, 0.1-0.3 parts of xanthan gum, 2.5-3.5 parts of propylene glycol, 0.1-0.2 parts of potassium sorbate, and 125-130 parts of deionized water.

2. The highly active humic acid liquid water-soluble fertilizer according to claim 1, characterized in that, The preparation steps of the humic acid complex are as follows: Step A1: Add weathered coal powder to deionized water, stir evenly, add cellulase and xylanase, heat to 40-50℃, enzymatically hydrolyze for 3-5 hours, add potassium hydroxide, heat to 55-65℃, introduce air, activate for 1.5-2.5 hours, the reaction is complete, filter, and obtain activated humic acid extract. Step A2: Add seaweed extract, L-proline and glycine betaine to activated humic acid extract, heat to 40-60℃, and stir for 1.5-2.5 hours to obtain humic acid complex.

3. The highly active humic acid liquid water-soluble fertilizer according to claim 2, characterized in that, The mass ratio of weathered coal powder, cellulase, xylanase to potassium hydroxide in step A1 is 1:0.02-0.03:0.008-0.012:0.04-0.06; The mass ratio of seaweed extract, L-proline, glycine betaine and activated humic acid extract in step A2 is 0.08-0.012:0.02-0.03:0.04-0.06:

1.

4. The highly active humic acid liquid water-soluble fertilizer according to claim 2, characterized in that, The preparation steps of the seaweed extract described in step A2 are as follows: Step B1: Under a nitrogen atmosphere, add the *Alternaria buergeriana* powder to deionized water, add 0.1 mol / L citric acid, adjust the pH to 5-5.5, heat to 40-50℃, add cellulase, and hydrolyze for 80-100 min. Then add alginate lyase and xylanase, and hydrolyze for 100-140 min. Once the reaction is complete, the enzymatic hydrolysate is obtained. Step B2: Add disodium ethylenediaminetetraacetate to the enzymatic hydrolysate, heat to 50-60℃, react for 50-70 min, heat to 65-75℃, add 60% ethanol, extract for 40-50 min, finally heat to 80-90℃, react for 8-12 min, centrifuge, filter, and distill under reduced pressure to obtain seaweed extract.

5. The highly active humic acid liquid water-soluble fertilizer according to claim 4, characterized in that, The mass ratio of *Alternaria buergeriana* powder, deionized water, cellulase, alginate lyase, and xylanase in step B1 is 1:3.8-4.2:0.0002-0.0004:0.0001-0.0003:0.00012-0.00013; In step B2, the mass ratio of disodium ethylenediaminetetraacetate, enzymatic hydrolysate, and ethanol is 0.004-0.006:1:0.58-0.

62.

6. The highly active humic acid liquid water-soluble fertilizer according to claim 1, characterized in that, The steps for preparing the supported particles are as follows: Step C1: Add nano-diatomaceous earth to a 5% citric acid solution, soak for 50-70 minutes, rotate at 150-250 rpm, filter, wash with deionized water until pH reaches 6.8-7.2, dry, and obtain acidified diatomaceous earth; Step C2: Add acidified diatomaceous earth and chitosan to deionized water, heat to 35-45℃, ultrasonically disperse for 20-40 min, heat to 50-60℃, dry for 160-200 min, pulverize and pass through a 200-mesh sieve to obtain the carrier; Step C3: Add plant lactobacillus powder to 3% sodium alginate solution, mix well, add 2% calcium chloride solution, cool to 2-6℃, stir at 40-60 rpm, solidify for 20-40 min, wash, add carrier, place in fluidized bed, heat to 30-40℃, dry for 80-100 min, sieve to obtain loaded particles.

7. The highly active humic acid liquid water-soluble fertilizer according to claim 6, characterized in that, The mass ratio of nano-diatomaceous earth to citric acid solution in step C1 is 1:9.8-10.2; The mass ratio of acidified diatomaceous earth to chitosan in step C2 is 1:0.24-0.26; The mass ratio of *Lactobacillus plantarum* powder, sodium alginate solution, calcium chloride solution, and carrier in step C3 is 0.24-0.26:4.8-5.2:24-26:

1.

8. The highly active humic acid liquid water-soluble fertilizer according to claim 1, characterized in that, The preparation steps of the modified polyethylene glycol methyl ether methacrylate are as follows: Under a nitrogen atmosphere, polyethylene glycol methyl ether methacrylate, methacrylic acid, and chain transfer agent 4-cyano-4-(phenylthiothio)valerate were added to a 1,4-dioxane solvent. The mixture was heated to 60-80°C and stirred for 10-20 min. Azobisisobutyronitrile was added, and the reaction was carried out for 5-7 h. Ethyl acrylate was added, and the reaction was carried out for 7-9 h. After the reaction was completed, the mixture was cooled to 3-7°C, hydroquinone was added, and the mixture was stirred for 8-12 min. The mixture was then purified by precipitation, dried and neutralized, and distilled under reduced pressure to obtain modified polyethylene glycol methyl ether methacrylate.

9. A highly active humic acid liquid water-soluble fertilizer according to claim 8, characterized in that, The mass ratio of polyethylene glycol methyl ether methacrylate, methacrylic acid, chain transfer agent, azobisisobutyronitrile, ethyl acrylate and hydroquinone is 1:0.48-0.52:0.032-0.034:0.0082-0.0084:0.15-0.17:0.0015-0.0017.

10. A method for preparing a highly active humic acid liquid water-soluble fertilizer according to any one of claims 1-9, characterized in that, The preparation method is as follows: Add the humic acid complex to the reactor, heat to 35-45℃, add polyglutamic acid, chelating agent N,N-diacetic acid glutamic acid, and modified polyethylene glycol methyl ether methacrylate, stir for 50-70 min at 100-200 rpm, add the loaded particles, stir for 15-25 min, add xanthan gum, propylene glycol, potassium sorbate, and deionized water, stir evenly, add 10% potassium hydroxide solution, adjust the pH to 6.1-6.5, stir for 30-50 min, place in a high-pressure homogenizer, pressurize at 80 MPa, and cycle 3 times to obtain a highly active humic acid liquid water-soluble fertilizer.

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