Preparation method and application of saline-alkaline tolerant complex microbial inoculant

Abstract

The invention relates to the technical field of microorganisms and compositions thereof, and particularly discloses a preparation method and application of a saline-alkaline tolerant complex microbial inoculant. The saline-alkaline tolerant complex microbial inoculant is prepared from the following raw materials in parts by weight: 15-20 parts of an arbuscular mycorrhizal fungal spore mixture; 20 to 25 parts of a growth-promoting bacterium solution; 60-70 parts of a matrix; 4-5 parts of a nutrient substance; a strain in the growth-promoting bacterium liquid comprises one or more of enterobacter luviveilis, serratia marcescens and alcaligenes faecalis, and the matrix comprises common biochar and diatomite, and the microelement comprises one or more of the enterobacter luviveilis, the serratia marcescens and the alcaligenes faecalis. The preparation method comprises the following steps: S1, preparing a bacterial liquid; s2, carrier preparation; and S3, mixed fermentation. The product can be used for improving saline-alkali soil, the application amount is 2-4 kg / hm < 2 >, the product has the advantages of being high in survival rate and activity, and the organic matter content of soil and the survival rate of plants in saline-alkali soil can be effectively increased.

Description

Technical Field

[0001] The present application relates to the technical field of microorganisms and compositions thereof, and in particular to a preparation method and application of a salt-alkali resistant composite bacterial agent. Background Art

[0002] Soil salinization is a serious agricultural problem facing the world in recent years, which seriously affects the growth of crops and threatens food security. Especially under the influence of global climate change and human activities, this problem is becoming increasingly serious, affecting billions of hectares of land around the world, which in turn poses a huge challenge to agricultural production. In order to improve the quality of saline-alkali soil and increase crop yields, researchers and agricultural workers have been exploring effective soil improvement technologies and methods. These methods are not only related to the sustainability of agricultural production, but also involve the restoration and protection of land ecosystems, which is of great significance for achieving green and sustainable agricultural development. With the deepening of understanding of soil health and ecosystem balance, people's demand for soil improvement technology has gradually increased, hoping to solve the salinization problem in a more environmentally friendly and sustainable way, thereby providing a solid guarantee for food security.

[0003] At present, in order to improve saline-alkali soil, physical and chemical methods such as deep plowing and applying soil conditioners are usually used, but these methods are often costly and may cause secondary pollution. For example, the salt in chemical conditioners may further aggravate the salinization of the soil, lead to the destruction of soil structure, reduce soil fertility, and ultimately make agricultural farming unsustainable. In addition, although physical methods such as deep plowing can alleviate the salinization phenomenon on the soil surface to a certain extent, due to its limited range of action, the improvement effect on deep soil is not obvious. In addition to the above-mentioned physical and chemical methods, there are other representative improvement technologies, such as improving soil quality by planting salt-alkali tolerant plants, or using microbial agents to regulate the structure of soil microbial communities through biological methods to enhance soil ecological functions. At this time, microbial agents are regarded as a technology with great potential due to their environmentally friendly characteristics. This technology can restore soil fertility by promoting the recycling of nutrients, thereby improving the growth performance of crops, and the degree of damage to soil structure is minimal, and the probability of secondary pollution is almost zero.

[0004] However, although this method can effectively solve the problems caused by soil salinization, there are still some challenges that need to be solved. The problems of low survival rate and activity of microbial agents used in the prior art in saline-alkali soils are particularly prominent, which leads to unsatisfactory soil improvement effects. Specifically, due to the poor living conditions of microorganisms in saline-alkali environments, it is difficult for the beneficial bacteria in the agents to remain active for a long time and cannot effectively play their role in soil improvement. In addition, the high salt content in saline-alkali soils will also inhibit the metabolism of microorganisms and weaken their ability to degrade harmful substances, limiting the soil improvement effect. Therefore, it is urgent to develop a new type of microbial agent that can maintain a high survival rate and high activity in a saline-alkali environment, so as to effectively improve the soil improvement effect. Summary of the invention

[0005] In order to effectively improve the soil improvement effect, the present application provides a preparation method and application of a salt-alkali resistant composite bacterial agent.

[0006] In the first aspect, the present application provides a salt-alkali tolerant composite bacterial agent, the raw materials used include the following components in parts by weight: 15-20 parts of a mixture of arbuscular mycorrhizal fungi spores; 20-25 parts of a growth-promoting bacterial liquid; 60-70 parts of a matrix; and 4-5 parts of nutrients; the bacterial species in the growth-promoting bacterial liquid include one or more of Enterobacter ludwigii, Serratia marcescens and Alcaligenes faecalis, and the matrix includes ordinary biochar and diatomaceous earth.

[0007] The preparation method of the arbuscular mycorrhizal fungal spore mixture is as follows: first, the red clover seeds are disinfected and set aside, and then the propagation matrix is ​​sterilized and set aside, and then the red clover seeds, the propagation matrix and the arbuscular mycorrhizal fungi are mixed, and propagated for 30 days under the conditions of a temperature of 23-28°C and a light of 15-16h / d, the above-ground plant body is removed, and the root segments in the propagation matrix are harvested after drying in the shade, and crushed through a 2mm sieve to obtain the arbuscular mycorrhizal fungal spore mixture.

[0008] By adopting the above technical scheme, the present application utilizes the compounding of arbuscular mycorrhizal fungal spore mixture and growth-promoting bacterial solution, wherein the arbuscular mycorrhizal fungal spore mixture can form a symbiotic body with plants and secrete organic acids, promoting the conversion and activation of soil nutrients by plant roots, and one or more of Ludwig Enterobacter, Serratia marcescens and Alcaligenes faecalis can cooperate with the arbuscular mycorrhizal fungal spore mixture, thereby significantly promoting the absorption of nutrients by plants and improving the permeability of mycelium of plant roots. The effect is particularly obvious in saline-alkali soils, which can protect plant pathogens and reduce the abiotic stress of salt and heavy metals on plants, thereby promoting the efficient recycling of nutrients in saline-alkali soils, and quickly restoring the fertility of saline-alkali soils, thereby greatly improving the organic matter content of saline-alkali soils and the survival rate of plants. Compared with other growth-promoting bacteria (Bacillus subtilis and Acinetobacter beijerinii), the growth-promoting bacteria of the present application have a better synergistic effect with the arbuscular mycorrhizal fungal spore mixture, and can greatly improve the organic matter content of saline-alkali soils and the survival rate of plants within the same treatment time.

[0009] The arbuscular mycorrhizal fungal spore mixture, growth-promoting bacterial liquid, matrix and nutrients of the present application can be mixed in a certain way to produce a salt-alkali tolerant composite bacterial agent with high survival rate and high activity, which greatly improves the improvement effect of saline-alkali soil. Experimental data show that compared with untreated saline-alkali soil, the organic matter content of the saline-alkali soil treated with the salt-alkali tolerant composite bacterial agent of the present application can be increased by more than 104%, and the plant survival rate can be increased by 175% or more, which is of great significance for improving the salinization problem.

[0010] The nutrients of the present application include nitrates, phosphates and potassium salts, which can provide sufficient nitrogen, phosphorus and potassium nutrients. Those skilled in the art can reasonably select different nutrients according to actual conditions, comprehensive material resources and economic effects. The present application only uses ammonium nitrate, potassium chloride and apatite as examples for illustration, and does not limit the scope of protection of the present application accordingly.

[0011] Preferably, the bacterial species in the growth-promoting bacterial liquid include Serratia marcescens and Alcaligenes faecalis with an effective live bacteria number ratio of (2-3):1.5.

[0012] Preferably, the ratio of the number of effective live bacteria of Serratia marcescens to Alcaligenes faecalis is 2.8:1.5.

[0013] By adopting the above-mentioned technical scheme, the present application utilizes a combination of Serratia marcescens and Alcaligenes faecalis with a certain ratio of effective live bacteria as the strains in the growth-promoting bacterial liquid. The growth-promoting effect between these two bacteria is significantly better than other combinations. On this basis, further adjusting the ratio of effective live bacteria can maximize the synergistic effect of the two, thereby increasing the organic matter content by 165% and the plant survival rate by 198%.

[0014] Preferably, the matrix further comprises acidic biochar added in an amount of 2-8 wt % of the total amount of the matrix.

[0015] The acidic biochar is prepared by the following method: ordinary biochar and acid solution are mixed evenly, allowed to stand, filtered, and solids are washed until the pH of the washing liquid is constant, and then dried, ground, and sieved to obtain acid-modified biochar.

[0016] By adopting the above technical solution, the present application adds a certain amount of acidic biochar to the matrix, so that the salt-alkali tolerant composite bacterial agent has a certain ability to promote water infiltration when used, and at the same time makes the salt-alkali tolerant composite bacterial agent more closely combined with the soil, enhancing the water absorption and water retention of the soil, thereby increasing the moisture content near the roots of the plants, thereby increasing the survival rate of the plants. In addition, the present application controls the amount of acidic biochar added, further improving the survival rate of the plants. If the amount added is too little, it will not effectively promote the infiltration of water; if the amount added is too large, it will absorb water that exceeds the needs of the plants to the soil at the roots of the plants, which will cause the plants to be subjected to abiotic stress from water, reducing the survival rate of the plants and the organic matter content in the soil.

[0017] Preferably, the amount of acidic biochar added is 5wt% of the total amount of the matrix.

[0018] By adopting the above technical solution, the application strictly controls the amount of acidic biochar added. At this time, the plant survival rate reaches the highest, and testing has shown that it can be increased by as much as 19% compared to before.

[0019] Preferably, the raw materials used also include 13-15 parts by weight of a dispersing aid, and the dispersing aid includes SDBS, CMC and ammonium sulfate in a weight ratio of (6-8):6:(4-5).

[0020] Since there is still room for improvement in the dispersibility and permeability of the salt-alkali tolerant composite bacterial agent in saline-alkali soil, the present application adopts the above-mentioned technical scheme and also adds a dispersing aid composed of a certain ratio of SDBS, CMC and ammonium sulfate, which greatly improves the dispersion and penetration ability of the salt-alkali tolerant composite bacterial agent in the soil, so that it can more efficiently improve the saline-alkali soil conditions, thereby further improving the organic matter content of the saline-alkali soil and the survival rate of plants.

[0021] In a second aspect, the present application provides a method for preparing a salt-alkali resistant composite bacterial agent, comprising the following steps: S1. Preparation of bacterial solution: The growth-promoting bacteria were cultured in the first stage and inoculated to obtain an effective viable bacterial count of 0.8×10 8 CFU / mL-1×10 8 CFU / mL of growth-promoting bacteria solution for later use; S2, carrier preparation: drying the matrix, crushing and sieving, sterilizing to obtain the carrier for later use; S3, mixed fermentation: the growth-promoting bacterial liquid obtained in step S1 is mixed with the carrier obtained in step S2, and then the arbuscular mycorrhizal fungal spore mixture and nutrients are added, fermented, granulated and passed through a 0.5-1.0 mm sieve, and dried to a constant weight of the system to obtain a salt-alkali resistant composite bacterial agent.

[0022] By adopting the above technical solution, the present application firstly cultured and obtained an effective viable bacterial count of 0.8×10 8 CFU / mL-1×10 8 CFU / mL of bacterial liquid is mixed with a carrier obtained by drying, crushing and sterilizing the matrix, and then fermented together with a mixture of arbuscular mycorrhizal fungi spores and nutrients. The salt-alkali resistant composite bacterial agent is obtained by granulation, sieving and drying. Compared with the existing powdered composite bacterial agents without granulation, it has higher dispersibility, stability and environmental friendliness, and has high practical use value.

[0023] Preferably, in step S3, the granules are sieved through a 0.8 mm sieve.

[0024] By adopting the above technical scheme, the present application strictly controls the size of the screening screen after granulation. The unit number of viable bacteria of the salt-alkali tolerant composite bacterial agent at this particle size is the highest, and the improvement effect on saline-alkali soil is also the strongest. Compared with the salt-alkali tolerant composite bacterial agents at other particle sizes, it can increase the organic matter content and plant survival rate by more than 14% and 11% respectively.

[0025] Preferably, in step S3, when the growth-promoting bacteria solution, the carrier, the arbuscular mycorrhizal fungal spore mixture and the nutrients are mixed, a dispersing aid is also added.

[0026] In the third aspect, the present application provides an application of a salt-alkali tolerant composite bacterial agent, wherein the application amount of the salt-alkali tolerant composite bacterial agent is 2-4 kg / hm 2 .

[0027] By adopting the above technical scheme, the salt-alkali tolerant composite bacterial agent of the present application has high activity and high survival rate, so it can improve the saline-alkali soil condition very efficiently and quickly. 2 It can play a significant role in any situation, and has a very wide range of applications and high competitiveness.

[0028] In summary, this application has the following beneficial technical effects: 1. The salt-alkali tolerant composite bacterial agent of the present application has greatly improved the improvement effect of saline-alkali soil. Experimental data show that compared with untreated saline-alkali soil, the organic matter content of the treated saline-alkali soil can be increased by more than 104%, and the plant survival rate can be increased by 175% or more, which is of great significance for improving the salinization problem; 2. The preparation method of the present application includes granulation and screening, and the obtained salt-alkali resistant composite bacterial agent has higher dispersibility, stability and environmental friendliness than the existing powdered composite bacterial agent without granulation, and has high practical use value; 3. The salt-alkali tolerant composite bacterial agent of the present application has high activity and high survival rate, so it can improve the saline-alkali soil conditions very efficiently and quickly. 2 It can have a significant effect under the circumstances. DETAILED DESCRIPTION

[0029] Material Source Unless otherwise specified, the raw materials used in this application are all commercially available products, specifically: Red clover seeds were purchased from Jiangsu Hengxin Seed Co., Ltd.; Red soil was purchased from Sichuan Qing Building Materials Factory, Lingshou County; River sand was purchased from Yongshun Mineral Products Processing Plant in Lingshou County; The clump mycorrhizal fungi were provided by the Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences; Ordinary biochar is wheat straw provided by an agricultural technology company, which is obtained by carbonizing at 600℃ for 5h. The volume mass is 0.19g / cm 3 , specific surface area 9m 2 / g, porosity 67%, pH = 10.24. Those skilled in the art can also reasonably select different materials as the starting materials of ordinary biochar according to the actual situation, comprehensive resources and economic effects, such as rice husks, sawdust and other materials. The application selects wheat straw only for simple explanation and does not limit the protection scope of the application accordingly. Enterobacter ludwigii, Serratia marcescens, Alcaligenes faecalis, and Acinetobacter beijerinii were provided by Harbin Normal University; Diatomaceous earth was purchased from the Never Stop Mineral Products Business Department in Lingshou County; Apatite was purchased from Wuhan Jushun Chemical Co., Ltd.; SDBS and CMC were purchased from Sinopharm Chemical Reagent Co., Ltd.; Talc was purchased from Yongshun Mineral Products Processing Plant in Lingshou County; Bacillus subtilis was purchased from China Agricultural Microorganism Collection Center.

[0030] The present application is further described in detail below in combination with preparation examples, embodiments and comparative examples.

[0031] Preparation Example 1.1 The method for preparing the arbuscular mycorrhizal fungal spore mixture comprises the following steps: First, the red clover seeds were disinfected with 3% hydrogen peroxide for 5 minutes and then the propagation matrix was sterilized at 121°C for 1 hour. The propagation matrix included red soil and river sand in a ratio of 1:1. 2 / 3 of the sterilized propagation matrix was filled in the propagation container. Arbuscular mycorrhizal fungi were spread on the upper surface of the propagation matrix. Then the disinfected red clover seeds were spread on the upper surface of the propagation matrix. Finally, a layer of propagation matrix was covered until the volume ratio of the matrix to arbuscular mycorrhizal fungi was 9:1. The matrix was moistened and propagated at 28°C and 15h / d of light for 30 days. The aboveground plant body was removed. The root segments in the propagation matrix were harvested after drying in the shade and crushed through a 2mm sieve to obtain an arbuscular mycorrhizal fungal spore mixture.

[0032] Preparation Example 1.2 The method for preparing the arbuscular mycorrhizal fungal spore mixture comprises the following steps: First, the red clover seeds were disinfected with 3% hydrogen peroxide for 5 minutes and then the propagation matrix was sterilized at 121°C for 1 hour. The propagation matrix included red soil and river sand in a ratio of 1:1. 2 / 3 of the sterilized propagation matrix was filled in the propagation container. Arbuscular mycorrhizal fungi were spread on the upper surface of the propagation matrix. Then the disinfected red clover seeds were spread on the upper surface of the propagation matrix. Finally, a layer of propagation matrix was covered until the volume ratio of the matrix to the arbuscular mycorrhizal fungi was 9:1. The matrix was moistened and propagated at 23°C and 16h / d of light for 30 days. The aboveground plant body was removed. The root segments in the propagation matrix were harvested after drying in the shade and crushed through a 2mm sieve to obtain an arbuscular mycorrhizal fungal spore mixture.

[0033] Preparation Example 1.3 The method for preparing the arbuscular mycorrhizal fungal spore mixture comprises the following steps: First, the red clover seeds were disinfected with 3% hydrogen peroxide for 5 minutes and then the propagation matrix was sterilized at 121°C for 1 hour. The propagation matrix included red soil and river sand in a ratio of 1:1. 2 / 3 of the sterilized propagation matrix was filled in the propagation container. Arbuscular mycorrhizal fungi were spread on the upper surface of the propagation matrix. Then the disinfected red clover seeds were spread on the upper surface of the propagation matrix. Finally, a layer of propagation matrix was covered until the volume ratio of the matrix to arbuscular mycorrhizal fungi was 9:1. The matrix was moistened and propagated at 25°C and 15.5h / d of light for 30 days. The aboveground plant body was removed and the root segments in the propagation matrix were harvested after drying in the shade and crushed through a 2mm sieve to obtain an arbuscular mycorrhizal fungal spore mixture.

[0034] Preparation Example 2 The method for preparing acidic biochar comprises the following steps: Ordinary biochar and 25wt% phosphoric acid solution were mixed evenly in a weight ratio of 1:2, allowed to stand for more than 30min, filtered, and the solid was washed until the pH of the eluate was constant, dried, ground, and passed through a 2mm sieve to obtain acid-modified biochar.

[0035] Example 1.1 A method for preparing a salt-alkali resistant composite bacterial agent comprises the following steps: S1. Preparation of bacterial solution: Enterobacter Ludwigii was cultured in the first stage and inoculated to obtain an effective viable bacterial count of 1×10 8 CFU / mL of growth-promoting bacteria solution for later use; S2. Carrier preparation: the matrix (1:2 ordinary biochar and diatomaceous earth) was dried, crushed through a 60-mesh sieve, and sterilized at 120°C for 30 minutes to obtain the carrier for later use; S3. Mixed fermentation: The growth-promoting bacterial liquid obtained in step S1 is blended with the carrier obtained in step S2, and then the arbuscular mycorrhizal fungal spore mixture prepared in Preparation Example 1.1 and nutrients (ammonium nitrate, potassium chloride and apatite in a ratio of 1:1:1) are added, with specific amounts as shown in Table 1. The mixture is fermented at 45°C for 12 hours, granulated and passed through a 1.0 mm sieve, and dried to a constant weight to obtain a salt-alkali resistant composite bacterial agent.

[0036] Example 1.2 A method for preparing a salt-alkali resistant composite bacterial agent comprises the following steps: S1. Preparation of bacterial solution: Serratia marcescens was cultured in the first stage and inoculated to obtain an effective viable bacterial count of 0.9×10 8 CFU / mL of growth-promoting bacteria solution for later use; S2. Carrier preparation: the matrix (2:1 ordinary biochar and diatomaceous earth) was dried, crushed through a 60-mesh sieve, and sterilized at 120°C for 30 minutes to obtain the carrier for later use; S3. Mixed fermentation: blend the growth-promoting bacterial liquid obtained in step S1 with the carrier obtained in step S2, and then add the arbuscular mycorrhizal fungal spore mixture and nutrients (ammonium nitrate, potassium chloride and apatite in a ratio of 1:1:1) prepared in Preparation Example 1.2, with specific amounts as shown in Table 1. Ferment at 45°C for 12h, granulate through a 0.6mm sieve, and dry to a constant weight to obtain a salt-alkali resistant composite bacterial agent.

[0037] Example 1.3 A method for preparing a salt-alkali resistant composite bacterial agent comprises the following steps: S1. Preparation of bacterial solution: The fecal alcaligenes was cultured in the first stage and inoculated, and the effective viable bacterial count was 0.8×10 8 CFU / mL of growth-promoting bacteria solution for later use; S2. Carrier preparation: the matrix (1:1 ordinary biochar and diatomaceous earth) was dried, crushed through a 60-mesh sieve, and sterilized at 120°C for 30 minutes to obtain the carrier for later use; S3. Mixed fermentation: blend the growth-promoting bacterial liquid obtained in step S1 with the carrier obtained in step S2, and then add the arbuscular mycorrhizal fungal spore mixture and nutrients (ammonium nitrate, potassium chloride and apatite in a ratio of 1:1:1) prepared in Preparation Example 1.3, with specific amounts as shown in Table 1. Ferment at 45°C for 12h, granulate through a 0.5mm sieve, and dry to a constant weight to obtain a salt-alkali resistant composite bacterial agent.

[0038] Table 1 Amount of each component used in Examples 1.1-1.3 / kg

[0039] Examples 2.1-2.8

[0040] A method for preparing a salt-alkali resistant composite bacterial agent, which is different from Example 1.1 in that the Ludwig Escherichia coli in step S1 is replaced. The specific replacement species and the number of viable bacteria in the growth-promoting bacterial liquid are shown in Table 2, and the rest are the same as Example 1.1.

[0041] Table 2 Specific replacement species of bacteria in Examples 2.1-2.8 and the number of viable bacteria in the growth-promoting bacterial solution

[0042] Examples 3.1-3.5

[0043] A method for preparing a salt-alkali resistant composite bacterial agent, which is different from that of Example 1.1 in that the components of the matrix in step S2 are different, as shown in Table 3, and the rest are the same as those of Example 1.1.

[0044] Table 3 Components of the matrix of Examples 3.1-3.5

[0045] Example 4.1 A method for preparing a salt-alkali resistant composite bacterial agent, which is different from Example 1.1 in that a dispersing agent is also added in step S3, specifically: the growth-promoting bacterial liquid obtained in step S1 is blended with the carrier obtained in step S2, and then 13 kg of dispersing agent (6:6:5 SDBS, CMC and ammonium sulfate) is added to prepare the arbuscular mycorrhizal fungal spore mixture and nutrients (1:1:1 ammonium nitrate, potassium chloride and apatite) obtained in Example 1.1, fermented at 45°C for 12 hours, granulated through a 1.0 mm sieve, and dried to a constant weight of the system to obtain a salt-alkali resistant composite bacterial agent.

[0046] Example 4.2 A method for preparing a salt-alkali resistant composite bacterial agent, which is different from Example 1.1 in that a dispersing agent is also added in step S3, specifically: the growth-promoting bacterial liquid obtained in step S1 is blended with the carrier obtained in step S2, and then 14 kg of a dispersing agent (7:6:4.5 SDBS, CMC and ammonium sulfate) is added to prepare the arbuscular mycorrhizal fungal spore mixture obtained in Example 1.1 and nutrients (1:1:1 ammonium nitrate, potassium chloride and apatite), fermented at 45°C for 12 hours, granulated through a 1.0 mm sieve, and dried to a constant weight of the system to obtain a salt-alkali resistant composite bacterial agent.

[0047] Example 4.3 A method for preparing a salt-alkali resistant composite bacterial agent, which is different from Example 1.1 in that a dispersing agent is also added in step S3, specifically: the growth-promoting bacterial liquid obtained in step S1 is blended with the carrier obtained in step S2, and then 15 kg of a dispersing agent (SDBS, CMC and ammonium sulfate in a ratio of 8:6:4) is added to prepare the arbuscular mycorrhizal fungal spore mixture obtained in Example 1.1 and nutrients (ammonium nitrate, potassium chloride and apatite in a ratio of 1:1:1), fermented at 45°C for 12 hours, granulated through a 1.0 mm sieve, and dried to a constant weight of the system to obtain a salt-alkali resistant composite bacterial agent.

[0048] Example 4.4 A method for preparing a salt-alkali resistant composite bacterial agent, which is different from Example 1.1 in that a dispersing agent is also added in step S3, specifically: the growth-promoting bacterial liquid obtained in step S1 is blended with the carrier obtained in step S2, and then 13 kg of a dispersing agent (6:6 SDBS, CMC) is added to prepare the arbuscular mycorrhizal fungal spore mixture obtained in Example 1.1 and nutrients (1:1:1 ammonium nitrate, potassium chloride and apatite), fermented at 45°C for 12 hours, granulated through a 1.0 mm sieve, and dried to a constant weight of the system to obtain a salt-alkali resistant composite bacterial agent.

[0049] Example 4.5 A method for preparing a salt-alkali resistant composite bacterial agent, which is different from Example 1.1 in that a dispersing agent is also added in step S3, specifically: the growth-promoting bacterial liquid obtained in step S1 is blended with the carrier obtained in step S2, and then 13 kg of a dispersing agent (6:5 CMC and ammonium sulfate) is added to prepare the arbuscular mycorrhizal fungal spore mixture obtained in Example 1.1 and nutrients (1:1:1 ammonium nitrate, potassium chloride and apatite), fermented at 45°C for 12 hours, granulated through a 1.0 mm sieve, and dried to a constant weight of the system to obtain a salt-alkali resistant composite bacterial agent.

[0050] Example 4.6 A method for preparing a salt-alkali resistant composite bacterial agent, which is different from Example 1.1 in that a dispersing agent is also added in step S3, specifically: the growth-promoting bacterial liquid obtained in step S1 is blended with the carrier obtained in step S2, and then 13 kg of a dispersing agent (6:5 SDBS, ammonium sulfate) is added to prepare the arbuscular mycorrhizal fungal spore mixture obtained in Example 1.1 and nutrients (1:1:1 ammonium nitrate, potassium chloride and apatite), fermented at 45°C for 12 hours, granulated through a 1.0 mm sieve, and dried to a constant weight of the system to obtain a salt-alkali resistant composite bacterial agent.

[0051] Examples 5.1-5.2 A method for preparing a salt-alkali resistant composite bacterial agent is different from that of Example 1.1 in that the granulation in step S3 is passed through a 0.6 mm sieve and a 0.8 mm sieve respectively, and the rest is the same as that of Example 1.1.

[0052] Comparative Examples 1.1-1.2 The difference from Example 1.1 is that in step S1, Enterobacter ludwigii is replaced by Bacillus subtilis and Acinetobacter beijerinii, respectively, and the rest is the same as Example 1.1.

[0053] Comparative Example 2 The difference from Example 1.1 is that in step S1, the arbuscular mycorrhizal fungal spore mixture prepared in Preparation Example 1.1 is removed, and the rest is the same as Example 1.1.

[0054] Comparative Examples 3.1-3.2 The difference from Example 1.1 is that in step S1, the effective viable bacteria counts of the growth-promoting bacteria solution are 0.5×10 8 CFU / mL and 1.5×10 8 CFU / mL, and the rest are the same as in Example 1.1.

[0055] Comparative Examples 4.1-4.5 The difference from Example 1.1 is that the matrix in step S2 is different, namely ordinary biochar, diatomaceous earth, 1:1 ordinary biochar and acidic biochar prepared in Preparation Example 1.1, 1:1 diatomaceous earth and acidic biochar prepared in Preparation Example 1.1, and 1:1 talcum powder and calcium carbonate, and the rest are the same as Example 1.1.

[0056] Comparative Example 5 The difference from Example 1.1 is that in step S3, after fermentation, granulation and screening are not performed but drying is performed directly. The rest is the same as Example 1.1.

[0057] Performance Testing The salt-alkali resistant composite bacterial agent prepared in the examples and comparative examples was heated at 3 kg / hm 2The application amount was applied to the saline-alkali soil, and the soil was turned over 30cm to make the salt-alkali tolerant composite bacterial agent and the saline-alkali soil evenly mixed. After 60 days of planting Suaeda salsa, the saline-alkali soil indicators (pH and organic matter content) and plant survival rate were measured and recorded in Table 4. The blank group was the saline-alkali soil without the addition of the salt-alkali tolerant composite bacterial agent. Note that in the performance test, this application only used 3kg / hm 2 The application amount is recorded because it has been determined by technicians that the application amount has little difference in the improvement effect on saline-alkali soil within the protection scope of this application, so only the midpoint value of the application amount is taken for illustration.

[0058] Table 4 Performance test table

[0059] Data Analysis: As can be seen from Table 1, the salt-alkali tolerant composite bacterial agent of Examples 1.1-1.3 of the present application can reduce the pH of saline-alkali soil to 7.62-7.64, increase the organic matter content to 0.82-0.85%, and increase the plant survival rate to 82.5-84.0%, proving that the arbuscular mycorrhizal fungal spore mixture, growth-promoting bacterial solution, matrix and nutrients of the present application can be mixed in a certain way to produce a salt-alkali tolerant composite bacterial agent with high survival rate and high activity, which greatly improves the improvement effect of saline-alkali soil; In Example 2, the present application changed the strains of growth-promoting bacteria and the ratio of each strain. The pH of Example 2.3 was 7.53, the organic matter content reached 0.90%, and the plant survival rate reached 87.2%, proving that the present application used a combination of Serratia marcescens and Alcaligenes faecalis with a certain effective live bacteria number ratio as the strains in the growth-promoting bacteria solution. The growth-promoting effect between the two bacteria was significantly better than other combinations, which can greatly improve the situation of saline-alkali soil; Examples 2.5-2.8 changed the ratio of the effective viable counts of Serratia marcescens and Alcaligenes faecalis. In Example 2.6, the pH was 7.45, the organic matter content reached 1.06%, and the plant survival rate reached 89.5%, proving that the synergistic effect of the two can be maximized under this ratio, increasing the organic matter content by 165% and the plant survival rate by 198%. In Example 3, the components of the substrate in step S2 are changed. Compared with Example 1.1, the pH is significantly reduced, and the organic matter content and plant survival rate are also improved. This proves that the application adds a certain amount of acidic biochar to the substrate, so that the salt-alkali tolerant composite bacterial agent has a certain ability to promote water infiltration when used, and at the same time makes the salt-alkali tolerant composite bacterial agent more tightly combined with the soil, thereby enhancing the water absorption and water retention of the soil, thereby increasing the water content near the roots of the plants, thereby improving the survival rate of the plants; The organic matter content and plant survival rate of Example 3.3 were as high as 0.94% and 89.4%, respectively, proving that the present application further improved the plant survival rate by controlling the amount of acidic biochar added. If the amount added was too little, it would not effectively promote water infiltration; if the amount added was too much, it would absorb water beyond the plant's needs into the soil at the roots of the plants, which would cause the plants to be subjected to abiotic stress from water, thereby reducing the plant survival rate and the organic matter content in the soil. In Example 4, a dispersing agent was added. Compared with Example 1.1, the pH was significantly reduced, and the organic matter content and plant survival rate were also improved, which proved that the present invention At the same time, the various indicators of Examples 4.1-4.3 are significantly better than those of Examples 4.4-4.6, proving that the present application greatly improves the dispersion and penetration ability of the salt-alkali tolerant composite bacterial agent in the soil by adding a dispersing aid, so that it can more efficiently improve the saline-alkali soil conditions, thereby further improving the organic matter content of the saline-alkali soil and the survival rate of plants; In Example 5, the sieve hole size in step S3 was changed, and the various indicators of Example 5.2 were significantly better than those of Example 1.1 and Example 5.1, proving that there was a synergistic effect between SDBS, CMC and ammonium sulfate, which could work together to improve the dispersion and penetration ability of the salt-alkali resistant composite bacterial agent in the soil; All indicators of comparative examples 1-4 are far inferior to those of example 1.1, proving that the present application utilizes a mixture of arbuscular mycorrhizal fungi spores and a compound of a growth-promoting bacterial solution to achieve a synergistic effect, thereby significantly promoting the absorption of nutrients by plants and improving the permeability of mycelium of plant roots. The effect is particularly evident in saline-alkali soils, which can protect plant pathogens and reduce the abiotic stress of salt and heavy metals on plants, thereby promoting efficient recycling of nutrients in saline-alkali soils, and rapidly restoring the fertility of saline-alkali soils, thereby greatly improving the organic matter content of saline-alkali soils and the survival rate of plants. The growth-promoting bacteria of the present application have a better synergistic effect with the mixture of arbuscular mycorrhizal fungi spores than other growth-promoting bacteria (Bacillus subtilis and Acinetobacter beijerinii). Within the same treatment time, the organic matter content of saline-alkali soils and the survival rate of plants can be greatly improved. It also proves that diatomaceous earth and ordinary biochar have good synergy, and the effect is significantly better than other carrier substances. Even if acidic biochar is added to diatomaceous earth and ordinary biochar respectively, it still cannot play an effective auxiliary role. All indicators of Comparative Example 5 are inferior to those of Example 1.1, which proves that the preparation method of the present application includes granulation and screening treatment, and the obtained salt-alkali resistant composite bacterial agent has higher dispersibility, stability and environmental friendliness than the existing powdered composite bacterial agent without granulation.

[0060] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A salt-alkali resistant composite bacterial agent, characterized in that: The raw materials used include the following components in parts by weight: 15-20 parts of arbuscular mycorrhizal fungal spore mixture; 20-25 parts of growth-promoting bacteria liquid; 60-70 parts of matrix; 4-5 parts of nutrients; 1-2 parts of trace elements, the bacterial species in the growth-promoting bacteria liquid include one or more of Enterobacter ludwigii, Serratia marcescens and Alcaligenes faecalis, and the matrix includes ordinary biochar and diatomaceous earth.

2. A salt-alkali resistant composite bacterial agent according to claim 1, characterized in that: The bacterial species in the growth-promoting bacterial liquid include Serratia marcescens and Alcaligenes faecalis with an effective live bacterial count ratio of (2-3):1.

5.

3. A salt-alkali resistant composite bacterial agent according to claim 2, characterized in that: The effective live bacterial count ratio of Serratia marcescens to Alcaligenes faecalis is 2.8:1.

5.

4. The salt-alkali resistant composite bacterial agent according to claim 1, characterized in that: The matrix also includes acidic biochar added in an amount of 2-8wt% of the total amount of the matrix.

5. A salt-alkali resistant composite bacterial agent according to claim 4, characterized in that: The amount of acidic biochar added is 5wt% of the total amount of the matrix.

6. The salt-alkali resistant composite bacterial agent according to claim 1, characterized in that: The raw materials used also include 13-15 parts by weight of a dispersing aid, which includes SDBS, CMC and ammonium sulfate in a weight ratio of (6-8):6:(4-5).

7. A method for preparing the salt-alkali resistant composite bacterial agent according to claim 1, characterized in that: The following steps are involved: S1. Preparation of bacterial solution: The growth-promoting bacteria were cultured in the first stage and inoculated to obtain an effective viable bacterial count of 0.8×10 8 CFU / mL-1×10 8 CFU / mL of growth-promoting bacteria solution for later use; S2, carrier preparation: drying the matrix, crushing and sieving, sterilizing to obtain the carrier for later use; S3, mixed fermentation: the growth-promoting bacterial liquid obtained in step S1 is mixed with the carrier obtained in step S2, and then the arbuscular mycorrhizal fungal spore mixture and nutrients are added, fermented, granulated and passed through a 0.5-1.0 mm sieve, and dried to a constant weight of the system to obtain a salt-alkali resistant composite bacterial agent.

8. The method for preparing the salt-alkali resistant composite bacterial agent according to claim 7, characterized in that: In the step S3, the granulated product is sieved through a 0.8 mm sieve.

9. The method for preparing the salt-alkali resistant composite bacterial agent according to claim 7, characterized in that: In the step S3, when the growth-promoting bacteria solution, the carrier, the arbuscular mycorrhizal fungal spore mixture and the nutrient substance are mixed, a dispersing aid is also added.

10. An application of a salt-alkali resistant composite bacterial agent, characterized in that: The application amount of the salt-alkali resistant composite bacterial agent is 2-4 kg / hm 2 .

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