Phosphorus-solubilizing biological bacterial fertilizer, preparation method thereof and application of phosphorus-solubilizing biological bacterial fertilizer to growth promotion of corn seedlings

Abstract

The invention discloses a phosphorus-solubilizing biological bacterial fertilizer, a preparation method of the phosphorus-solubilizing biological bacterial fertilizer and application of the phosphorus-solubilizing biological bacterial fertilizer to growth promotion of corn seedlings, and belongs to the technical field of biological fertilizers. The slow-release bacterial fertilizer is fixed on the porous hard biochar powder material by utilizing hydroxyl groups of the metal framework, the slow-release bacterial fertilizer is applied to soil, the sodium alginate layer wrapping the surface of the slow-release bacterial fertilizer can be gradually decomposed and slowly release phosphate-solubilizing bacteria in the slow-release bacterial fertilizer, and released organic acid can activate the metal framework serving as a bridge, so that the phosphate-solubilizing bacteria can be released; after thio-salicylic acid in the metal framework structure is in contact with organic acid, the structure collapses, phosphate groups grafted in the structure are released, phosphorus is actively supplied to plant roots, the structure collapse of the metal framework can promote the connected slow-release bacterial fertilizer to be rapidly released, and therefore rapid and long-acting supply is achieved, and growth of crops is promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of biological fertilizers, and particularly relates to a phosphorus-solubilizing biological bacterial fertilizer, a preparation method thereof, and a growth-promoting application on corn seedlings. Background Art

[0002] With the development of modern agriculture, the application amount of organic fertilizers is continuously decreasing, which ultimately leads to the continuous increase in the application amount of nitrogen and phosphorus chemical fertilizers and the gradual shortage of potassium nutrition. To obtain high yields, crops must be supplemented with phosphate fertilizers in the soil. Phosphate radicals are chemically active and will quickly react with calcium salts in alkaline soils and iron and aluminum ions in acidic soils after being applied to the soil, and then be fixed or fixed by soil colloids, converting them into ineffective states, and finally remaining in the soil in the form of insoluble phosphates or adsorbed states, which are difficult to be directly absorbed by plants. As a result, the seasonal utilization rate of phosphate fertilizers is only 10 - 25%, and 75 - 90% of the applied phosphate fertilizers are deposited in the soil, not only causing serious waste, but also leading to the accumulation of phosphorus in the soil, resulting in an imbalance in the content of various nutrient elements in the soil and affecting the overall absorption of nutrients by plants.

[0003] Phosphorus-solubilizing bacteria are a type of bacteria with the function of dissolving phosphorus, which have a great influence on the transformation and availability of soil phosphorus. Phosphorus-solubilizing bacteria are an important part of the soil and participate in the material cycle of the soil ecosystem, endowing it with the ability of dynamic nutrient conversion and sustainable plant production. They can directly promote plant growth by secreting plant growth hormones, or indirectly promote plant growth and development by producing small molecular substances such as organic acids and enzymes to activate soil substances such as insoluble phosphorus.

[0004] Chinese Patent Publication No. CN107827485B discloses a biological bacterial fertilizer, a preparation method thereof, and an application in soil phosphorus dissolution. This biological bacterial fertilizer utilizes the synergistic effect of effective microorganisms in phosphorus-solubilizing bacteria and EM bacterial liquid to make the growth effect of crops better. However, in this scheme, after the phosphorus-solubilizing bacteria are activated, inoculated, and fermented to obtain a fermentation broth, the fermentation broth is stirred and mixed with an adsorption carrier to obtain a biological bacterial fertilizer. The adsorption carrier cannot effectively fix the phosphorus-solubilizing bacteria, resulting in the premature secretion of organic acids by the phosphorus-solubilizing bacteria, and the organic acids are quickly chelated by calcium ions and iron ions in the soil before reaching the plant roots, reducing the phosphorus dissolution effect and affecting the growth of crops. Summary of the Invention

[0005] The object of the present invention is to provide a phosphorus-solubilizing bio-fertilizer, its preparation method and its growth-promoting application on corn seedlings. By using porous hard biochar powder as the matrix, a metal skeleton with phosphate groups is formed in situ on the surface, and the slow-release bio-fertilizer is fixed on the porous hard biochar powder material by using the hydroxyl groups of the metal skeleton. When applied to the soil, the sodium alginate layer wrapped on the surface of the slow-release bio-fertilizer will gradually decompose, slowly releasing the phosphorus-solubilizing bacteria therein. The released organic acids will activate the metal skeleton as a bridge. After the thiosalicylic acid in the metal skeleton structure comes into contact with the organic acids, the structure collapses, releasing the phosphate groups grafted in the structure, actively supplying phosphorus elements to the plant roots. Moreover, the collapse of the metal skeleton structure will prompt the connected slow-release bio-fertilizer to be released quickly, so as to achieve rapid and long-term supply and promote the growth of crops.

[0006] The object of the present invention can be achieved by the following technical solutions: A phosphorus-solubilizing bio-fertilizer, comprising the following components by mass: 50-60 parts of compound bio-fertilizer, 10-20 parts of humic acid, 5-10 parts of urea and 3-4 parts of potassium sulfate; Furthermore, the compound bio-fertilizer is prepared by the following steps: Add phosphorylated modified thiosalicylic acid, methanol and dimethylformamide into a reaction kettle, stir at 50-60 °C and 500-600 r / min for 30-45 min, then add 10-15 wt% ammonia water solution, ferric chloride hexahydrate and porous hard biochar powder, continue to stir and react for 1-2 h, then add the slow-release bio-fertilizer, continue to stir and react for 1-2 h, filter, wash, and dry in vacuum to obtain the compound bio-fertilizer.

[0007] Furthermore, the dosage ratio of phosphorylated modified thiosalicylic acid, methanol, dimethylformamide, ammonia water solution, ferric chloride hexahydrate, porous hard biochar powder and slow-release bio-fertilizer is 2.8-3.2 kg: 2-3 L: 4-5 L: 500-600 mL: 1-2 kg: 3-4 kg: 2-3 kg.

[0008] Furthermore, the mass ratio of the compound bio-fertilizer, humic acid, urea and potassium sulfate is 5-6: 1-2: 0.5-1: 0.3-0.4.

[0009] Furthermore, the porous hard biochar powder is prepared by the following steps: Add chitosan powder and acetic acid solution with a mass fraction of 4 - 5% into a reaction kettle, stir for 1 - 2 h under the conditions of 20 - 25 °C and 500 - 600 r / min, add formaldehyde solution with a mass fraction of 4 - 5%, continue to stir for 10 - 15 min, let it stand for 30 - 40 min after stirring, heat up to 80 - 90 °C at a rate of 10 - 12 °C / h, keep the temperature for 24 - 26 h, filter, wash the filter cake with deionized water and absolute ethanol respectively for 2 - 3 times, and dry it in vacuum at 60 - 80 °C for 1 - 2 h to obtain the precursor powder; transfer the precursor powder and epoxy resin powder to a muffle furnace, heat it to 900 - 1000 °C under a nitrogen atmosphere, keep the temperature for 2 - 3 h, and cool it naturally to obtain the porous hard biochar powder.

[0010] Further, the dosage ratio of chitosan powder, acetic acid solution and formaldehyde solution is 5 - 6 kg : 7 - 8 L : 1 - 2 L.

[0011] Further, the dosage ratio of the precursor powder and epoxy resin powder is 4 - 5 kg : 3 - 3.5 kg.

[0012] Further, phosphorylated modified thiosalicylic acid is prepared through the following steps: Add thiosalicylic acid and deionized water into a reaction kettle, stir for 10 - 15 min under the conditions of 20 - 25 °C and 500 - 600 r / min, then add 1 - aminobutylphosphonic acid, continue to stir for 1 - 2 h, then adjust the pH value to 3 - 4 with sulfuric acid solution with a mass fraction of 20 - 25%, heat up to 70 - 78 °C, dropwise add formaldehyde solution with a mass fraction of 37 - 40%, continue to react for 4 - 5 h, carry out vacuum filtration, wash the filter cake with deionized water and absolute ethanol respectively for 2 - 3 times, and dry it in vacuum at 60 - 80 °C for 1 - 2 h to obtain phosphorylated modified thiosalicylic acid.

[0013] Further, the dosage ratio of thiosalicylic acid, deionized water, 1 - aminobutylphosphonic acid, sulfuric acid solution and formaldehyde solution is 3 - 4 kg : 5 - 6 L : 4 - 5 kg : 200 - 300 mL : 4 - 5 L.

[0014] Further, the slow - release bacterial fertilizer is prepared through the following steps: Add sodium alginate and deionized water into a reaction kettle, stir for 10 - 15 min under the conditions of 20 - 25 °C and 500 - 600 r / min, then add microbial inoculum, continue to stir for 30 - 60 min, drop it into calcium chloride solution with a mass fraction of 3 - 5%, continue to stir for 1 - 2 h, filter, wash the filter cake with deionized water and absolute ethanol respectively for 2 - 3 times, and dry it in vacuum at 60 - 80 °C for 1 - 2 h to obtain the slow - release bacterial fertilizer.

[0015] Furthermore, the dosage ratio of sodium alginate, deionized water, microbial inoculum, and calcium chloride solution is 3 - 4 kg : 4 - 5 L : 1 - 2 kg : 3 - 4 L.

[0016] Furthermore, the microbial inoculum is prepared through the following steps: Inoculate Bacillus aryabhattai in NB medium, and activate and culture it in a constant temperature shaker at 150 - 200 r / min and 28 - 30 °C for 12 - 14 h to obtain an activated bacterial solution; inoculate 1 - 2 mL of the activated bacterial solution in 50 mL of NB medium, activate and culture it in a constant temperature shaker at 150 - 200 r / min and 28 - 30 °C for 24 - 26 h, centrifuge at 5000 - 6000 r / min for 10 - 12 min, discard the supernatant, resuspend the cells with sterile water, and adjust the OD600 value to 1.0 to obtain the microbial inoculum.

[0017] A preparation method of a phosphorus - solubilizing bio - fertilizer is prepared through the following steps: Add compound bio - fertilizer, humic acid, urea, and potassium sulfate into a blender according to a mass ratio of 5 - 6:1 - 2:0.5 - 1:0.3 - 0.4, and mix evenly to obtain a phosphorus - solubilizing bio - fertilizer.

[0018] The present invention also provides a growth - promoting application of the phosphorus - solubilizing bio - fertilizer on corn seedlings.

[0019] The beneficial effects of the present invention: 1. The phosphorus - solubilizing bio - fertilizer prepared by the present invention uses porous hard biochar powder as the matrix, in - situ forms a metal skeleton with phosphate groups on the surface, and uses the hydroxyl groups of the metal skeleton to fix the slow - release bio - fertilizer on the porous hard biochar powder material. When applied to the soil, it can significantly promote the growth of corn seedlings and the absorption of nutrients, and increase the content of available nutrients in the soil.

[0020] 2. The phosphorylated modified thiosalicylic acid prepared by the present invention condenses the amino group of 1 - aminobutylphosphonic acid with formaldehyde to form a hydroxymethyl intermediate. After the hydroxymethyl intermediate is deprotonated, an imine ion is generated. The imine ion attacks the carbon in the structural formula of thiosalicylic acid to form a C - N bond, connecting aminobutylphosphonic acid to the thiosalicylic acid skeleton. The sulfhydryl group on the phosphorylated modified thiosalicylic acid reacts with the carboxyl group on the surface of the porous hard biochar powder to in - situ generate a metal skeleton structure with phosphorylated modified thiosalicylic acid as the monomer on the surface of the porous hard biochar powder. The metal skeleton can further increase the surface roughness and porosity of the porous hard biochar powder. The surface porous and rough properties can improve the adhesion strength of the slow - release bio - fertilizer and increase the adhesion sites.

[0021] 3. The compound bacterial fertilizer of the present invention can bind through the carboxyl group in the thiosalicylic acid structural formula in the metal skeleton to the hydroxyl group on the sodium alginate shell wrapped on the surface of the slow-release bacterial fertilizer. The metal skeleton serves as a bridge to fix the slow-release bacterial fertilizer on the surface of the porous hard biochar powder. When applied to the soil, the sodium alginate layer wrapped on the surface of the slow-release bacterial fertilizer will gradually decompose, slowly releasing the phosphorus-solubilizing bacteria therein. The sodium alginate microspheres simultaneously encapsulate the bacterial cells and the organic acids secreted by them, preventing the organic acids from being quickly chelated and inactivated by calcium ions and iron ions in the soil, extending the phosphorus-solubilization period. The released organic acids will activate the metal skeleton serving as a bridge. The thiosalicylic acid in the metal skeleton structure is pH-responsive. After contacting the organic acids, the structure collapses, releasing the phosphate groups grafted in the structure to actively supply phosphorus elements to the plant roots. And the collapse of the metal skeleton structure will prompt the connected slow-release bacterial fertilizer to be quickly released, thereby achieving rapid and long-term supply. Detailed implementation manners

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0023] Embodiment 1: A preparation method of a phosphorus-solubilizing biological bacterial fertilizer is prepared through the following steps: S1: Inoculate Bacillus aryabhattai in NB medium, activate and culture it in a constant temperature shaker at 150 r / min and 28 °C for 12 h to obtain an activated bacterial liquid; inoculate 1 mL of the activated bacterial liquid in 50 mL of NB medium, activate and culture it in a constant temperature shaker at 150 r / min and 28 °C for 24 h, centrifuge at 5000 r / min for 10 min, discard the supernatant, resuspend the bacterial cells with sterile water, and adjust the OD600 value to 1.0 to obtain a microbial inoculant.

[0024] S2: Add 3 kg of sodium alginate and 4 L of deionized water to the reaction kettle, stir at 20 °C and 500 r / min for 10 min, then add 1 kg of the microbial inoculant, continue to stir for 30 min to obtain a mixed solution. Drop the mixed solution into 3 L of a calcium chloride solution with a mass fraction of 3%, continue to stir for 1 h, filter, wash the filter cake twice with deionized water and absolute ethanol respectively, and vacuum dry at 60 °C for 1 h to obtain a slow-release bacterial fertilizer.

[0025] Through the microcapsule effect of sodium alginate, the microbial inoculant is encapsulated, so as to achieve the purpose of slow release, avoid premature decomposition when applied to the soil, and reduce the utilization rate.

[0026] S3: Add 5 kg of chitosan powder and 7 L of acetic acid solution with a mass fraction of 4% into the reaction kettle, stir for 1 h under the conditions of 20 °C and 500 r / min, add 1 L of formaldehyde solution with a mass fraction of 4%, continue to stir for 10 min, let it stand for 30 min after stirring, heat it to 80 °C for aging at a rate of 10 °C / h, keep the temperature for 24 h, filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 60 °C for 1 h to obtain the precursor powder; transfer 4 kg of the precursor powder and 3 kg of epoxy resin powder into the muffle furnace, heat it to 900 °C under the nitrogen atmosphere, keep the temperature for 2 h, and cool it naturally to obtain the porous hard biochar powder.

[0027] In the dilute acetic acid solution, the amino groups of chitosan are protonated. After adding the formaldehyde solution, formaldehyde reacts with the amino groups of chitosan to form a Schiff base reaction, crosslink the chitosan molecular chains by forming imine bonds (C=N), and construct a three-dimensional network structure. Epoxy resin, as an auxiliary carbon source, pyrolyzes at high temperature to generate a rigid carbon skeleton, co-carbonizes with the precursor, and finally obtains the porous hard biochar powder; the porous hard biochar powder has a high specific surface area, high porosity and good roughness, and can be used as the attachment site of microbial agents.

[0028] S4: Add 3 kg of thiosalicylic acid and 5 L of deionized water into the reaction kettle, stir for 10 min under the conditions of 20 °C and 500 r / min, then add 4 kg of 1-aminobutylphosphonic acid, continue to stir for 1 h, then add 200 mL of sulfuric acid solution with a mass fraction of 20% to adjust the pH value to 3, heat it to 70 °C, dropwise add 4 L of formaldehyde solution with a mass fraction of 37%, continue to react for 4 h, carry out vacuum filtration under reduced pressure, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 60 °C for 1 h to obtain phosphorylated modified thiosalicylic acid.

[0029] The amino group of 1-aminobutylphosphonic acid condenses with formaldehyde to form a hydroxymethyl intermediate. After the hydroxymethyl intermediate is deprotonated, an imine ion is generated. The imine ion attacks the carbon in the structural formula of thiosalicylic acid to form a C-N bond, connecting the aminobutylphosphonic acid to the thiosalicylic acid skeleton.

[0030] S5: Add 2.8 kg of phosphorylated modified thiosalicylic acid, 2 L of methanol and 4 L of dimethylformamide into the reaction kettle, stir for 30 min under the conditions of 50 °C and 500 r / min, then add 500 mL of ammonia water solution with a mass fraction of 10%, 1 kg of ferric chloride hexahydrate and 3 kg of porous hard biochar powder, continue to stir and react for 1 h, then add 2 kg of slow-release bacterial fertilizer, continue to stir and react for 1 h, filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 60 °C for 1 h to obtain the compound bacterial fertilizer.

[0031] The sulfhydryl group on thiosalicylic acid is phosphorylated and reacts with the carboxyl groups on the surface of the porous hard biochar powder to in-situ generate a metal framework structure with phosphorylated thiosalicylic acid as the monomer on the surface of the porous hard biochar powder. The metal framework can further increase the surface roughness and porosity of the porous hard biochar powder. The carboxyl groups in the thiosalicylic acid structural formula in the metal framework can bind to the hydroxyl groups on the sodium alginate shell wrapped on the surface of the slow-release bacterial fertilizer. The slow-release bacterial fertilizer is fixed on the surface of the porous hard biochar powder through the metal framework as a bridge, and the surface porosity and roughness can improve the adhesion strength of the slow-release bacterial fertilizer and increase the adhesion sites.

[0032] When the compound bacterial fertilizer is applied to the soil, the sodium alginate layer wrapped on the surface of the slow-release bacterial fertilizer will gradually decompose and slowly release the phosphorus-solubilizing bacteria therein. The sodium alginate microspheres simultaneously encapsulate the bacterial cells and the organic acids secreted by them, preventing the rapid chelation and inactivation of the organic acids by calcium ions and iron ions in the soil, prolonging the phosphorus-solubilizing cycle. The released organic acids will activate the metal framework acting as a bridge. The thiosalicylic acid in the metal framework structure is pH-responsive. After contacting the organic acids, the structure collapses, releasing the phosphate groups grafted in the structure to actively supply phosphorus elements to the plant roots. Moreover, the collapse of the metal framework structure will promote the rapid release of the connected slow-release bacterial fertilizer, thus achieving rapid and long-term supply.

[0033] S6: Add 5 kg of compound bacterial fertilizer, 1 kg of humic acid, 0.5 kg of urea, and 0.3 kg of potassium sulfate into a blender and mix evenly to obtain a phosphorus-solubilizing biological bacterial fertilizer.

[0034] Example 2: A preparation method of a phosphorus-solubilizing biological bacterial fertilizer, which is prepared by the following steps: S1: Inoculate Bacillus aryabhattai in NB medium and activate and culture it in a constant temperature shaker at 170 r / min and 29 °C for 13 h to obtain an activated bacterial liquid; inoculate 1.5 mL of the activated bacterial liquid in 50 mL of NB medium and activate and culture it in a constant temperature shaker at 180 r / min and 29 °C for 25 h, centrifuge at 5500 r / min for 11 min, discard the supernatant, resuspend the bacterial cells with sterile water, and adjust the OD600 value to 1.0 to obtain a microbial inoculant.

[0035] S2: Add 3.5 kg of sodium alginate and 4.5 L of deionized water into a reaction kettle, stir at 23 °C and 550 r / min for 13 min, then add 1.2 kg of the microbial inoculant, continue to stir for 40 min to obtain a mixed solution. Drop the mixed solution into 3.4 L of a calcium chloride solution with a mass fraction of 4%, continue to stir for 1.2 h, filter, wash the filter cake with deionized water and absolute ethanol twice respectively, and vacuum dry at 70 °C for 1.2 h to obtain a slow-release bacterial fertilizer.

[0036] S3: Add 5.6 kg of chitosan powder and 7.5 L of acetic acid solution with a mass fraction of 4.5% into the reaction kettle, stir for 1.2 h under the conditions of 23 °C and 550 r / min, add 1.2 L of formaldehyde solution with a mass fraction of 4.5%, continue to stir for 13 min, let it stand for 35 min after stirring, heat up to 85 °C for aging at a rate of 11 °C / h, keep the temperature for 25 h, filter, wash the filter cake with deionized water and absolute ethanol twice respectively, and dry it in vacuum at 70 °C for 1.5 h to obtain the precursor powder; Transfer 4.2 kg of the precursor powder and 3.2 kg of epoxy resin powder to the muffle furnace, heat it to 950 °C under a nitrogen atmosphere, keep the temperature for 2.2 h, and cool it naturally to obtain the porous hard biochar powder.

[0037] S4: Add 3.4 kg of thiosalicylic acid and 5.6 L of deionized water into the reaction kettle, stir for 13 min under the conditions of 23 °C and 550 r / min, then add 4.5 kg of 1-aminobutylphosphonic acid, continue to stir for 1.2 h, then add 250 mL of sulfuric acid solution with a mass fraction of 23% to adjust the pH value to 3, heat up to 75 °C, dropwise add 4.5 L of formaldehyde solution with a mass fraction of 38%, continue to react for 4.5 h, carry out vacuum filtration under reduced pressure, wash the filter cake with deionized water and absolute ethanol twice respectively, and dry it in vacuum at 70 °C for 1.2 h to obtain phosphorylated modified thiosalicylic acid.

[0038] S5: Add 3 kg of phosphorylated modified thiosalicylic acid, 2.3 L of methanol and 4.5 L of dimethylformamide into the reaction kettle, stir for 40 min under the conditions of 55 °C and 550 r / min, then add 550 mL of ammonia water solution with a mass fraction of 13%, 1.2 kg of ferric chloride hexahydrate and 3.4 kg of porous hard biochar powder, continue to stir and react for 1.2 h, then add 2.3 kg of slow-release bacterial fertilizer, continue to stir and react for 1.2 h, filter, wash the filter cake with deionized water and absolute ethanol twice respectively, and dry it in vacuum at 70 °C for 1.2 h to obtain the compound bacterial fertilizer.

[0039] S6: Add 5.5 kg of the compound bacterial fertilizer, 1.2 kg of humic acid, 0.7 kg of urea and 0.35 kg of potassium sulfate into the blender and mix evenly to obtain a phosphorus-dissolving biological bacterial fertilizer.

[0040] Example 3: A preparation method of a phosphorus-dissolving biological bacterial fertilizer is prepared through the following steps: S1: Inoculate Bacillus aryabhattai in NB medium, activate and culture it in a constant temperature shaker at 200 r / min and 30 °C for 14 h to obtain the activated bacterial liquid; Inoculate 2 mL of the activated bacterial liquid in 50 mL of NB medium, activate and culture it in a constant temperature shaker at 200 r / min and 30 °C for 26 h, centrifuge at 6000 r / min for 12 min, discard the supernatant, resuspend the thalli with sterile water and adjust the OD600 value to 1.0 to obtain the microbial inoculant.

[0041] S2: Add 4 kg of sodium alginate and 5 L of deionized water into a reaction kettle, stir for 15 min under the conditions of 25 °C and 600 r / min, then add 2 kg of microbial inoculum, continue to stir for 60 min to obtain a mixed solution. Drop the mixed solution into 4 L of calcium chloride solution with a mass fraction of 5%, continue to stir for 2 h, filter, wash the filter cake with deionized water and absolute ethanol respectively for 3 times, and dry it in vacuum at 80 °C for 2 h to obtain a slow-release bacterial fertilizer.

[0042] S3: Add 6 kg of chitosan powder and 8 L of acetic acid solution with a mass fraction of 5% into a reaction kettle, stir for 2 h under the conditions of 25 °C and 600 r / min, add 2 L of formaldehyde solution with a mass fraction of 5%, continue to stir for 15 min, let it stand for 40 min after stirring, heat it to 90 °C for aging at a rate of 12 °C / h, keep the temperature for 26 h, filter, wash the filter cake with deionized water and absolute ethanol respectively for 3 times, and dry it in vacuum at 80 °C for 2 h to obtain a precursor powder; Transfer 5 kg of the precursor powder and 3.5 kg of epoxy resin powder to a muffle furnace, heat it to 1000 °C under a nitrogen atmosphere, keep the temperature for 3 h, and cool it naturally to obtain a porous hard biochar powder.

[0043] S4: Add 4 kg of thiosalicylic acid and 6 L of deionized water into a reaction kettle, stir for 15 min under the conditions of 25 °C and 600 r / min, then add 5 kg of 1-aminobutylphosphonic acid, continue to stir for 2 h, then add 300 mL of sulfuric acid solution with a mass fraction of 25% to adjust the pH value to 3, heat it to 78 °C, dropwise add 5 L of formaldehyde solution with a mass fraction of 40%, continue to react for 5 h, carry out vacuum filtration, wash the filter cake with deionized water and absolute ethanol respectively for 3 times, and dry it in vacuum at 80 °C for 2 h to obtain phosphorylated modified thiosalicylic acid.

[0044] S5: Add 3.2 kg of phosphorylated modified thiosalicylic acid, 3 L of methanol and 5 L of dimethylformamide into a reaction kettle, stir for 45 min under the conditions of 60 °C and 600 r / min, then add 600 mL of ammonia water solution with a mass fraction of 15%, 2 kg of ferric chloride hexahydrate and 4 kg of porous hard biochar powder, continue to stir and react for 2 h, then add 3 kg of slow-release bacterial fertilizer, continue to stir and react for 2 h, filter, wash the filter cake with deionized water and absolute ethanol respectively for 3 times, and dry it in vacuum at 80 °C for 2 h to obtain a composite bacterial fertilizer.

[0045] S6: Add 6 kg of composite bacterial fertilizer, 2 kg of humic acid, 1 kg of urea and 0.4 kg of potassium sulfate into a blender and mix evenly to obtain a phosphorus-solubilizing bio-bacterial fertilizer.

[0046] Comparative Example 1: On the basis of Example 3, the slow-release bacterial fertilizer in step S5 was replaced with the microbial inoculum in step S1, and the remaining steps remained unchanged to prepare a phosphorus-solubilizing bio-fertilizer.

[0047] Comparative Example 2: On the basis of Example 3, the porous hard biochar powder in step S5 was replaced with commercially available biochar powder of the same mass, and the remaining steps remained unchanged to prepare a phosphorus-solubilizing bio-fertilizer.

[0048] Comparative Example 3: On the basis of Example 3, without performing the treatment in step S4, the porous hard biochar powder and the slow-release bacterial fertilizer were directly mixed evenly according to a mass ratio of 4:3 to prepare a phosphorus-solubilizing bio-fertilizer.

[0049] In the examples and comparative examples: Bacillus aryabhattai WSX07P, with the biological deposit number: CGMCC No. 24486, the deposit date: March 9, 2022, the deposit unit: China General Microbiological Culture Collection Center, the deposit address: Institute of Microbiology, Chinese Academy of Sciences, No. 1, Beichen West Road, Chaoyang District, Beijing.

[0050] The phosphorus-solubilizing bio-fertilizers prepared in Examples 1 - 3 and Comparative Examples 1 - 3 were applied to corn seedlings, and the growth conditions of the above-ground and underground parts of the corn seedlings and the soil nutrient content were observed. The results are shown in Tables 1, 2, and 3: Put the corn seeds into a sterilized bottle, soak them with 75 - 80% (mass fraction) alcohol for 5 - 6 min, pour out the alcohol, add 3 - 4% sodium hypochlorite solution for surface sterilization for 2 - 3 min, pour out the sodium hypochlorite, wash with sterile water 6 - 8 times, and apply the phosphorus-solubilizing bio-fertilizer at a rate of 25 - 40 kg / hm 2 into the soil at a depth of 5 - 10 cm, plow and stir 3 - 4 times, plant the corn seeds at a rate of 6 - 8 seeds per square meter, and sprinkle water to make the soil water content at a depth of 5 - 10 cm reach 20 - 30%.

[0051] Harvest the corn at the 70th day of corn growth, conduct the determination of corn plant growth indicators and rhizosphere soil sampling. Dig out the corn plants with roots and soil, gently shake the roots by hand, air-dry the soil samples naturally and sieve them for the determination of soil physical and chemical properties; after sampling the corn seedlings, wash them with clean water, blot the surface moisture with filter paper, and divide them into above-ground and underground parts. For the above-ground part, measure the plant height and stem diameter of the corn. The above-ground part of the corn plant was blanched at 105 °C for 30 min and dried to a constant weight at 65 °C to measure the above-ground dry weight; for the underground part, use a root scanner (REGENT INSTRUMENTS LA2400) to record the total root length, total root surface area, root diameter, root volume, and number of root tips. The determination method for the available nutrient content of nitrogen, phosphorus, and potassium in the rhizosphere soil: Alkaline hydrolyzable nitrogen was determined by the alkaline diffusion method, and available phosphorus was determined by NaHCO3 For the determination of available potassium, the ammonium acetate extraction-flame spectrophotometry was used after extraction with the leaching-molybdenum antimony anti-colorimetry method. For the determination of soil phosphorus fractionation, the improved Hedley phosphorus fractionation extraction was adopted. Another soil sample was air-dried naturally and sieved for soil physical and chemical tests.

[0052] Table 1 Results of the growth of above-ground parts of maize seedlings Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Average plant height (cm) 58.73 59.36 60.38 50.12 52.85 50.32 Average stem diameter (mm) 11.28 12.78 13.38 7.11 9.25 7.23 Average aboveground dry weight (g / plant) 2.49 2.58 2.68 2.01 2.18 2.03 Table 2 Results of the root system of maize seedlings in the underground part Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Average total root length (cm) 384.81 390.21 398.01 352.35 375.25 356.25 Average total surface area (cm2) 19.71 20.21 21.53 17.21 18.25 17.35 Average diameter (mm) 0.66 0.69 0.72 0.50 0.58 0.51 Average root volume (cm3) 3.44 3.51 3.59 3.19 3.35 3.22 Average number of root tips 4137.48 4182.28 4221.01 3745.29 3892.42 3750.36 Table 3 Results of the available nutrient content in the rhizosphere soil of maize seedlings Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Alkaline hydrolyzable nitrogen (mg / kg) 97.89 98.23 98.86 91.22 93.58 91.56 Available phosphorus (mg / kg) 29.59 29.89 30.25 23.23 25.63 23.58 Available potassium (mg / kg) 175.88 176.25 177.21 160.25 168.21 161.15 As can be seen from Table 1 and Table 2, the phosphorus-solubilizing bio-fertilizer prepared in Examples 1-3 of the present invention has a significant promoting effect on the growth of the above-ground parts of maize seedlings, the growth of the root system, and the contents of available nutrients nitrogen, phosphorus, and potassium in the rhizosphere soil, indicating that the phosphorus-solubilizing bio-fertilizer prepared by the present invention can promote the growth of maize seedlings, promote the absorption of nutrients, and increase the content of available nutrients in the soil.

[0053] In Comparative Example 1, the slow-release bio-fertilizer was replaced with a microbial inoculant, and the microbial inoculant was encapsulated by the microcapsule effect of sodium alginate to achieve the purpose of slow release. Without the protection of sodium alginate, when applied to the soil, the organic acids secreted by the phosphorus-solubilizing bacteria were quickly chelated and inactivated by soil calcium ions and iron ions, so that the microbial inoculant could not fully play the role of phosphorus solubilization, affecting crop growth. In Comparative Example 2, the porous hard biochar powder was replaced with a commercially available biochar powder of the same mass. The porous hard biochar was pyrolyzed at high temperature with chitosan in dilute acetic acid solution and epoxy resin as an auxiliary carbon source to generate a rigid carbon skeleton, which was carbonized together with the precursor. The porous hard biochar powder has a higher specific surface area, higher porosity, and better roughness compared with the commercially available biochar, and can serve as an attachment site for the microbial inoculant, thus affecting the phosphorus-solubilizing effect of the microbial inoculant.

[0054] In Comparative Example 3, the porous hard biochar powder and the slow-release bio-fertilizer were directly mixed evenly. The carboxyl group in the thiosalicylic acid structural formula in the metal skeleton can bind to the hydroxyl group on the sodium alginate shell wrapped on the surface of the slow-release bio-fertilizer. The metal skeleton serves as a bridge to fix the slow-release bio-fertilizer on the surface of the porous hard biochar powder. When applied to the soil, the organic acids released by the phosphorus-solubilizing bacteria will activate the metal skeleton serving as a bridge. The thiosalicylic acid in the metal skeleton structure is pH-responsive. After contacting the organic acids, the structure collapses, releasing the phosphate groups grafted in the structure to actively supply phosphorus elements to the plant roots. And the collapse of the metal skeleton structure will prompt the connected slow-release bio-fertilizer to be quickly released, so as to achieve rapid and long-term supply.

[0055] It should be noted that in this text, terms such as "including", "comprising", or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such a process, method, article, or device.

[0056] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention.

Claims

1. A phosphate-dissolving biological fertilizer, characterized in that: The components include the following by mass: 50-60 parts of compound bacterial fertilizer, 10-20 parts of humic acid, 5-10 parts of urea and 3-4 parts of potassium sulfate; The composite bacterial fertilizer is prepared by the following steps: Add phosphorylated thiosalicylic acid, methanol and dimethylformamide into a reactor, stir at 50-60°C and 500-600r / min for 30-45min, then add 10-15wt% ammonia solution, ferric chloride hexahydrate and porous hard biochar powder, stir and react for 1-2h, then add slow-release bacterial fertilizer, stir and react for 1-2h, filter, wash and vacuum dry to obtain a composite bacterial fertilizer.

2. A phosphate-dissolving biological fertilizer according to claim 1, characterized in that: The dosage ratio of the phosphorylated modified thiosalicylic acid, methanol, dimethylformamide, ammonia solution, ferric chloride hexahydrate, porous hard biochar powder and slow-release bacterial fertilizer is 2.8-3.2kg: 2-3L: 4-5L: 500-600mL: 1-2kg: 3-4kg: 2-3kg.

3. A phosphate-dissolving biological fertilizer according to claim 1, characterized in that: The porous hard biochar powder is prepared by the following steps: Add chitosan powder and 4-5wt% acetic acid solution into a reactor, stir at 20-25℃ and 500-600r / min for 1-2h, add 4-5wt% formaldehyde solution, continue stirring for 10-15min, stand for 30-40min after stirring, heat to 80-90℃ at a rate of 10-12℃ / h, keep warm for 24-26h, filter, wash, and vacuum dry to obtain precursor powder; transfer the precursor powder and epoxy resin powder to a muffle furnace at a mass ratio of 4-5:3-3.5, heat to 900-1000℃ under a nitrogen atmosphere, keep warm for 2-3h, and cool naturally to obtain porous hard biochar powder; The usage ratio of the chitosan powder, the acetic acid solution and the formaldehyde solution is 5-6kg:7-8L:1-2L.

4. The phosphate-dissolving biological fertilizer according to claim 1, characterized in that: The phosphorylated modified thiosalicylic acid is prepared by the following steps: Add thiosalicylic acid and deionized water into a reaction kettle, stir at 20-25°C and 500-600r / min for 10-15min, then add 1-aminobutylphosphoric acid, continue stirring for 1-2h, then add 20-25wt% sulfuric acid solution to adjust the pH value to 3-4, heat to 70-78°C, add 37-40wt% formaldehyde solution dropwise, continue reacting for 4-5h, reduce pressure and filter, wash, and vacuum dry to obtain phosphorylated thiosalicylic acid.

5. A phosphate-dissolving biological fertilizer according to claim 4, characterized in that: The dosage ratio of the thiosalicylic acid, deionized water, 1-aminobutylphosphoric acid, sulfuric acid solution and formaldehyde solution is 3-4kg:5-6L:4-5kg:200-300mL:4-5L.

6. The phosphate-dissolving biological fertilizer according to claim 1, characterized in that: The slow-release bacterial fertilizer is prepared by the following steps: Add sodium alginate and deionized water into the reactor, stir at 20-25℃ and 500-600r / min for 10-15min, then add microbial agent, continue stirring for 30-60min, drop into 3-5wt% calcium chloride solution, continue stirring for 1-2h, filter, wash, and vacuum dry to obtain slow-release bacterial fertilizer.

7. The phosphate-dissolving biological fertilizer according to claim 6, characterized in that: The dosage ratio of the sodium alginate, deionized water, microbial agent and calcium chloride solution is 3-4kg:4-5L:1-2kg:3-4L.

8. The phosphate-dissolving biological fertilizer according to claim 6, characterized in that: The microbial agent is prepared by the following steps: The Bacillus agglomerans was inoculated into NB culture medium, and activated and cultured in a constant temperature shaker at 150-200 r / min and 28-30° C. for 12-14 hours to obtain an activated bacterial solution; 1-2 mL of the activated bacterial solution was inoculated into 50 mL of NB culture medium, and activated and cultured in a constant temperature shaker at 150-200 r / min and 28-30° C. for 24-26 hours, and centrifuged at 5000-6000 r / min for 10-12 minutes, the supernatant was discarded, the bacteria were resuspended with sterile water, and the OD600 value was adjusted to 1.0 to obtain a microbial agent.

9. The method for preparing a phosphate-dissolving biological fertilizer according to claim 1, characterized in that: The steps include: The compound bacterial fertilizer, humic acid, urea and potassium sulfate are added into a blender and mixed evenly to obtain a phosphorus-dissolving biological bacterial fertilizer.

10. Use of the phosphate-dissolving biological fertilizer according to claim 1 to promote the growth of corn seedlings.