Drought and saline-alkali resistant microbial fertilizer, preparation method and application thereof

Abstract

The application discloses a kind of drought-resistant saline-alkali microbial fertilizer, including composite microbial inoculant, modified humic acid, element auxiliary agent, biochar and organic material;The composite microbial inoculant includes bacillus subtilis, halophilic salt bacillus and lipogenic azotobacter;The modified humic acid is prepared by dimethyl vinylphosphonate, acrylic acid, silane monomer and humic acid polymerization.The application will composite microbial inoculant and modified humic acid as functional component and be supplemented with element auxiliary agent, biochar and organic material as matrix component, can be improved by microbial regulation, soil structure improvement and alkali-induced domestication etc. The adaptability of crop in saline-alkali soil, drought resistance and nutrient absorption capacity, in turn, improve land utilization and production effect, can be widely applied in composite microbial fertilizer technical field.

Description

Technical Field

[0001] This invention relates to the field of compound microbial fertilizer technology, specifically to a drought-resistant and salt-alkali-resistant microbial fertilizer, its preparation method, and its application. Background Technology

[0002] It is reported that nearly 10% of the world's landmass is covered by different types of saline-alkali soil, mainly distributed in arid and semi-arid regions. Half of the existing irrigated land is threatened by secondary salinization. Different types of saline-alkali land are distributed in Northeast, North, and Northwest China. In addition, various types of coastal saline soils (such as coastal mudflats) are widely distributed along the coast. These types of soil lack proper conditioning and are of poor quality.

[0003] Saline-alkali soils are characterized by the presence of sodium carbonate and sodium bicarbonate in their soil solution, and exchangeable sodium in their soil colloids. Therefore, saline-alkali soils are highly alkaline, with a pH exceeding 9. The high concentration of the soil solution in saline-alkali soils exceeds that of crop cells, causing them to lose water and impairing their function. Furthermore, saline-alkali soils are prone to compaction, which prevents gas from being trapped within the soil, resulting in heavy, sticky soil with poor permeability. This reduces crop respiration efficiency. Combined, these factors severely impact crop cell metabolism, leading to insufficient energy and absorption capacity. Consequently, crops also lack inorganic salts, significantly hindering their growth. Saline-alkali soils often result in poor harvests, sometimes even leading to total crop failure. Therefore, saline-alkali soils have become a low-yield soil type in agricultural production, severely impacting agricultural development.

[0004] In response to the characteristics of saline-alkali soils, existing technologies often use microbial fertilizers to improve them, enabling crops to be grown normally in saline-alkali soils and improving land utilization. Microbial fertilizers refer to "live microbial products composed of specific microorganisms and nutrients, which can provide, maintain, or improve plant nutrition, increase agricultural product yield, or improve the quality of agricultural products."

[0005] The development and application of microbial fertilizers are particularly important for the sustainable development of Chinese agriculture. They play a vital role in improving and maintaining soil fertility, transforming nutrients, increasing fertilizer utilization, promoting crop growth, antagonizing soil-borne diseases, and purifying the environment and balancing the ecosystem. However, saline-alkali soils often suffer from severe drought in addition to high salinity, and existing microbial fertilizer technologies cannot effectively improve the nutrient absorption capacity of crops in saline-alkali soils.

[0006] Therefore, there is an urgent need for a drought- and salt-tolerant microbial fertilizer that can effectively improve crops' adaptability, drought resistance, and nutrient absorption capacity in saline-alkali soils. Summary of the Invention

[0007] Purpose of the invention: In view of the deficiencies of the prior art, the purpose of this invention is to provide a drought-resistant and salt-alkali-resistant microbial fertilizer, its preparation method and application, which can effectively improve the crop's adaptability, drought resistance and nutrient absorption capacity in saline-alkali soil.

[0008] Technical solution:

[0009] This invention provides a drought- and salt-tolerant microbial fertilizer, comprising a compound microbial agent, modified humic acid, elemental additives, biochar, and organic materials;

[0010] The compound microbial agent includes Bacillus subtilis, halophilic Bacillus, and lipophilic nitrogen-fixing spirochetes.

[0011] The modified humic acid is prepared by polymerization of dimethyl vinylphosphonate, acrylic acid, silane monomer and humic acid;

[0012] The silane monomer has the structure shown in Formula A:

[0013] .

[0014] Furthermore, the silamine monomer is prepared by the following steps:

[0015] (1) In the reactor, add bromobutyltrimethoxysilane and organic solvent, stir, then add acrylamide, alkaline catalyst and polymerization inhibitor, and heat to 60-80℃ for 4-6 hours;

[0016] (2) After the reaction is completed, the silane monomer is obtained by cooling, filtering, washing and drying.

[0017] Furthermore, the molar ratio of bromobutyltrimethoxysilane to acrylamide is 1.2-1.3:1;

[0018] The organic solvent is selected from N,N-dimethylformamide, dimethyl sulfoxide, or acetonitrile;

[0019] The alkaline catalyst is selected from sodium hydroxide, potassium hydroxide, or potassium carbonate.

[0020] The polymerization inhibitor is selected from one of hydroquinone monomethyl ether, tert-butylcatechol, or 2,6-di-tert-butyl-p-cresol.

[0021] Furthermore, the modified humic acid is prepared through the following steps:

[0022] (1) In the reactor, add acrylic acid, dimethyl vinylphosphonate, silicone monomer and deionized water, stir and heat to 50-60℃, then add humic acid and base catalyst, and react for 4-6 hours under nitrogen protection.

[0023] (2) After the reaction is completed, the modified humic acid is obtained by filtration, drying and pulverizing.

[0024] The modified humic acid of this invention contains acrylic acid monomers, which can further improve the pH value of saline-alkali soils. Dimethyl vinylphosphonate and silamine monomers can not only provide trace elements such as phosphorus, silicon, and nitrogen, but also the phosphate structure of dimethyl vinylphosphonate can compete with sodium ions in the soil for adsorption sites, reducing the impact of crop accumulation in saline-alkali soils. The silamine monomers can cross-link to form a network structure, enhancing the water retention capacity of the local soil and the mechanical strength of crop cell walls, thereby enhancing the drought resistance and salt tolerance of crops.

[0025] Further, in step (1), the mass ratio of acrylic acid, dimethyl vinylphosphonate, silicone monomer and humic acid is (15-20):(8-12):(5-8):(35-50).

[0026] The alkaline catalyst is selected from sodium hydroxide, potassium hydroxide, or potassium carbonate.

[0027] The modified humic acid has an average particle size of 1-20 μm.

[0028] Furthermore, the elemental additive is selected from at least one of urea, monoammonium phosphate, potassium sulfate, and potassium chloride; the organic material is selected from at least one of wheat straw, corn straw, and shiitake mushroom residue.

[0029] Furthermore, the number of effective viable bacteria in the drought-resistant and salt-alkali-resistant microbial fertilizer is not less than 6 × 10⁻⁶. 8 CFU / g;

[0030] The effective viable count ratio of Bacillus subtilis, Bacillus halophilicus, and Azotobacter lipophilicus in the compound microbial agent is (3-5):(1.5-2.5):(1-1.5).

[0031] This invention uses a mixture of Bacillus subtilis, Bacillus halophilus, and Azotobacter lipophilus as a compound microbial agent. This agent can effectively improve the local environment of crops in saline-alkali soil and increase nutrient content. On the one hand, Bacillus subtilis can secrete acidic substances, acidifying the local environment and promoting mineral release, thus improving the environment of saline-alkali soil. On the other hand, Bacillus halophilus can effectively decompose organic matter in saline-alkali soil, improving the absorption of micronutrients by crops. Finally, Azotobacter lipophilus can not only effectively fix nitrogen and improve crop growth, but also secrete extracellular polysaccharides, improving soil aggregate structure and reducing salt osmotic pressure.

[0032] Furthermore, based on a total mass fraction of 100%, the mass percentage of each component in the drought-resistant and salt-alkali-resistant microbial fertilizer is as follows:

[0033] Compound microbial inoculant 5-8%

[0034] Modified humic acid 10-15%

[0035] Elemental additives 20-25%

[0036] Biochar 10-15%

[0037] The remainder is organic material.

[0038] The drought-resistant and salt-alkali-resistant microbial fertilizer of the present invention not only provides the macronutrients such as nitrogen, phosphorus, and potassium required by crops by adding element adjuvants, but also improves the structure of saline-alkali soil, enriches nutrients and improves water and fertilizer retention capacity by biochar and organic materials, thereby effectively improving the adaptability of crops in saline-alkali soil.

[0039] Another aspect of the present invention provides a method for preparing any one of the above-mentioned drought-resistant and salt-alkali-resistant microbial fertilizers, comprising the following steps:

[0040] (1) After crushing the elemental additives and organic materials, mix them evenly with biochar and modified humic acid in proportion to obtain a mixture.

[0041] (2) The mixture from step (1) is granulated, dried and then sprayed with a compound microbial agent to obtain the drought-resistant and salt-alkali-resistant microbial fertilizer.

[0042] Finally, the present invention also provides the application of any of the above-mentioned drought-resistant and salt-alkali-resistant microbial fertilizers in saline-alkali soils.

[0043] Beneficial effects:

[0044] (1) The drought-resistant and salt-alkali-resistant microbial fertilizer provided by the present invention uses compound microbial agents and modified humic acid as functional components and supplements them with elemental adjuvants, biochar and organic materials as matrix components. It can improve the crop's adaptability, drought resistance and nutrient absorption capacity in saline-alkali soil through microbial regulation, soil structure improvement and alkali-induced domestication, thereby improving land utilization and production effect. It can be widely used in the field of compound microbial fertilizer technology.

[0045] (2) The drought-resistant and salt-alkali-resistant microbial fertilizer provided by the present invention, by mixing Bacillus subtilis, halophilic Bacillus and lipophilic azospirobacter as a compound microbial agent, can effectively improve the local environment of crops in saline-alkali soil and increase nutrient content. On the one hand, Bacillus subtilis can secrete acidic substances, acidify the local environment and promote the release of minerals, thus improving the environment of saline-alkali soil. On the other hand, halophilic Bacillus can effectively decompose organic matter in saline-alkali soil and improve the absorption of micronutrients by crops. Finally, lipophilic azospirobacter can not only effectively fix nitrogen and improve the growth of crops, but also secrete extracellular polysaccharides, improve soil aggregate structure and reduce salt osmotic pressure.

[0046] (3) The drought-resistant and salt-alkali-resistant microbial fertilizer provided by the present invention uses modified humic acid as a functional component. Based on the natural organic macromolecular structure of humic acid containing a large number of active functional groups such as carboxyl and hydroxyl groups, it can not only improve the pH value of saline-alkali soil and enhance the salt and alkali resistance of bacteria, but also further improve its functionality by polymerizing its active functional groups with other monomers.

[0047] (4) The modified humic acid in the drought-resistant and salt-alkali-resistant microbial fertilizer provided by the present invention is prepared by polymerizing humic acid with dimethyl vinylphosphonate, acrylic acid and silane monomer. The acrylic acid monomer can further improve the ability of humic acid to improve the pH value of saline-alkali soil. Dimethyl vinylphosphonate and silane monomer can not only provide phosphorus, silicon and nitrogen trace elements, but also the phosphate structure of dimethyl vinylphosphonate can compete with sodium ions in the soil for adsorption sites, reducing the impact of crops in saline-alkali soil. The silane monomer can cross-link with each other to form a network structure, enhance the water retention capacity of local soil and the mechanical strength of crop cell walls, thereby enhancing the drought resistance and salt-alkali tolerance of crops.

[0048] (5) The drought-resistant and salt-alkali-resistant microbial fertilizer provided by the present invention can improve the salt-alkali resistance of crops, thereby enabling them to increase the salt content in the crop through alkali-induced domestication under high salt-alkali concentration conditions, reduce the occurrence of transpiration, and regulate the root system to grow downward, thereby improving the drought resistance and nutrient absorption capacity of crops.

[0049] (6) The drought-resistant and salt-alkali-resistant microbial fertilizer provided by the present invention not only provides the macronutrients such as nitrogen, phosphorus and potassium required by crops by adding element adjuvants, but also improves the structure of saline-alkali soil, enriches nutrients and improves water and fertilizer retention capacity by biochar and organic materials, thereby effectively improving the adaptability of crops in saline-alkali soil. Detailed Implementation

[0050] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0051] The *Bacillus subtilis* strain used in this invention was purchased from the China General Microbiological Culture Collection Center (CGMCC), with a deposit date of November 20, 2017, and accession number CGMCC14929; the *Halobacillus halophilus* strain was purchased from the CGMCC, with a deposit date of June 1, 2003, and accession number CGMCC1.3407, the original strain of which originated from the German Microbiological Collection Center (DSMZ), with original accession number DSM 2266; and the *Azospirillum lipoferum* strain was purchased from the CGMCC, with a deposit date of January 20, 2016, and accession number CGMCC. 12060; The commercially available microbial fertilizer is a microbial organic fertilizer purchased from Henan Jiufeng Water Treatment Co., Ltd.; the remaining reagents and equipment are conventional reagents and equipment in this technical field.

[0052] Preparation of silamine monomers

[0053] The silane monomer is prepared by the following steps:

[0054] (1) In a reactor, add 0.06 mol of bromobutyltrimethoxysilane and 100 mL of N,N-dimethylformamide, stir, add 0.05 mol of acrylamide, 0.1 g of potassium hydroxide and 0.3 g of hydroquinone monomethyl ether, and heat to 70 °C and react for 4 hours.

[0055] (2) After the reaction is complete, the silane monomer is obtained by cooling, filtering, washing and drying.

[0056] Mass spectrometry data of silane monomers: The products were analyzed by LC-MS, and the m / z values ​​of the products were 247.12 (100.0%), 248.17 (17.3%), and 249.12 (4.8%).

[0057] Preparation of modified humic acid-1

[0058] Modified humic acid-1 was prepared by the following steps:

[0059] (1) In a reactor, add 2g acrylic acid, 1g dimethyl vinylphosphonate, 0.5g silane monomer and 100mL deionized water, stir and heat to 55℃, then add 5g humic acid and 0.2g potassium hydroxide, and react for 6 hours under nitrogen protection.

[0060] (2) After the reaction is completed, the modified humic acid-1 is obtained by filtering, drying and crushing to an average particle size of 5 μm.

[0061] Preparation of modified humic acid-2

[0062] The preparation is basically the same as that of modified humic acid-1, except that in step (1), 2g acrylic acid, 1g dimethyl vinylphosphonate and 0.5g silane monomer are replaced with 2.5g acrylic acid and 1g acrylamide.

[0063] Example 1

[0064] The following steps are used to prepare drought- and salt-tolerant microbial fertilizer:

[0065] (1) After crushing urea and wheat straw, mix them evenly with biochar and modified humic acid-1 in a certain proportion to obtain a mixture.

[0066] (2) The mixture from step (1) is granulated, dried and then sprayed with a compound microbial agent to obtain the drought-resistant and salt-alkali-resistant microbial fertilizer.

[0067] The effective viable bacteria count in the drought-resistant and salt-alkali-resistant microbial fertilizer is 9 × 10⁻⁶. 8 CFU / g;

[0068] The effective viable count ratio of Bacillus subtilis, Bacillus halophilicus, and Azotobacter lipophilicus in the compound microbial agent is 5:2:1.

[0069] Based on a total mass fraction of 100%, the mass percentage of each component in the drought-resistant and salt-alkali-resistant microbial fertilizer is as follows:

[0070] 8% compound microbial inoculant

[0071] Modified humic acid-1 12%

[0072] 25% urea

[0073] 15% biochar

[0074] The remainder is wheat straw.

[0075] Example 2

[0076] The process is basically the same as in Example 1, except that the effective viable count ratio of Bacillus subtilis, halophilic Bacillus, and lipophilic azotoxin in the compound microbial agent is 3:2:1.

[0077] Based on a total mass fraction of 100%, the components and their mass percentages in the drought-resistant and salt-alkali-resistant microbial fertilizer are revised as follows:

[0078] 6% compound microbial agent

[0079] Modified humic acid-1 14%

[0080] Monoammonium phosphate 20%

[0081] 10% biochar

[0082] The remainder is corn stalks.

[0083] Example 3

[0084] Basically the same as Example 1, except that, based on a total mass fraction of 100%, the components and their mass percentages in the drought-resistant and salt-alkali-resistant microbial fertilizer are changed as follows:

[0085] 5% compound microbial agent

[0086] Modified humic acid-1 15%

[0087] Potassium chloride 25%

[0088] 10% biochar

[0089] The remainder is shiitake mushroom residue.

[0090] Comparative Example 1

[0091] Commercially available microbial fertilizers.

[0092] Comparative Example 2

[0093] The process is basically the same as in Example 1, except that the compound microbial agent is replaced with Bacillus subtilis containing an equal number of live bacteria.

[0094] Comparative Example 3

[0095] The process is basically the same as in Example 1, except that modified humic acid-1 is replaced with an equal amount of humic acid.

[0096] Comparative Example 4

[0097] The method is basically the same as in Example 1, except that modified humic acid-1 is replaced with an equal amount of modified humic acid-2.

[0098] Performance testing

[0099] A tomato planting experiment was conducted in saline-alkali land along the coast of Jiangsu Province: Tomato fields with an area of ​​1 mu (approximately 0.067 hectares) were selected. At the time of sowing, the experimental groups were treated with 80 kg / 667 m² of fertilizer. 2The products of Examples 1-3 and Comparative Examples 1-4 were used, while the control group did not receive any additives. The same cultivation and management practices were employed. Statistics were collected after the tomato harvest, and parallel experiments were conducted. Crop yield, total soil salinity, average soil pH, and soil water holding capacity were measured in different experimental fields.

[0100] The results are recorded in the table below:

[0101]

[0102] According to the comparison of the recorded results of Examples 1-3 with Comparative Example 1 and the control group, the drought-resistant and salt-alkali-resistant microbial fertilizer provided by the present invention, by using compound microbial agents and modified humic acid as functional components and supplementing them with elemental adjuvants, biochar and organic materials as matrix components, can effectively improve the crop's adaptability, drought resistance and nutrient absorption capacity in saline-alkali soil, thereby increasing crop yield. It can be widely used in the field of compound microbial fertilizer technology.

[0103] According to the comparison of the recorded results of Examples 1-3 and Comparative Example 2, the drought-resistant and salt-alkali-resistant microbial fertilizer provided by the present invention, by mixing Bacillus subtilis, halophilic Bacillus, and lipophilic nitrogen-fixing spirochetes as a compound microbial agent, can effectively improve the local environment of crops in saline-alkali soil and increase nutrient content, thereby effectively increasing crop yield and improving the soil environment.

[0104] According to the comparison of the recorded results of Examples 1-3 and Comparative Examples 3-4, the drought-resistant and salt-alkali-resistant microbial fertilizer provided by the present invention uses modified humic acid, which is obtained by polymerizing dimethyl vinyl phosphonate, acrylic acid and silane monomers with humic acid, as a functional component. It can significantly improve the environment of saline-alkali soil and enhance the water retention capacity of crops, thereby increasing crop yield.

[0105] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A drought- and salt-tolerant microbial fertilizer, characterized in that, It includes compound microbial agents, modified humic acid, elemental additives, biochar, and organic materials; The compound microbial agent includes Bacillus subtilis, halophilic Bacillus, and lipophilic nitrogen-fixing spirochetes. The modified humic acid is prepared by polymerization of dimethyl vinylphosphonate, acrylic acid, silane monomer and humic acid; The silane monomer has the structure shown in Formula A: ； The silamine monomer is prepared by the following steps: (1) In the reactor, add bromobutyltrimethoxysilane and organic solvent, stir, then add acrylamide, alkaline catalyst and polymerization inhibitor, and heat to 60-80℃ for 4-6 hours; (2) After the reaction is completed, the silane monomer is obtained by cooling, filtering, washing and drying.

2. The drought-resistant and salt-alkali-resistant microbial fertilizer according to claim 1, characterized in that, The molar ratio of bromobutyltrimethoxysilane to acrylamide is 1.2-1.3:1; The organic solvent is selected from N,N-dimethylformamide, dimethyl sulfoxide, or acetonitrile; The alkaline catalyst is selected from sodium hydroxide, potassium hydroxide, or potassium carbonate. The polymerization inhibitor is selected from one of hydroquinone monomethyl ether, tert-butylcatechol, or 2,6-di-tert-butyl-p-cresol.

3. The drought-resistant and salt-alkali-resistant microbial fertilizer according to claim 1, characterized in that, The modified humic acid is prepared through the following steps: (1) In the reactor, add acrylic acid, dimethyl vinylphosphonate, silicone monomer and deionized water, stir and heat to 50-60℃, then add humic acid and base catalyst, and react for 4-6 hours under nitrogen protection. (2) After the reaction is completed, the modified humic acid is obtained by filtration, drying and pulverizing.

4. The drought-resistant and salt-alkali-resistant microbial fertilizer according to claim 3, characterized in that, In step (1), the mass ratio of acrylic acid, dimethyl vinylphosphonate, silicone monomer and humic acid is (15-20):(8-12):(5-8):(35-50). The alkaline catalyst is selected from sodium hydroxide, potassium hydroxide, or potassium carbonate. The modified humic acid has an average particle size of 1-20 μm.

5. The drought-resistant and salt-alkali-resistant microbial fertilizer according to claim 1, characterized in that, The elemental additive is selected from at least one of urea, monoammonium phosphate, potassium sulfate, and potassium chloride; the organic material is selected from at least one of wheat straw, corn straw, and shiitake mushroom residue.

6. The drought-resistant and salt-alkali-resistant microbial fertilizer according to claim 1, characterized in that, The drought-resistant and salt-alkali-resistant microbial fertilizer contains no less than 6 × 10⁶ effective viable bacteria. 8 CFU / g; The effective viable count ratio of Bacillus subtilis, Bacillus halophilicus, and Azotobacter lipophilicus in the compound microbial agent is (3-5):(1.5-2.5):(1-1.5).

7. The drought-resistant and salt-alkali-resistant microbial fertilizer according to claim 1, characterized in that, Based on a total mass fraction of 100%, the mass percentage of each component in the drought-resistant and salt-alkali-resistant microbial fertilizer is as follows: Compound microbial inoculant 5-8% Modified humic acid 10-15% Elemental additives 20-25% Biochar 10-15% The remainder is organic material.

8. The method for preparing the drought-resistant and salt-alkali-resistant microbial fertilizer according to any one of claims 1-7, characterized in that, Includes the following steps: (1) After crushing the elemental additives and organic materials, mix them evenly with biochar and modified humic acid in proportion to obtain a mixture. (2) The mixture from step (1) is granulated, dried and then sprayed with a compound microbial agent to obtain the drought-resistant and salt-alkali-resistant microbial fertilizer.

9. The application of the drought-resistant and salt-alkali-resistant microbial fertilizer according to any one of claims 1-7 in saline-alkali soil.

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