Preparation method of salt-reducing compound bacterial fertilizer and application of salt-reducing compound bacterial fertilizer in agriculture

Abstract

The invention relates to a preparation method of a salt-reducing compound bacterial fertilizer and an application in agriculture, the preparation method of the salt-reducing compound bacterial fertilizer comprises the following steps: S1, respectively mixing diatomite and a compound strain liquid, adsorbing, and drying to obtain an intermediate product; s2, mixing and heating starch and sodium hydroxide, then adding polypropylene glycol diglycidyl ether, and continuously reacting to obtain modified starch; s3, mixing and heating the modified starch and starch, then adding the intermediate product and a cross-linking agent, and stirring for reaction to obtain the salt-reducing compound bacterial fertilizer. According to the invention, a plurality of strains are compatible, are respectively adsorbed by the diatomite, and are coated by the modified starch, so that the stability of the strains is enhanced, the possibility that different strains mutually inhibit growth is reduced, the functions of improving soil and promoting plant growth can be stably and efficiently exerted, and the application prospect is good.

Description

Technical Field

[0001] The present invention relates to the field of agricultural technologies, and particularly to a preparation method of a salt-reducing compound microbial fertilizer and its application in agriculture. Background Art

[0002] Although traditional chemical fertilizers can increase crop yields in the short term, long-term use can lead to soil compaction, loss of organic matter, damage to the microbial community, and reduction of soil fertility. At the same time, excessive nutrients are likely to cause eutrophication of water bodies or greenhouse gas emissions, and lead to a decline in the stress resistance of crops and a reduction in the quality of agricultural products, presenting problems of unsustainability and relatively large negative impacts.

[0003] In contrast, microbial fertilizers improve the soil structure through beneficial bacterial communities such as nitrogen-fixing bacteria and phosphorus-solubilizing bacteria, enhance water retention and air permeability, and improve nutrient utilization efficiency, which can greatly reduce the usage amount of chemical fertilizers. In addition, compound microbial fertilizers can secrete substances such as organic acids and polysaccharides through the synergistic action of bacterial communities to complex sodium ions in the soil and reduce the salt content. They can also synthesize specific amino acids, proteins and other substances to enhance the salt tolerance of plants, thereby reducing soil salinity through microbial metabolic activities, and having a good effect on improving the salinization and alkalization of cultivated land, meeting the trend of sustainable agricultural development. Therefore, microbial fertilizers have significant advantages in improving soil, enhancing crop quality and reducing environmental pollution, and are an important development direction of ecological agriculture.

[0004] Existing technologies such as CN112521231A - A soil-improving microbial fertilizer, CN116041106A - A biological microbial fertilizer, CN103011915A - A microbial fertilizer, etc. have all achieved the effects of improving soil structure, promoting crop growth, and enhancing the ability of plants to resist diseases and pests by compounding strains such as Bacillus subtilis and actinomycetes with nutrients.

[0005] However, in existing technologies, different microorganisms are directly co-mixed, and it is difficult to ensure the stability and activity of the strains. Moreover, antagonistic effects may be formed between the strains due to the growth and secretion of substances inhibiting each other's growth, or interfering with the growth of weak strains by competing for nutrient resources, which has an adverse impact on the activity of the strains, reduces the synergistic effect of the compound bacterial community, and it is difficult to obtain the ideal effects of improving soil and promoting crop growth, which urgently needs to be solved.

[0006] In summary, it is necessary to develop a new technical solution to overcome the defects existing in the prior art. Summary of the Invention

[0007] Based on this, the present invention provides a preparation method of a salt-reducing compound bacterial fertilizer and its application in agriculture. The present invention combines multiple strains of bacteria, adsorbs them with diatomaceous earth respectively, and then coats them with modified starch, which enhances the stability of the strains and reduces the possibility of mutual inhibition of growth among different strains. It can stably and efficiently play the functions of improving soil and promoting plant growth, and has good application prospects.

[0008] The object of the present invention is to provide a preparation method of a salt-reducing compound bacterial fertilizer, and the preparation method of the salt-reducing compound bacterial fertilizer includes the following steps:

[0009] S1. Mix diatomaceous earth and the compound bacterial strain solution respectively, and after adsorption and drying, obtain an intermediate product;

[0010] S2. Mix starch and sodium hydroxide and heat them, then add polypropylene glycol diglycidyl ether and continue the reaction to obtain modified starch;

[0011] S3. Mix the modified starch and starch and heat them, then add the intermediate product and a cross-linking agent, and obtain the salt-reducing compound bacterial fertilizer after stirring and reacting.

[0012] Furthermore, it also includes:

[0013] S4. Mix the salt-reducing compound bacterial fertilizer with nutrients.

[0014] Furthermore, in step S2, the heating temperature is 60 - 80 °C.

[0015] Furthermore, in step S2, the mass ratio of starch, sodium hydroxide, and polypropylene glycol diglycidyl ether is 10:(0.5 - 1):(5 - 15).

[0016] Furthermore, in step S3, the heating temperature is 60 - 80 °C.

[0017] Furthermore, in step S3, the mass ratio of the modified starch to starch is (0.5 - 1):1.

[0018] Furthermore, the compound bacterial strains include Bacillus subtilis, Bacillus megaterium, Streptomyces microflavus, and Azotobacter chroococcum.

[0019] Furthermore, the nutrients include urea, diammonium hydrogen phosphate, and potassium sulfate.

[0020] Furthermore, the cross-linking agent is sodium hexametaphosphate.

[0021] Furthermore, the mass ratio of the salt-reducing compound bacterial fertilizer, urea, diammonium hydrogen phosphate, and potassium sulfate is (2 - 4):(3 - 6):(4 - 8):(3 - 6).

[0022] Furthermore, the dosage ratio of Bacillus subtilis, Bacillus megaterium, Streptomyces microflavus, and Azotobacter chroococcum is (1 - 2):(1 - 1.5):(1 - 1.5):(0.1 - 0.5).

[0023] Another object of the present invention is to provide the application of the preparation method of the above-mentioned salt-reducing compound bacterial fertilizer in agriculture.

[0024] The present invention has the following beneficial effects:

[0025] The salt-reducing compound bacterial fertilizer provided by the present invention first uses diatomaceous earth to adsorb the composite bacterial strains respectively, and then coats them with modified starch to obtain the bacterial fertilizer product. Diatomaceous earth has a rich pore structure. After using it to adsorb bacterial strains for bacterial fertilizer, it not only helps the preservation, growth and reproduction of bacterial strains, but also can improve the soil structure, enhance the water permeability and fertilizer retention ability, and also helps to adsorb heavy metals, salts and other substances, neutralize pollutants in the soil, and has multiple functions.

[0026] The modified starch of the present invention is: under the catalysis of alkali, the hydroxyl group of starch first generates an oxygen anion, and then further reacts with an epoxy group to introduce a polypropylene glycol group into the modified starch. The modified starch not only forms a cross-linked structure through polypropylene glycol diglycidyl ether, improving the coating and film-forming ability, but also the hydrophobic propoxy chain segment enhances the stability of the modified starch, enabling the bacterial strains adsorbed by diatomaceous earth in the core to be kept stable for a long time, realizing gentle and continuous growth, and also prolonging the effective time of the bacterial fertilizer; moreover, after coating the diatomaceous earth adsorbed with bacterial strains in the present invention, the growth inhibition and antagonistic effects between different bacterial strains are reduced, ensuring that the composite bacterial strains can play a synergistic role persistently and stably, jointly realizing the salt-reducing function, and at the same time promoting the growth of crops efficiently. Detailed Embodiments

[0027] In order to more clearly illustrate the technical solutions of the present invention, the following examples are listed. The raw materials, reactions, and post-treatment means appearing in the examples are all common raw materials on the market and technical means well-known to those skilled in the art, unless otherwise specified.

[0028] The terms "preferred", "preferably", "more preferably", etc. in the present invention refer to the embodiments of the present invention that can provide certain beneficial effects in certain cases. However, in the same or other cases, other embodiments may also be preferred. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present invention.

[0029] It should be understood that, except in any operating instance or otherwise indicated, all numbers representing amounts of ingredients or the like used in the specification and claims should be understood to be modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that vary depending upon the desired properties sought to be obtained by the present invention.

[0030] In the embodiments of the present invention, Bacillus subtilis (GDMCC NO.1.131), Bacillus megaterium (GDMCC NO.1.13), Streptomyces microflavus (GDMCC NO.4.26) and Azotobacter chroococcum (GDMCC NO.1.272) are all purchased from the Guangdong Provincial Microbial Culture Collection Center.

[0031] The preparation methods of the Bacillus subtilis bacterial solution, Bacillus megaterium bacterial solution, Streptomyces microflavus bacterial solution and Azotobacter chroococcum bacterial solution in the embodiments of the present invention include the following steps:

[0032] The activated strains are respectively added to a liquid medium for subculture, cultured at 30 °C for 48 h, and the bacterial solution concentration is adjusted to 1×10 8 cfu / mL;

[0033] The components of the liquid medium include: 3.0 g of beef extract, 5.0 g of peptone, 10.0 g of glucose, 1.0 g of sodium chloride, 0.5 g of potassium dihydrogen phosphate, 1.0 L of distilled water, and the pH is adjusted to 7.0.

[0034] The starch in the embodiments of the present invention is corn starch.

[0035] The polypropylene glycol diglycidyl ether in the embodiments of the present invention is purchased from Sigma-Aldrich, M n ≈380.

[0036] All "parts" in the embodiments of the present invention refer to parts by mass.

[0037] Example 1

[0038] A preparation method of a salt-reducing compound bacterial fertilizer, the preparation method of the salt-reducing compound bacterial fertilizer includes the following steps:

[0039] S1. Mix diatomaceous earth and Bacillus subtilis bacterial solution in a mass ratio of 1:1, stir evenly, stand for 2 h, and dry to obtain intermediate product 1;

[0040] Mix diatomaceous earth and Bacillus megaterium bacterial solution in a mass ratio of 1:1, stir evenly, stand for 2 h, and dry to obtain intermediate product 2;

[0041] Mix diatomaceous earth and Streptomyces microflavus bacterial solution in a mass ratio of 1:1, stir evenly, stand for 2 h, and dry to obtain intermediate product 3;

[0042] Mix diatomaceous earth and Azotobacter chroococcum bacterial liquid with a mass ratio of 1:1, stir evenly, let stand for 2 h, and dry to obtain intermediate product 4;

[0043] S2. Mix 20 parts of isopropanol and 15 parts of water as a solvent, add 10 parts of starch, then stir and add 0.9 part of sodium hydroxide. After reacting at 75 °C for 1 h, add 10 parts of polypropylene glycol diglycidyl ether, continue to react for 6 h, adjust the pH to 7.0 with glacial acetic acid after cooling, and obtain modified starch after centrifugation, washing, and drying;

[0044] S3. Add 40 g of modified starch and 40 g of starch to 800 g of water, stir at 80 °C for 5 min. After cooling, stir and add a mixture of 20 g of intermediate product 1 and 80 g of water, then add 0.6 g of sodium hexametaphosphate, let stand for 12 h, and dry to obtain coated strain 1;

[0045] Add 40 g of the modified starch and 40 g of starch to 800 g of water, stir at 80 °C for 5 min. After cooling, stir and add a mixture of 20 g of intermediate product 2 and 80 g of water, then add 0.6 g of sodium hexametaphosphate, let stand for 12 h, and dry to obtain coated strain 2;

[0046] Add 40 g of the modified starch and 40 g of starch to 800 g of water, stir at 80 °C for 5 min. After cooling, stir and add a mixture of 20 g of intermediate product 3 and 80 g of water, then add 0.6 g of sodium hexametaphosphate, let stand for 12 h, and dry to obtain coated strain 3;

[0047] Add 40 g of the modified starch and 40 g of starch to 800 g of water, stir at 80 °C for 5 min. After cooling, stir and add a mixture of 20 g of intermediate product 4 and 80 g of water, then add 0.6 g of sodium hexametaphosphate, let stand for 12 h, and dry to obtain coated strain 4;

[0048] Mix coated strain 1, coated strain 2, coated strain 3, and coated strain 4 with a mass ratio of 1:1:1:1 to obtain a salt-reducing compound bacterial fertilizer.

[0049] Example 2

[0050] A preparation method of a salt-reducing compound bacterial fertilizer, the preparation method of the salt-reducing compound bacterial fertilizer includes the following steps:

[0051] S1. Mix diatomaceous earth and Bacillus subtilis bacterial liquid with a mass ratio of 1:1, stir evenly, let stand for 2 h, and dry to obtain intermediate product 1;

[0052] Mix diatomaceous earth and Bacillus megaterium bacterial liquid with a mass ratio of 1:1, stir evenly, let stand for 2 h, and dry to obtain intermediate product 2;

[0053] Mix diatomaceous earth and Streptomyces microflavus bacterial liquid in a mass ratio of 1:1, stir evenly, let stand for 2 h, and dry to obtain intermediate product 3;

[0054] Mix diatomaceous earth and Azotobacter chroococcum bacterial liquid in a mass ratio of 1:1, stir evenly, let stand for 2 h, and dry to obtain intermediate product 4;

[0055] S2. Mix 20 parts of isopropanol and 15 parts of water as a solvent, add 10 parts of starch, then stir and add 0.9 part of sodium hydroxide. After reacting at 75 °C for 1 h, add 10 parts of polypropylene glycol diglycidyl ether and continue to react for 6 h. After cooling, adjust the pH to 7.0 with glacial acetic acid, centrifuge, wash, and dry to obtain modified starch;

[0056] S3. Add 40 g of modified starch and 40 g of starch to 800 g of water, stir at 80 °C for 5 min. After cooling, stir and add a mixture of 20 g of intermediate product 1 and 80 g of water, then add 0.6 g of sodium hexametaphosphate, let stand for 12 h, and dry to obtain coated strain 1;

[0057] Add 40 g of the modified starch and 40 g of starch to 800 g of water, stir at 80 °C for 5 min. After cooling, stir and add a mixture of 20 g of intermediate product 2 and 80 g of water, then add 0.6 g of sodium hexametaphosphate, let stand for 12 h, and dry to obtain coated strain 2;

[0058] Add 40 g of the modified starch and 40 g of starch to 800 g of water, stir at 80 °C for 5 min. After cooling, stir and add a mixture of 20 g of intermediate product 3 and 80 g of water, then add 0.6 g of sodium hexametaphosphate, let stand for 12 h, and dry to obtain coated strain 3;

[0059] Add 40 g of the modified starch and 40 g of starch to 800 g of water, stir at 80 °C for 5 min. After cooling, stir and add a mixture of 20 g of intermediate product 4 and 80 g of water, then add 0.6 g of sodium hexametaphosphate, let stand for 12 h, and dry to obtain coated strain 4;

[0060] Mix coated strain 1, coated strain 2, coated strain 3, and coated strain 4 in a mass ratio of 2:1:1:0.5 to obtain a salt-reducing compound bacterial fertilizer.

[0061] Example 3

[0062] A preparation method of a salt-reducing compound bacterial fertilizer, the preparation method of the salt-reducing compound bacterial fertilizer includes the following steps:

[0063] S1. Mix diatomaceous earth and Bacillus subtilis bacterial liquid in a mass ratio of 1:1, stir evenly, let stand for 2 h, and dry to obtain intermediate product 1;

[0064] Mix diatomaceous earth and Bacillus megaterium bacterial liquid in a mass ratio of 1:1, stir evenly, let stand for 2 h, and dry to obtain intermediate product 2;

[0065] Mix diatomaceous earth and Streptomyces microflavus bacterial liquid in a mass ratio of 1:1, stir evenly, let stand for 2 h, and dry to obtain intermediate product 3;

[0066] Mix diatomaceous earth and Azotobacter chroococcum bacterial liquid in a mass ratio of 1:1, stir evenly, let stand for 2 h, and dry to obtain intermediate product 4;

[0067] S2: Mix 20 parts of isopropanol and 15 parts of water as a solvent, add 10 parts of starch, then stir and add 0.9 part of sodium hydroxide. After reacting at 75 °C for 1 h, add 10 parts of polypropylene glycol diglycidyl ether, continue to react for 6 h, adjust the pH to 7.0 with glacial acetic acid after cooling, and obtain modified starch after centrifugation, washing, and drying;

[0068] S3: Add 40 g of modified starch and 40 g of starch to 800 g of water, stir at 80 °C for 5 min. After cooling, stir and add a mixture of 20 g of intermediate product 1 and 80 g of water, then add 0.6 g of sodium hexametaphosphate, let stand for 12 h, and obtain coated strain 1 after drying;

[0069] Add 40 g of the modified starch and 40 g of starch to 800 g of water, stir at 80 °C for 5 min. After cooling, stir and add a mixture of 20 g of intermediate product 2 and 80 g of water, then add 0.6 g of sodium hexametaphosphate, let stand for 12 h, and obtain coated strain 2 after drying;

[0070] Add 40 g of the modified starch and 40 g of starch to 800 g of water, stir at 80 °C for 5 min. After cooling, stir and add a mixture of 20 g of intermediate product 3 and 80 g of water, then add 0.6 g of sodium hexametaphosphate, let stand for 12 h, and obtain coated strain 3 after drying;

[0071] Add 40 g of the modified starch and 40 g of starch to 800 g of water, stir at 80 °C for 5 min. After cooling, stir and add a mixture of 20 g of intermediate product 4 and 80 g of water, then add 0.6 g of sodium hexametaphosphate, let stand for 12 h, and obtain coated strain 4 after drying;

[0072] Mix coated strain 1, coated strain 2, coated strain 3, and coated strain 4 in a mass ratio of 1:1:1:1 to obtain a salt-reducing compound bacterial fertilizer;

[0073] S4: Mix 4 parts of the salt-reducing compound bacterial fertilizer, 3 parts of urea, 6 parts of diammonium hydrogen phosphate, and 3 parts of potassium sulfate to obtain the product.

[0074] Comparative Example 1

[0075] A preparation method of a salt-reducing compound bacterial fertilizer, the preparation method of the salt-reducing compound bacterial fertilizer comprising the following steps:

[0076] Mix Bacillus subtilis bacterial liquid, Bacillus megaterium bacterial liquid, Streptomyces microflavus bacterial liquid, Azotobacter chroococcum bacterial liquid and diatomite in a mass ratio of 1:1:1:1:4, stir evenly and then stand for 2 h, and dry to obtain an intermediate product;

[0077] Add 80 g of starch to 800 g of water, stir at 80 °C for 5 min, after cooling, stir and add a mixed solution of 20 g of the intermediate product and 80 g of water, then add 0.6 g of sodium hexametaphosphate, stand for 12 h, and dry to obtain the salt-reducing compound bacterial fertilizer.

[0078] Comparative Example 2

[0079] Mix 4 parts of the salt-reducing compound bacterial fertilizer obtained in Comparative Example 1, 3 parts of urea, 6 parts of diammonium hydrogen phosphate and 3 parts of potassium sulfate to obtain a product.

[0080] Test Example 1

[0081] Perform performance tests on the fertilizer samples prepared in Example 3 and Comparative Example 2.

[0082] Test method:

[0083] Take 5 kg of planting soil and add it to flower pots, a total of 10 pots, set into 2 groups, with 5 pots in each group. Add the fertilizer samples prepared in Example 3 or Comparative Example 2 to each group at 100 g / pot respectively, and mix evenly.

[0084] After germinating and raising seedlings of the lettuce seeds, select the seedlings with the same growth vigor (after the first true leaf grows), transplant 3 plants / pot into the flower pots, and cultivate at a constant temperature of 25 °C for 30 d. During this period, the management of the lettuce follows the agricultural operations.

[0085] Measure the average weight of the above-ground part of the lettuce after cultivation.

[0086] The test results are shown in Table 1.

[0087] Table 1 Test results

[0088] Project Example 3 Comparative Example 2 Lettuce weight / g 138.8 121.5

[0089] It can be concluded from Table 1 that the salt-reducing compound bacterial fertilizer prepared in the examples of the present invention has a good promoting effect on the growth of lettuce. However, for the comparative example samples directly mixing different bacterial liquids and coated with conventional starch, due to the reduction of stability and the antagonistic and inhibitory effects between strains, it is difficult to obtain an ideal synergistic effect, and the growth-promoting effect on lettuce is relatively poor.

[0090] Test Example 2

[0091] Salt-reducing performance test.

[0092] Test method:

[0093] Take 20 g of the fertilizer samples prepared in Example 1 and Comparative Example 1 respectively, add them to 5 kg of local salinized soil (water content is 20 wt%), put them into flower pots, and treat them at a constant temperature of 30 °C for 30 d.

[0094] Take the soil and deionized water before (after) treatment, mix and extract them at a mass ratio of 1:5, and measure the conductivity of the solution.

[0095] The test results are shown in Table 2.

[0096] Table 2 Test Results

[0097]

[0098] It can be seen from Table 2 that adding the bacterial fertilizer of the embodiment of the present invention to the salinized soil for cultivation can effectively reduce the soil conductivity, proving that the soluble salt content is greatly reduced.

[0099] In summary, the present invention can significantly improve the salinization and alkalization defects of the soil, and at the same time can efficiently promote the growth of crops, and has good application prospects.

[0100] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

[0101] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A preparation method of a salt-reducing compound bacterial fertilizer, characterized in that, The preparation method of the salt-reducing compound bacterial fertilizer comprises the following steps: S1. Mix diatomite and the compound bacterial strain liquid respectively, adsorb and dry to obtain an intermediate product; S2. Mix starch and sodium hydroxide and heat, then add polypropylene glycol diglycidyl ether and continue to react to obtain modified starch; S3. Heat the modified starch and starch, then add the intermediate product and a cross-linking agent, and stir and react to obtain the salt-reducing compound bacterial fertilizer.

2. The preparation method of the salt-reducing compound bacterial fertilizer according to claim 1, characterized in that, It further includes: S4. Mix the salt-reducing compound bacterial fertilizer with nutrients.

3. The preparation method of the salt-reducing compound bacterial fertilizer according to claim 1, characterized in that In step S2, the heating temperature is 60-80 °C.

4. The preparation method of the salt-reducing compound bacterial fertilizer according to claim 1, characterized in that In step S2, the mass ratio of the starch, sodium hydroxide, and polypropylene glycol diglycidyl ether is 10:(0.5-1):(5-15).

5. The preparation method of the salt-reducing compound microbial fertilizer according to claim 1, wherein, In step S3, the heating temperature is 60-80 °C.

6. The preparation method of the salt-reducing compound bacterial fertilizer according to claim 1, characterized in that, In step S3, the mass ratio of the modified starch to the starch is (0.5-1):

1.

7. The preparation method of the salt-reducing compound bacterial fertilizer according to claim 1, characterized in that, The compound bacterial strains include Bacillus subtilis, Bacillus megaterium, Streptomyces microflavus, and Azotobacter chroococcum.

8. The preparation method of the salt-reducing compound bacterial fertilizer according to claim 2, characterized in that, The nutrients include urea, diammonium hydrogen phosphate, and potassium sulfate.

9. The preparation method of the salt-reducing compound bacterial fertilizer according to claim 1, characterized in that, The cross-linking agent is sodium hexametaphosphate.

10. Application of the preparation method of the salt-reducing compound bacterial fertilizer according to any one of claims 1-9 in agriculture.

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