A microbial agent for promoting potassium conversion in cotton fields and preparation method thereof

Abstract

The present invention discloses a microbial agent for promoting potassium conversion in cotton fields and a preparation method thereof, and belongs to the technical field of microbial materials. The present invention screens three strains of efficient potassium-solubilizing and growth-promoting microbial strains, which have excellent growth-promoting characteristics, have the ability to produce IAA and iron carriers, effectively optimize the potassium ratio in cotton fields, and promote the absorption of potassium by cotton plants; use brown algae oligosaccharide-nanoprotein composite particles to form microbial activators to enhance the activity of functional strains; use materials such as diatomaceous earth and biochar, and the porous structure and a wide variety of functional groups can attract potassium ions in the soil, reducing the loss of available potassium. The microbial agent obtained by the present invention can adjust the soil potassium structure, reduce the use of potassium fertilizers, and improve the quality of cotton yield. In cotton planting areas, it will have potential application prospects and is worthy of promotion and application.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial materials, and particularly relates to a microbial agent for promoting potassium conversion in cotton fields and a preparation method thereof. Background Art

[0002] Potassium is one of the key factors affecting the growth, development, quality and high yield of cotton. Improving the potassium level in the soil can effectively improve the photosynthetic characteristics of cotton leaves and promote cotton yield. However, potassium resources are currently in short supply, and it is difficult to regulate resources in China. Cotton is a potassium-loving crop, and potassium deficiency will significantly affect the photosynthetic rate of cotton functional leaves and root gene expression, resulting in reduced yield.

[0003] Since the 1980s, potassium fertilizers have been widely used, but long-term and continuous application of potassium fertilizers has led to an overabundance of potassium fertilizers and reduced utilization efficiency, and the phenomenon of soil potassium deficiency and reduced production has appeared one after another. In current cotton production, on the one hand, the content of available potassium in the soil is declining year by year, and on the other hand, there are abundant potassium reserves in the soil, and about 90%-98% of the soil potassium exists in silicate minerals. Therefore, under the general trend of sustainable agricultural development, it may be more economical and feasible to convert fixed slow-release potassium into available potassium that can be absorbed by plants.

[0004] In the prior art, in order to improve the potassium level in the soil, some soil conditioners or activators are basically used to promote the conversion of potassium. For example, the patent application with application number CN200510016620.5 discloses a soil biological activator, which belongs to the field of agricultural technology. It is composed of 0.1-0.3 parts by weight of allantoin and 0.7-0.9 parts by weight of biochemical humic acid. When used in combination with bacterial fertilizer, it can enhance the activation ability and nitrogen fixation ability of bacterial fertilizer on insoluble phosphorus and potassium in the soil, improve soil fertility, improve the nutritional conditions of plants, and thus increase crop yield and improve quality.

[0005] The Chinese patent application with application number CN202111384548.7 discloses a soil conditioner and a preparation method thereof. The soil conditioner includes the following parts by weight: 67-78 parts of calcium magnesium phosphate fertilizer, 20-30 parts of potassium humate, and 2-3 parts of trace elements, wherein the trace elements are zinc and boron. Through the use of activated potassium humate or potassium humate, the potassium cation exchange capacity in the soil is increased, the soil pH is adjusted, the formation of soil aggregate structure is promoted, the nutrient deficiency of crops is prevented and treated, the disease resistance of crops is enhanced, the yield of crops is increased, and the quality of crops is improved.

[0006] However, the current existing technologies have complex ingredients, single functions, and poor targeting. When applying chemical fertilizers, a large amount of such soil conditioners are also needed, which increases the burden on the soil. Although the yield and quality of crops can be improved in the current season, it is difficult to obtain a sustained and stable effect, so there is no practical application value. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention screens functional microbial strains and prepares a composite microbial agent combination, which, on the one hand, promotes the release of mineral potassium and the conversion of non-exchangeable potassium into exchangeable potassium, thereby promoting the release of soil potassium and improving the effectiveness of soil potassium; on the other hand, it can promote crop growth and improve crop yield and quality.

[0008] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0009] A microbial agent for promoting potassium conversion in cotton fields comprises Bacillus circulans, Saccharomyces paradoxus, Pseudomonas kunmingensis, a microbial activator and auxiliary materials.

[0010] The deposit number of the Bacillus circulans is CGMCC No.1.8826, and the original deposit date is October 21, 2008; the deposit number of the Saccharomyces cerevisiae is CGMCC No.2.5692, and the original deposit date is December 5, 2016; the deposit number of the Pseudomonas kunmingensis is CGMCC No.1.16086, and the original deposit date is January 15, 2017; all three strains are purchased from the China General Microorganism Collection Center, and can be purchased through public catalog inquiries without repeated biological deposits.

[0011] Furthermore, the microbial activator comprises glucose, brown algae oligosaccharide-nanoprotein composite particles and sodium alginate, and the mass ratio of the three is 10:1:0.5.

[0012] Furthermore, the preparation method of the brown algae oligosaccharide-nanoprotein composite particles is as follows: 50g of zein and 10g of brown algae oligosaccharide are co-dissolved in 500mL of 70% ethanol solution by volume, and then 5g of sophora biosurfactant is added, and stirred for 1h to obtain a mixed solution; then, under magnetic stirring, the mixed solution is slowly injected into an equal volume of deionized water, and magnetic stirring is performed at a speed of 1000r / min for 30min, and the ethanol in the solution is removed by a rotary evaporator, and the solution is centrifuged at 5000r / min for 10min, and freeze-dried to obtain brown algae oligosaccharide-nanoprotein composite particles.

[0013] Furthermore, the auxiliary materials are diatomaceous earth, biochar, humic acid, mushroom residue, potassium dihydrogen phosphate, and calcium carbonate, and the mass ratio is 10:10:10:5:0.5:0.1.

[0014] A method for preparing a microbial agent for promoting potassium conversion in cotton fields comprises the following preparation steps:

[0015] (1) Preparation of microbial fermentation broth: The frozen fermentation strains of Bacillus circulans, Saccharomyces cerevisiae, and Pseudomonas kunmingensis were taken out and inoculated into LB medium respectively, and the strains were activated and cultured at a temperature of 28-30°C; after 24 hours, the activated strains were inoculated into LB medium for further culture at a temperature of 28-33°C and 180 rpm for 24-36 hours, and then inoculated into the fermentation medium at an inoculum size of 2%, and cultured until the effective viable count reached 1.0×10 8 cfu / mL, and the first-level seed liquid of the three strains was obtained; the first-level seed liquid was then inoculated into the fermentation medium, with an inoculation amount of 5%, a stirring speed of 180-220 rpm, and a temperature of 28-30°C until the effective viable count reached 5.0×10 10 cfu / mL, three fermentation broths were obtained, and then the three fermentation broths were mixed in a volume ratio of 1:1:1 to obtain microbial fermentation broth;

[0016] (2) Preparation of microbial activator: 50 g of zein and 10 g of brown algae oligosaccharide were dissolved in 500 mL of 70% ethanol solution, and 5 g of sophorolipid was added and stirred for 1 h to obtain a mixed solution; then, the mixed solution was slowly injected into an equal volume of deionized water under magnetic stirring, and magnetic stirring was performed at a speed of 1000 r / min for 30 min. The ethanol in the solution was removed by rotary evaporator, and the solution was centrifuged at 5000 r / min for 10 min. After freeze-drying, brown algae oligosaccharide-nanoprotein composite particles were obtained; the obtained brown algae oligosaccharide-nanoprotein composite particles were uniformly mixed with glucose and sodium alginate in proportion to obtain a microbial activator;

[0017] (3) mixing diatomaceous earth, biochar, humic acid, mushroom residue, potassium dihydrogen phosphate, and calcium carbonate uniformly, sterilizing the mixture, adding a microbial activator, and stirring again to obtain a mixture;

[0018] (4) The microbial fermentation liquid obtained in step (1) and the mixture obtained in step (3) are mixed and adsorbed at a solid-liquid ratio of 50 mL:30 g, and then dried to a water content of ≤5% to obtain a final product.

[0019] Furthermore, the fermentation medium in step (1) is composed of: 1.0%-2% glycerol, 1.0%-1.5% peptone, 1%-1.1% yeast extract powder, 0.3%-0.5% calcium carbonate, 0.1%-0.3% potassium dihydrogen phosphate, and the rest is water, calculated by mass percentage, the total amount is 100%, and the pH is natural.

[0020] All raw materials of the present invention are commercially available. Applying 2 kg of the fertilizer in the furrow of each mu of cotton field can increase the content of available potassium in the soil and promote the growth and development of cotton plants.

[0021] Beneficial effects:

[0022] 1) The present invention selects three strains of efficient potassium-solubilizing and growth-promoting microorganisms, among which Bacillus circulans can efficiently produce organic acid substances such as tartaric acid and citric acid, and can promote the weathering of potassium-containing minerals in cotton fields by lowering the pH value of the soil environment, so that the mineral potassium releases potassium ions for use by plants; the organic acids released by the screened Saccharomyces cerevisiae can easily react with metal atoms on the surface of minerals to form soluble complexes, destroy the structure of minerals, and promote the release of potassium; the screened Pseudomonas kunmingensis will produce a large amount of extracellular polysaccharides during contact with minerals, and some functional groups of these extracellular polysaccharides have a complexing effect, which can form bacteria-mineral complexes with minerals, and can form bacteria-mineral complexes with mineral surface particles Si 4+ 、Al 3+ and K + The three strains also have excellent growth-promoting properties, and have the ability to produce IAA and iron carriers. When mixed, they have a significant synergistic effect, effectively optimizing the potassium ratio in cotton fields and promoting the absorption of potassium by cotton plants.

[0023] 2) The present invention uses glucose, brown algae oligosaccharide-nanoprotein composite particles, and sodium alginate to form a microbial activator. On the one hand, while providing energy for the microbial strain, the brown algae oligosaccharide-nanoprotein composite particles with added sophorolipids can be prepared, and the activity of the functional strain can be improved, stimulating it to more efficiently play the role of potassium dissolving and promoting growth, thereby improving the utilization efficiency of potassium elements in crops;

[0024] 3) Use diatomaceous earth, biochar, humic acid, mushroom residue, potassium dihydrogen phosphate, calcium carbonate, etc. as auxiliary nutrients. On the one hand, diatomaceous earth, biochar and other materials can adsorb microorganisms, which act as microbial carriers. On the other hand, biochar, humic acid, mushroom residue and other ingredients can supplement organic nutrients for the soil. In particular, diatomaceous earth, biochar and other ingredients can maintain soil structure, improve water, fertilizer, gas and heat conditions, and maintain and improve soil fertility after being applied to the soil. At the same time, the porous structure and a wide variety of functional groups of both can attract potassium ions in the soil, and biochar can reduce water leakage and reduce the loss of available potassium;

[0025] 4) In summary, the bacterial agent obtained by the present invention can adjust the soil potassium structure, reduce the use of potassium fertilizer, and improve the quality of cotton yield. It will have potential application prospects in cotton-growing areas and is worthy of promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The figure is a potassium solubilization test result diagram of the microbial fermentation broth of Example 2 of the present invention and Comparative Examples 1-3. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below in conjunction with specific embodiments, but is not limited thereto.

[0028] Example 1

[0029] A microbial agent for promoting potassium conversion in cotton fields comprises Bacillus circulans, Saccharomyces paradoxus, Pseudomonas kunmingensis, a microbial activator and auxiliary materials.

[0030] The deposit number of the Bacillus circulans is CGMCC No.1.8826, and the original deposit date is October 21, 2008; the deposit number of the Saccharomyces cerevisiae is CGMCC No.2.5692, and the original deposit date is December 5, 2016; the deposit number of the Pseudomonas kunmingensis is CGMCC No.1.16086, and the original deposit date is January 15, 2017; all three strains are purchased from the China General Microorganism Collection Center, and can be purchased through public catalog inquiries without repeated biological deposits.

[0031] The microbial activator comprises glucose, brown algae oligosaccharide-nanoprotein composite particles and sodium alginate, and the mass ratio of the three is 10:1:0.5.

[0032] The preparation method of the brown algae oligosaccharide-nanoprotein composite particles is as follows: 50g of zein and 10g of brown algae oligosaccharide are co-dissolved in 500mL of 70% ethanol solution by volume, 5g of sophorolipid is added, and the mixture is stirred for 1h to obtain a mixed solution; then, under magnetic stirring, the mixed solution is slowly injected into an equal volume of deionized water, and magnetic stirring is performed at a speed of 1000r / min for 30min, ethanol in the solution is removed by a rotary evaporator, the solution is centrifuged at 5000r / min for 10min, and the brown algae oligosaccharide-nanoprotein composite particles are obtained after freeze-drying.

[0033] The auxiliary materials are diatomaceous earth, biochar, humic acid, mushroom residue, potassium dihydrogen phosphate, and calcium carbonate, and the mass ratio is 10:10:10:5:0.5:0.1.

[0034] A method for preparing a microbial agent for promoting potassium conversion in cotton fields comprises the following preparation steps:

[0035] (1) Preparation of microbial fermentation broth: The frozen fermentation strains of Bacillus circulans, Saccharomyces cerevisiae, and Pseudomonas kunmingensis were taken out and inoculated into LB medium respectively, and the strains were activated and cultured at a temperature of 28-30°C; after 24 hours, the activated strains were inoculated into LB medium for further culture at a temperature of 28-33°C and 180 rpm for 24 hours, and then inoculated into the fermentation medium at an inoculum size of 2%, and cultured until the effective viable count reached 1.0×10 8 cfu / mL, and the first-level seed liquid of the three strains was obtained; the first-level seed liquid was then inoculated into the fermentation medium with an inoculation amount of 5%, a stirring speed of 180 rpm, and a temperature of 28-30°C until the effective viable count reached 5.0×10 10 cfu / mL, three fermentation broths were obtained, and then the three fermentation broths were mixed in a volume ratio of 1:1:1 to obtain microbial fermentation broth;

[0036] (2) Preparation of microbial activator: 50 g of zein and 10 g of brown algae oligosaccharide were dissolved in 500 mL of 70% ethanol solution, and 5 g of sophorolipid was added and stirred for 1 h to obtain a mixed solution; then, the mixed solution was slowly injected into an equal volume of deionized water under magnetic stirring, and magnetic stirring was performed at a speed of 1000 r / min for 30 min. The ethanol in the solution was removed by rotary evaporator, and the solution was centrifuged at 5000 r / min for 10 min. After freeze-drying, brown algae oligosaccharide-nanoprotein composite particles were obtained; the obtained brown algae oligosaccharide-nanoprotein composite particles were uniformly mixed with glucose and sodium alginate in proportion to obtain a microbial activator;

[0037] (3) mixing diatomaceous earth, biochar, humic acid, mushroom residue, potassium dihydrogen phosphate, and calcium carbonate uniformly, sterilizing the mixture, adding a microbial activator, and stirring again to obtain a mixture;

[0038] (4) The microbial fermentation liquid obtained in step (1) and the mixture obtained in step (3) are mixed and adsorbed at a solid-liquid ratio of 50 mL:30 g, and then dried to a water content of ≤5% to obtain a final product.

[0039] The fermentation medium in step (1) is composed of: 1.0% glycerol, 1.0% peptone, 1% yeast extract powder, 0.3% calcium carbonate, 0.1% potassium dihydrogen phosphate, and the rest is water, the total amount is 100% by mass percentage, and the pH is natural.

[0040] All raw materials are commercially available. Applying 2 kg of the fertilizer in the furrows of each mu of cotton field can increase the content of available potassium in the soil and promote the growth and development of cotton plants.

[0041] Example 2

[0042] A microbial agent for promoting potassium conversion in cotton fields comprises Bacillus circulans, Saccharomyces paradoxus, Pseudomonas kunmingensis, a microbial activator and auxiliary materials.

[0043] The deposit number of the Bacillus circulans is CGMCC No.1.8826, and the original deposit date is October 21, 2008; the deposit number of the Saccharomyces cerevisiae is CGMCC No.2.5692, and the original deposit date is December 5, 2016; the deposit number of the Pseudomonas kunmingensis is CGMCC No.1.16086, and the original deposit date is January 15, 2017; all three strains are purchased from the China General Microorganism Collection Center, and can be purchased through public catalog inquiries without repeated biological deposits.

[0044] The microbial activator comprises glucose, brown algae oligosaccharide-nanoprotein composite particles and sodium alginate, and the mass ratio of the three is 10:1:0.5.

[0045] The preparation method of the brown algae oligosaccharide-nanoprotein composite particles is as follows: 50g of zein and 10g of brown algae oligosaccharide are co-dissolved in 500mL of 70% ethanol solution by volume, 5g of sophorolipid is added, and the mixture is stirred for 1h to obtain a mixed solution; then, under magnetic stirring, the mixed solution is slowly injected into an equal volume of deionized water, and magnetic stirring is performed at a speed of 1000r / min for 30min, ethanol in the solution is removed by a rotary evaporator, the solution is centrifuged at 5000r / min for 10min, and the brown algae oligosaccharide-nanoprotein composite particles are obtained after freeze-drying.

[0046] Furthermore, the auxiliary materials are diatomaceous earth, biochar, humic acid, mushroom residue, potassium dihydrogen phosphate, and calcium carbonate, and the mass ratio is 10:10:10:5:0.5:0.1.

[0047] A method for preparing a microbial agent for promoting potassium conversion in cotton fields comprises the following preparation steps:

[0048] (1) Preparation of microbial fermentation broth: The frozen fermentation strains of Bacillus circulans, Saccharomyces cerevisiae, and Pseudomonas kunmingensis were taken out and inoculated into LB medium respectively, and the strains were activated and cultured at a temperature of 28-30°C; after 24 hours, the activated strains were inoculated into LB medium for further culture at a temperature of 28-33°C and 180 rpm for 36 hours, and then inoculated into the fermentation medium at an inoculum size of 2%, and cultured until the effective viable count reached 1.0×10 8 cfu / mL, and the first-level seed liquid of the three strains was obtained; the first-level seed liquid was then inoculated into the fermentation medium with an inoculation amount of 5%, a stirring speed of 220 rpm, and a temperature of 28-30°C until the effective viable count reached 5.0×10 10 cfu / mL, three fermentation broths were obtained, and then the three fermentation broths were mixed in a volume ratio of 1:1:1 to obtain microbial fermentation broth;

[0049] (2) Preparation of microbial activator: 50 g of zein and 10 g of brown algae oligosaccharide were dissolved in 500 mL of 70% ethanol solution, and 5 g of sophorolipid was added and stirred for 1 h to obtain a mixed solution; then, the mixed solution was slowly injected into an equal volume of deionized water under magnetic stirring, and magnetic stirring was performed at a speed of 1000 r / min for 30 min. The ethanol in the solution was removed by rotary evaporator, and the solution was centrifuged at 5000 r / min for 10 min. After freeze-drying, brown algae oligosaccharide-nanoprotein composite particles were obtained; the obtained brown algae oligosaccharide-nanoprotein composite particles were uniformly mixed with glucose and sodium alginate in proportion to obtain a microbial activator;

[0050] (3) mixing diatomaceous earth, biochar, humic acid, mushroom residue, potassium dihydrogen phosphate, and calcium carbonate uniformly, sterilizing the mixture, adding a microbial activator, and stirring again to obtain a mixture;

[0051] (4) The microbial fermentation liquid obtained in step (1) and the mixture obtained in step (3) are mixed and adsorbed at a solid-liquid ratio of 50 mL:30 g, and then dried to a water content of ≤5% to obtain a final product.

[0052] The fermentation medium in step (1) is composed of: 2% glycerol, 1.5% peptone, 1.1% yeast extract powder, 0.5% calcium carbonate, 0.3% potassium dihydrogen phosphate, and the rest is water, with a total amount of 100% by mass and a natural pH.

[0053] Comparative Example 1

[0054] A microbial agent for promoting potassium conversion in cotton fields comprises Saccharomyces paradoxus, Pseudomonas kunmingensis, a microbial activator and auxiliary materials.

[0055] The preservation number of the Saccharomyces cerevisiae is CGMCC No. 2.5692, and the original preservation date is December 5, 2016; the preservation number of the Pseudomonas kunmingensis is CGMCC No. 1.16086, and the original preservation date is January 15, 2017; the strains are all purchased from the China General Microorganism Collection Center and can be purchased through public catalog inquiries without repeated biological preservation.

[0056] A method for preparing a microbial agent for promoting potassium conversion in cotton fields comprises the following preparation steps:

[0057] (1) Preparation of microbial fermentation broth: The frozen fermentation strains of Saccharomyces cerevisiae and Pseudomonas kunmingensis were taken out and inoculated into LB medium respectively, and the strains were activated and cultured at a temperature of 28-30°C; after 24 hours, the activated strains were inoculated into LB medium for further culture at a temperature of 28-33°C and 180 rpm for 36 hours, and then inoculated into the fermentation medium at an inoculum size of 2%, and cultured until the effective viable count reached 1.0×10 8 cfu / mL, and the first-level seed liquid of the two strains was obtained; the first-level seed liquid was then inoculated into the fermentation medium, with an inoculation amount of 5%, a stirring speed of 220 rpm, and a temperature of 28-30°C until the effective viable count reached 5.0×10 10 cfu / mL, two fermentation broths were obtained, and then the two fermentation broths were mixed in a volume ratio of 1:1 to obtain a microbial fermentation broth;

[0058] (2) Preparation of microbial activator: 50 g of zein and 10 g of brown algae oligosaccharide were dissolved in 500 mL of 70% ethanol solution, and 5 g of sophorolipid was added and stirred for 1 h to obtain a mixed solution; then, the mixed solution was slowly injected into an equal volume of deionized water under magnetic stirring, and magnetic stirring was performed at a speed of 1000 r / min for 30 min. The ethanol in the solution was removed by rotary evaporator, and the solution was centrifuged at 5000 r / min for 10 min. After freeze-drying, brown algae oligosaccharide-nanoprotein composite particles were obtained; the obtained brown algae oligosaccharide-nanoprotein composite particles were uniformly mixed with glucose and sodium alginate in proportion to obtain a microbial activator;

[0059] (3) mixing diatomaceous earth, biochar, humic acid, mushroom residue, potassium dihydrogen phosphate, and calcium carbonate uniformly, sterilizing the mixture, adding a microbial activator, and stirring again to obtain a mixture;

[0060] (4) The microbial fermentation liquid obtained in step (1) and the mixture obtained in step (3) are mixed and adsorbed at a solid-liquid ratio of 50 mL:30 g, and then dried to a water content of ≤5% to obtain a final product.

[0061] In this comparative example, except that Bacillus circulans was not used, the other raw materials and preparation method were the same as those in Example 2.

[0062] Comparative Example 2

[0063] Similar to Comparative Example 1, in this comparative example, except that Saccharomyces cerevisiae is not used, the remaining raw materials and preparation methods are the same as those of Example 2. That is, the steps for preparing the microbial fermentation liquid are:

[0064] The frozen fermentation strains Bacillus circulans and Pseudomonas kunmingensis were taken out and inoculated into LB medium respectively, and the strains were activated and cultured at a temperature of 28-30°C; after 24 hours, the activated strains were inoculated into LB medium for further culture at a temperature of 28-33°C and 180rpm for 36 hours, and then inoculated into the fermentation medium at an inoculum size of 2%, and cultured until the effective viable count reached 1.0×10 8 cfu / mL, and the first-level seed liquid of the two strains was obtained; the first-level seed liquid was then inoculated into the fermentation medium, with an inoculation amount of 5%, a stirring speed of 220 rpm, and a temperature of 28-30°C until the effective viable count reached 5.0×10 10 cfu / mL, two fermentation broths were obtained, and then the two fermentation broths were mixed in a volume ratio of 1:1 to obtain a microbial fermentation broth.

[0065] Comparative Example 3

[0066] Similar to Comparative Example 1, in this comparative example, except that Pseudomonas kunmingensis is not used, the remaining raw materials and preparation methods are the same as those of Example 2. That is, the steps for preparing the microbial fermentation broth are:

[0067] The frozen fermentation strains Bacillus circulans and Saccharomyces paradoxus were taken out and inoculated into LB medium respectively, and the strains were activated and cultured at a temperature of 28-30°C; after 24 hours, the activated strains were inoculated into LB medium for further culture at a temperature of 28-33°C and 180rpm for 36 hours, and then inoculated into the fermentation medium at an inoculum size of 2%, and cultured until the effective viable count reached 1.0×10 8 cfu / mL, and the first-level seed liquid of the two strains was obtained; the first-level seed liquid was then inoculated into the fermentation medium, with an inoculation amount of 5%, a stirring speed of 220 rpm, and a temperature of 28-30°C until the effective viable count reached 5.0×10 10 cfu / mL, two fermentation broths were obtained, and then the two fermentation broths were mixed in a volume ratio of 1:1 to obtain a microbial fermentation broth.

[0068] Comparative Example 4

[0069] A microbial agent for promoting potassium conversion in cotton fields comprises Bacillus circulans, Saccharomyces paradoxus, Pseudomonas kunmingensis, a microbial activator and auxiliary materials.

[0070] The microbial activator comprises glucose and sodium alginate, and the mass ratio of the two is 10:0.5.

[0071] In this comparative example, except that no brown algae oligosaccharide-nanoprotein composite particles were added to the microbial activator, the remaining raw materials and preparation methods were the same as those in Example 2.

[0072] Performance Testing

[0073] 1. Determine the strain's ability to dissolve potassium, produce IAA, and produce siderophore

[0074] The potassium-solubilizing capacity was determined by flame photometry. Reference: ZHANG CS, KONG F Y. Isolation and identification of potassium-solubilizing bacteria from tobaccorhizospheric oil and their effect on tobacco plants [J]. Appl Soil Ecol, 2014, 82: 18-25

[0075] The IAA production capacity was determined by the Salkowski colorimetric method. Reference: MOHITE B. Isolation and characterization of indole acetic acid (IAA) producing bacteria from rhizospheric soil and its effect on plant growth [J]. J Soil Sci Plant Nutr, 2013 (ahead).

[0076] The ability to produce siderophores was determined by CAS method, reference: SCHWYN B, NEILANDS J B. Universal chemical assay or the detection and determination of siderophores [J]. Anal Biochem, 1987, 160 (1): 47-56.

[0077] The measurement results are shown in Table 1:

[0078] Table 1 Test on the ability of strains to dissolve potassium and promote growth

[0079] strain Potassium dissolving capacity mg / L IAA production capacity mg / L Siderophore production capacity Bacillus circulans 25.01±0.12 12.01±0.14 ++ Saccharomyces cerevisiae 20.36±0.75 15.69±0.22 ++ Pseudomonas kunmingensis 16.22±0.51 14.22±0.11 +

[0080] Note: “-” indicates no iron carrier production, “+” indicates iron carrier production, and the more “+” the stronger the iron carrier production capacity is.

[0081] From the data in the table, we can see that the three strains screened by the present invention all have good potassium-solubilizing and growth-promoting effects.

[0082] To further verify the synergistic effect of the three strains, the microbial fermentation broth obtained in the examples and comparative examples of the present invention was tested for potassium-solubilizing ability. The test method is as follows: Quantitative test for potassium-solubilizing bacteria ability determination: 1% inoculation amount of the fermentation broth was inoculated into 100 mL of potassium-solubilizing liquid fermentation medium, and cultured in a constant temperature shaker at 120 r / min and 28-30°C for 7 days. The soluble potassium content was measured using a flame spectrophotometer. The enzyme experiment was repeated 5 times for each group, and the results were averaged. The test results are shown in Figure 1 shown.

[0083] Soil culture experiment

[0084] Physical and chemical properties of original soil: pH 7.05, water-soluble potassium 15.22 mg / kg, exchangeable potassium 49.47 mg / kg, non-exchangeable potassium 381.25 mg / kg, mineral potassium 15.88 g / kg.

[0085] The experiment was designed with 7 treatment groups, namely:

[0086] CK: 25 kg soil;

[0087] S1: 25kg soil + 3g bacterial agent obtained in Example 1;

[0088] S2: 25kg soil + 3g bacterial agent obtained in Example 2;

[0089] S3: 25kg soil + 3g bacterial agent obtained in Comparative Example 1;

[0090] S4: 25kg soil + 3g bacterial agent obtained in Comparative Example 2;

[0091] S5: 25kg soil + 3g bacterial agent obtained in Comparative Example 3;

[0092] S6: 25kg soil + 3g bacterial agent obtained in Comparative Example 4;

[0093] Each treatment was repeated 5 times, and the results were averaged. The soil of each treatment was mixed evenly, and the soil moisture content was adjusted to about 20%. It was cultured at room temperature for 28 days, and the soil indicators were measured. The test method was as follows: exchangeable potassium was extracted with neutral ammonium acetate, soil water-soluble potassium was extracted with distilled water, and non-exchangeable potassium was extracted with nitric acid boiling. The three potassium extracts were all measured with a flame photometer.

[0094] Table 2 Soil potassium content and proportion

[0095] Water soluble potassium mg / kg Exchangeable potassium mg / kg Non-exchangeable potassium mg / kg CK 15.36 50.12 381.33 Example 1 85.69 214.56 487.98 Example 2 89.14 211.78 489.56 Comparative Example 1 60.11 150.47 410.88 Comparative Example 2 68.14 165.11 411.15 Comparative Example 3 71.12 184.45 421.25 Comparative Example 4 80.47 198.89 445.89

[0096] From the data in Table 2, we can see that the use of the bacterial agent of the present invention can significantly increase the available potassium content in the soil, while in the comparative examples 1-4 in which the bacterial agent composition is changed and the activation component is missing, the synergistic balance between the strains is broken and the activation effect is weakened, and the activation ability of soil potassium in the comparative example group is significantly weakened.

[0097] Pot experiment:

[0098] The cotton variety tested was "Ji 228"

[0099] The experiment set up 7 treatments, each with 3 replicates, and the results were averaged. 25 kg of soil was used per pot. Before sowing cotton, the basal fertilizer and the bacterial agent were evenly spread on the soil surface and turned into the soil with tools. Regular observation was performed during the cultivation period, and watering was performed according to the actual soil conditions to keep the soil moist. All cotton was harvested according to the boll opening situation, and the number of picked cotton was recorded each time. After all the cotton was harvested, the weight of the seed cotton was counted and the weight of a single boll was calculated.

[0100] The experimental design is shown in Table 3:

[0101] Table 3 Fertilization design

[0102] Urea g / 25kg Superphosphate g / 25kg Potassium chloride g / 25kg Bacterial agent g / 25kg Conventional fertilization 9.5 6.1 6.1 - Example 1 9.5 6.1 - 3 Example 2 9.5 6.1 - 3 Comparative Example 1 9.5 6.1 - 3 Comparative Example 2 9.5 6.1 - 3 Comparative Example 3 9.5 6.1 - 3 Comparative Example 4 9.5 6.1 - 3

[0103] Table 4 Cotton yield and properties in different treatment groups

[0104]

[0105] From the data in Table 4, we can also see that the microbial agent of the embodiment of the present invention can replace potassium fertilizer and reduce the use of chemical potassium fertilizer. The cotton yield and quality are better than those of the conventional potassium fertilizer experimental group. It can be seen that the microbial agent of the present invention has a significant growth-promoting effect on cotton, and greatly improves the cotton yield and quality while reducing the use of potassium fertilizer.

[0106] It should be noted that the above embodiments are only some embodiments of the preferred methods of implementing the present invention, rather than all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A microbial agent for promoting potassium conversion in cotton fields, characterized in that: By Bacillus circulans ( Bacillus circulans )、Saccharomyces cerevisiae( Saccharomyces paradoxus , Pseudomonas kunmingensis ( Pseudomonas kunmingensis ), a microbial activator and auxiliary materials; the preservation number of the circulans Bacillus is CGMCC No.1.8826, the preservation number of the paradoxical yeast is CGMCC No.2.5692, and the preservation number of the Kunming Pseudomonas is CGMCC No.1.16086, all three strains were purchased from China General Microorganism Collection Center; the microbial activator consists of glucose, brown algae oligosaccharide-nanoprotein composite particles and sodium alginate, and the mass ratio of the three is 10:1:0.5; the preparation method of the brown algae oligosaccharide-nanoprotein composite particles is as follows: 50g of zein and 10g of brown algae oligosaccharide are co-dissolved in 500mL of 70% ethanol solution by volume, and then 5g of sophora biosurfactant is added, and stirred for 1h to obtain a mixed solution; then, under magnetic stirring, the mixed solution is slowly injected into an equal volume of deionized water, and magnetic stirring is performed at a speed of 1000r / min for 30min, the ethanol in the solution is removed by a rotary evaporator, and the brown algae oligosaccharide-nanoprotein composite particles are obtained after centrifugation at 5000r / min for 10min.

2. The microbial agent for promoting potassium conversion in cotton fields according to claim 1, characterized in that: The auxiliary materials are diatomaceous earth, biochar, humic acid, mushroom residue, potassium dihydrogen phosphate, and calcium carbonate, and the mass ratio is 10:10:10:5:0.5:0.

1.

3. A method for preparing the microbial agent for promoting potassium conversion in cotton fields according to any one of claims 1-2, characterized in that: The method comprises the following preparation steps: (1) Preparation of microbial fermentation broth: The frozen fermentation strains of Bacillus circulans, Saccharomyces cerevisiae, and Pseudomonas kunmingensis were taken out and inoculated into LB medium respectively, and the strains were activated and cultured at a temperature of 28-30°C. After 24 hours, the activated strains were inoculated into LB medium for further culture at a temperature of 28-33°C and 180 rpm for 24-36 hours, and then inoculated into the fermentation medium at an inoculum size of 2%, and cultured until the effective viable count reached 1.0×10 8 cfu / mL, and the first-level seed liquid of the three strains was obtained; the first-level seed liquid was then inoculated into the fermentation medium, with an inoculation amount of 5%, a stirring speed of 180-220 rpm, and a temperature of 28-30°C until the effective viable count reached 5.0×10 10 cfu / mL, three fermentation broths were obtained, and then the three fermentation broths were mixed in a volume ratio of 1:1:1 to obtain microbial fermentation broth; (2) Preparation of microbial activator: 50 g of zein and 10 g of brown algae oligosaccharide were dissolved in 500 mL of 70% ethanol solution, and then 5 g of sophorolipid was added and stirred for 1 h to obtain a mixed solution; then, the mixed solution was slowly injected into an equal volume of deionized water under magnetic stirring, and magnetic stirring was performed at a speed of 1000 r / min for 30 min. The ethanol in the solution was removed by rotary evaporator, and the solution was centrifuged at 5000 r / min for 10 min. After freeze-drying, brown algae oligosaccharide-nanoprotein composite particles were obtained; the obtained brown algae oligosaccharide-nanoprotein composite particles were uniformly mixed with glucose and sodium alginate in proportion to obtain a microbial activator; (3) mixing diatomaceous earth, biochar, humic acid, mushroom residue, potassium dihydrogen phosphate, and calcium carbonate uniformly, sterilizing the mixture, adding a microbial activator, and stirring again to obtain a mixture; (4) The microbial fermentation liquid obtained in step (1) and the mixture obtained in step (3) are mixed and adsorbed at a solid-liquid ratio of 50 mL:30 g, and then dried to a water content of ≤5% to obtain a final product.

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