Salt-alkali tolerant Bacillus pumilus and its application in saline-alkali land improvement

Abstract

The present invention belongs to the technical field of microorganisms and soil improvement, and specifically relates to salt-alkali tolerant Bacillus pumilus and its application in saline-alkali land improvement. The present invention uses biochar, humified agricultural and animal husbandry waste and salt-alkali tolerant microorganisms to improve saline-alkali soil. Compared with the method of using humified agricultural and animal husbandry waste or biochar alone to improve saline-alkali land, it not only has a better soil improvement effect, but also can promote the growth of various crops including corn by planting crops on the improved saline-alkali land. Furthermore, the salt-alkali tolerant and growth-promoting Bacillus pumilus L13 obtained by the present invention is applied to the above-mentioned saline-alkali land improvement method, and the saline-alkali land improvement effect is better.

Description

Technical Field

[0001] The invention belongs to the technical field of microorganisms and soil improvement, and particularly relates to salt-alkali tolerant Bacillus pumilus and application thereof in saline-alkali land improvement. Background Art

[0002] Soil salinization, caused by high salinity, high pH, ​​poor aeration, and nutrient deficiencies, significantly reduces agricultural productivity. Numerous remediation technologies, including substrate drainage, chemical precipitation, and adsorption, have been developed to address soil salinization, but their sustainability is often limited by cost, effectiveness, and potential for secondary pollution.

[0003] The application of biochar-based salt- and alkali-tolerant microorganisms is considered an effective method for improving saline-alkali soils. Biochar, a product produced by the pyrolysis of biomass under high-temperature, oxygen-limited conditions, is porous and rich in functional groups. It provides a porous habitat for salt- and alkali-tolerant microorganisms, strengthens soil structure, and accelerates salt loss. Some existing studies have proposed methods for the synergistic remediation of saline-alkali soils using biochar and microorganisms. However, biochar often contains inorganic components such as CaO, MgO, and CaCO3, which exhibit alkalinity. Direct application in saline-alkali soils carries the risk of secondary alkalinization. Furthermore, despite the wide variety of salt- and alkali-tolerant microorganisms and existing research on soil improvement using these microorganisms, some salt- and alkali-tolerant microorganisms are currently ineffective in improving soil salinization. The main reasons are: first, the low survival rate of the strains in saline-alkali soils and second, the strains' inherent salt- and alkali-tolerant properties and growth-promoting abilities are limited.

[0004] Biochar combined with the acidic substance humic acid has also become an important research focus in salinized soil remediation. Several studies have proposed methods for remediating salinized soils using biochar and humic acid. Furthermore, some studies have proposed using materials such as biochar and humic acid in conjunction with microbial agents to remediate salinized soils. However, as humic acid must be extracted from natural soil, peat, or other organic materials, its application is limited by complex extraction processes and high costs. Summary of the Invention

[0005] The present invention aims to provide salt-alkali tolerant Bacillus pumilus and its application in saline-alkali land improvement. The salt-alkali tolerant Bacillus pumilus has a significant improvement effect on saline-alkali land in collaboration with biochar and humified agricultural and animal husbandry waste.

[0006] The present invention provides a method for improving saline-alkali land, comprising the following steps:

[0007] mixing biochar, humified agricultural and animal husbandry waste and saline-alkali soil to obtain mixed saline-alkali soil;

[0008] Salt-alkali tolerant microorganisms are applied to the mixed saline-alkali soil for mixed cultivation to obtain improved saline-alkali land.

[0009] Preferably, the amount of biochar used is 1.44-2.40 tons per mu of saline-alkali land; the amount of humified agricultural and animal husbandry waste used is 7.67-11.51 tons per mu of saline-alkali land; the amount of salt-alkali tolerant microorganisms used is calculated based on the salt-alkali tolerant microorganism liquid, the mass ratio of the volume of the salt-alkali tolerant microorganism liquid to the saline-alkali soil is 1-2 mL: 10-20 g, and the effective concentration of the salt-alkali tolerant microorganism liquid is 1×10 8 CFU / mL.

[0010] Preferably, the biochar comprises crop straw biochar; and the preparation step of the crop straw biochar comprises: calcining the crop straw at 450-500° C. for 1.5-2 h to obtain the crop straw biochar.

[0011] Preferably, the step of preparing the humified agricultural and animal husbandry waste comprises: mixing animal feces, crop straw and mature bacterial strains and then composting them until they are mature, thereby obtaining the humified agricultural and animal husbandry waste;

[0012] The decomposing strains include Acetobacter and Pichia pastoris, the volume ratio of Acetobacter to Pichia pastoris is 1-2:1-2, and the effective live bacterial concentrations of Acetobacter and Pichia pastoris are both (0.5-1)×10 8 CFU / mL; the inoculation amount of the bacterial solution of the mature strain is 15% to 20% (v / m) of the total dry matter of the animal feces and crop straw;

[0013] The dry matter mass ratio of the animal feces to the crop straw is 1:1-2.

[0014] Preferably, the mixed culture time is 15 to 20 days.

[0015] Preferably, the salt-alkali tolerant microorganisms include Bacillus pumilus ( Bacillus pumilus ).

[0016] Preferably, the Bacillus pumilus includes Bacillus pumilus L13, and the deposit number of the Bacillus pumilus L13 is CGMCC No.32044.

[0017] The present invention also provides the application of the saline-alkali land improvement method described in the above technical solution in promoting crop growth.

[0018] The present invention provides a Bacillus pumilus L13 strain, and the deposit number of the Bacillus pumilus L13 is CGMCC No.32044.

[0019] The present invention also provides the use of the Bacillus pumilus L13 described in the above technical solution in soil improvement and / or promoting plant growth.

[0020] Beneficial effects:

[0021] The present invention provides a method for improving saline-alkali land, comprising the steps of: mixing biochar, humified agricultural and animal husbandry waste, and saline-alkali soil to obtain mixed saline-alkali soil; and applying salt-alkali-tolerant microorganisms to the mixed saline-alkali soil for mixed cultivation to obtain improved saline-alkali land. The present invention utilizes biochar, humified agricultural and animal husbandry waste, and salt-alkali-tolerant microorganisms for saline-alkali soil improvement. Compared to methods using humified agricultural and animal husbandry waste or biochar alone to improve saline-alkali land, the present invention not only achieves a more effective soil improvement effect, but also promotes the growth of various crops, including corn, by planting crops on the improved saline-alkali land.

[0022] Furthermore, the salt-alkali-tolerant and growth-promoting Bacillus pumilus L13 isolated and obtained by the present invention is applied to the above-mentioned saline-alkali land improvement method, and the saline-alkali land improvement effect is better.

[0023] Biological Deposits

[0024] Bacillus pumilus L13, biologically classified as Bacillus pumilus , deposited in the China General Microorganism Culture Collection (CGMCC) on September 23, 2024, with the culture collection number CGMCC No.32044, and the deposit address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, Postal Code 100101. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below.

[0026] Figure 1 The results of the screening of the salt- and alkali-tolerant strain L13 in Example 1 are as follows;

[0027] Figure 2 The results of the plant growth-promoting performance test of the salt-alkali tolerant strain L13 in Example 1 are as follows;

[0028] Figure 3 is the phylogenetic tree of Bacillus pumilus L13 in Example 1;

[0029] Figure 4 This is a colony image of Bacillus pumilus L13 in Example 1;

[0030] Figure 5 The effects of biochar, humified agricultural and animal husbandry waste materials and Bacillus pumilus on maize phenotype, plant height and biomass in Example 2;

[0031] Figure 6 The effects of biochar, humified agricultural and animal husbandry waste materials and Bacillus pumilus on the geochemical properties of saline-alkali land in Example 2;

[0032] Figure 7 This is the effect of biochar, humified agricultural and animal husbandry waste materials and Bacillus pumilus on the nutritional components of saline-alkali soil in Example 2. DETAILED DESCRIPTION

[0033] The present invention provides a method for improving saline-alkali land, comprising the following steps:

[0034] mixing biochar, humified agricultural and animal husbandry waste and saline-alkali soil to obtain mixed saline-alkali soil;

[0035] Salt-alkali tolerant microorganisms are applied to the mixed saline-alkali soil for mixed cultivation to obtain improved saline-alkali land.

[0036] In one embodiment, the present invention prepares biochar. In one embodiment, the biochar can be crop straw biochar. The preparation of the crop straw biochar comprises calcining the crop straw at 450-500°C for 1.5-2 hours to obtain the crop straw biochar. In one embodiment, the calcination temperature is 500°C for 2 hours. In one embodiment, the calcination is performed in a muffle furnace. In one embodiment, the crop straw includes but is not limited to corn straw.

[0037] In one embodiment, the present invention prepares humified agricultural and animal husbandry waste. The preparation step of the humified agricultural and animal husbandry waste comprises: mixing animal manure, crop straw, and a mature bacterial strain, then composting until mature, thereby obtaining the humified agricultural and animal husbandry waste. In one embodiment, the dry matter (water content is 0%, the same applies to dry matter below) mass ratio of the animal manure to the crop straw is 1:1-2; in another embodiment, the dry matter mass ratio of the animal manure to the crop straw is 1:2. In one embodiment, the animal manure includes but is not limited to sheep manure. In one embodiment, the inoculum size of the mature bacterial strain is 15%-20% of the total dry matter of the animal manure and crop straw; in another embodiment, the volume of the mature bacterial strain is 20% (v / m = mL / g) of the total dry matter of the animal manure and crop straw. In one embodiment, the decomposing strains are Acetobacter and Pichia pastoris, and the volume ratio of Acetobacter to Pichia pastoris is 1-2:1-2. In another embodiment, the volume ratio of Acetobacter to Pichia pastoris is 1:1, and the effective viable bacterial concentrations of Acetobacter and Pichia pastoris are (0.5-1)×10 8CFU / mL; As another embodiment, the effective viable bacterial concentrations of Acetobacter and Pichia are both 10 8 CFU / mL. As an embodiment, the Acetobacter described in the present invention may be Acetobacter aceti; the Pichia pastoris may be Pichia membranaceus. The advantage of using Acetobacter and Pichia pastoris as the composting strains in the present invention is that both have the ability to efficiently degrade organic matter, and the synergistic treatment of the two can also regulate the pH of the pile and increase the microbial diversity in the pile. As an embodiment, the composting time of the present invention is 45 to 60 days; as another embodiment, the composting time is 50 days. As an embodiment, the initial moisture content of the compost is 60% to 70%; as another embodiment, the initial moisture content of the compost is 65%. As an embodiment, the humified agricultural and animal husbandry waste described in the present invention has the advantages of high organic matter content, high effective nutrient content and rich in various beneficial microorganisms.

[0038] After obtaining the biochar and humified agricultural and animal husbandry waste, the present invention mixes the biochar, humified agricultural and animal husbandry waste, and saline-alkali soil to produce mixed saline-alkali soil. In one embodiment, the biochar is used in an amount of 1.44 to 2.40 tons per mu of saline-alkali land; in another embodiment, the biochar is used in an amount of 1.92 tons per mu of saline-alkali land. In one embodiment, the humified agricultural and animal husbandry waste is used in an amount of 7.67 to 11.51 tons per mu of saline-alkali land; in another embodiment, the humified agricultural and animal husbandry waste is used in an amount of 9.59 tons per mu of saline-alkali land. In one embodiment, the saline-alkali soil has a pH of 8.5 to 9.5 and a salt content of 5 to 7 g / kg.

[0039] After obtaining the mixed saline-alkali soil, the present invention applies salt-alkali-tolerant microorganisms to the mixed saline-alkali soil for mixed cultivation to obtain improved saline-alkali land. As an embodiment, the salt-alkali-tolerant microorganisms are sprayed into the mixed saline-alkali soil in the form of a salt-alkali-tolerant microbial liquid. As an embodiment, the amount of the salt-alkali-tolerant microorganisms used is calculated based on the salt-alkali-tolerant microbial liquid, and the mass ratio of the volume of the salt-alkali-tolerant microbial liquid to the saline-alkali soil is 1~2 mL:10~20 g; as another embodiment, the mass ratio of the volume of the salt-alkali-tolerant microbial liquid to the saline-alkali soil is 1 mL:10 g. As an embodiment, the effective concentration of the salt-alkali-tolerant microbial liquid is 1×10 8 CFU / mL. As an embodiment, the salt-alkali tolerant microorganism may be Bacillus pumilus ( Bacillus pumilusIn another embodiment, the Bacillus pumilus is Bacillus pumilus L13, the deposit number of which is CGMCC No. 32044. In one embodiment, the mixed culture can be carried out for 15 to 20 days. The Bacillus pumilus L13 described in the present invention is isolated from severely saline-alkali soil and has good salt-alkali tolerance, making it suitable for improving saline-alkali land.

[0040] The present invention uses biochar, humified agricultural and animal husbandry waste and salt-alkali tolerant microorganisms to synergistically improve saline-alkali soil. The synergistic effects of biochar, humified agricultural and animal husbandry waste and salt-alkali tolerant microorganisms have the effects of optimizing soil physical structure (reducing soil bulk density, increasing soil water holding capacity and total porosity) and improving soil fertility (increasing the content of effective nutrients such as alkaline-hydrolyzable nitrogen and available phosphorus), and have excellent improvement effects on saline-alkali soil.

[0041] The present invention also provides an application of the saline-alkali land improvement method described in the above technical solution in promoting crop growth. After the saline-alkali land is improved by the saline-alkali land improvement method described in the above technical solution of the present invention, crops are planted on the improved saline-alkali land to promote the growth of the crops.

[0042] The present invention provides a Bacillus pumilus L13 strain, and the deposit number of the Bacillus pumilus L13 is CGMCC No.32044.

[0043] The present invention also provides the use of the Bacillus pumilus L13 described in the above technical solution in soil improvement and / or plant growth promotion. As an embodiment, the soil improvement is saline-alkali land improvement.

[0044] In order to further illustrate the present invention, the technical solution provided by the present invention is described in detail below with reference to the accompanying drawings and embodiments, but they should not be construed as limiting the scope of protection of the present invention. Example

[0045] 1. Mix 5 g of heavily saline soil collected from Bayannur City, Inner Mongolia Autonomous Region with 45 mL of physiological saline solution and place in a 100 mL conical flask. Oscillate at 180 rpm at 28°C for 30 min. After standing for 5 min, collect the supernatant. Gradually dilute the supernatant according to the concentration gradient. Take 10 -1 , 10 -2 , 10 -3 and 10 -4 Spread 100 μL of the dilution onto beef extract peptone solid medium and incubate at 28°C for 48 h. Select strains with different morphologies and perform multiple purifications until a monoclonal strain is obtained.

[0046] When identifying the salt-alkali tolerance of the strain, beef extract peptone solid medium with NaCl concentrations of 2%, 8% and 14% and pH values ​​of 8, 9, 10, 11 and 12 was prepared respectively. The monoclonal strain was inoculated on the beef extract peptone solid medium and cultured at 28°C for 48 h. The naturally grown strain was used as a control. A highly salt-alkali tolerant strain that could grow in an environment with a salt concentration of 8% and a pH of 11 was screened out and named L13. Figure 1 L13 was prepared into bacterial liquid for plant growth promotion experiment.

[0047] 2. Preparation of bacterial solution: beef extract peptone liquid medium was used for propagation at 28°C. After 48 h of propagation, the bacteria were collected by centrifugation and the concentration of the bacterial solution was adjusted to 1×10 8 CFU / mL, and the bacterial solution was prepared.

[0048] Plant growth promotion experiment: Two-week-old corn plants were transplanted into pots (12.7 cm diameter, 9 cm bottom diameter, and 11 cm height) filled with 500 g of saline-alkali soil (salt content 6.37 g / kg, pH 9.05). The strain L13 was prepared into a bacterial solution according to the above-mentioned "Bacterial Solution Preparation" procedure. The treatment groups were designated as CK blank group and L13 group. The L13 treatment group was sprayed with 30 mL of bacterial solution every 7 days (10 8 CFU / mL), and the CK blank group was added with the same amount of water at the same time.

[0049] CK group: salinized soil, no addition of any substances;

[0050] L13 group: saline-alkali soil, only the bacterial solution prepared by L13 strain was added;

[0051] The above test was used to study the growth promotion of corn using L13. After 30 days, the growth promotion effect of L13 on corn was as follows: Figure 2 shown.

[0052] Depend on Figure 2 It can be concluded that in the same saline-alkali soil, the corn in the L13 group grew relatively better than that in the CK group, that is, it had a certain growth-promoting effect. The L13 strain was identified by whole genome sequencing (WGS).

[0053] 3. The L13 strain was sequenced and identified by whole genome sequencing, and the obtained sequencing data were compared in the NCBI database. The phylogenetic tree results are as follows: Figure 3 At the same time, the colony growth diagram of L13 strain grown in beef extract peptone solid medium for 48 hours is shown in Figure 4 shown.

[0054] Depend on Figure 3It can be concluded that the bootstrap value of the branch node of the L13 strain and Bacillus pumilus NDY-10 in the phylogenetic tree is 68, indicating that the two have a high degree of similarity (a bootstrap value greater than 50 is considered credible in microorganisms). It can be seen that the L13 strain and Bacillus pumilus NDY-10 sequences are highly homologous. At the same time, through comparison, it was found that the 16S rRNA hypervariable region gene sequence similarity is 100%. Figure 4 The colony was milky white, smooth, and had branched bacterial features. It was concluded that the strain L13 with growth-promoting ability was identified as Bacillus pumilus by WGS and phenotype. The strain was named Bacillus pumilus L13 and deposited in the China General Microbiological Culture Collection (CGMCC) with the culture collection number: CGMCC No. 32044.

[0055]

[0056] Example 2

[0057] A method for improving saline-alkali land comprises the following steps:

[0058] 1. Preparation of biochar

[0059] The air-dried corn straw was chopped into pieces of about 2 cm and pyrolyzed at 500 °C in a muffle furnace for 2 h. The prepared biochar was then ground and passed through a 100-mesh sieve to obtain corn straw biochar.

[0060] 2. Preparation of humified agricultural and animal husbandry waste

[0061] Sheep manure, crop straw, Acetobacter aceti (effective concentration 10 8 CFU / mL, purchased from China General Microbial Culture Collection Center, the strain name is Acetobacter aceti) and Pichia pastoris (effective concentration 10 8 CFU / mL, purchased from China General Microbial Culture Collection Center (CGMCC), the strain name is Pichia membranifuciens) after mixing, adjusting the initial moisture content of the compost system to 65%, and composting for 50 days. After complete decomposition, humified agricultural and animal husbandry waste was obtained;

[0062] The inoculation volume ratio of Acetobacter aceti and Pichia pastoris was 1:1, and the inoculation volume of the bacterial solution of the two bacteria was 20% (mL / g) of the total dry matter of the mixture of sheep manure and crop straw.

[0063] 3. The salinized soil in Hetao, Inner Mongolia Autonomous Region was improved, and five treatments were set up: CK blank group, SB group, SBM group, SH group and SHBM group to determine the improvement effect of each experimental group on the salinized soil; the salt content of the salinized soil was 6.37 g / kg and the pH value was 9.05. In each of the following treatment groups, the biochar was the biochar prepared in step 1; the humified agricultural and animal husbandry waste was prepared in step 2; the Bacillus pumilus liquid was the Bacillus pumilus L13 liquid, and the effective concentration was 10 8 CFU / mL. The percentage of each substance is calculated relative to salinized soil.

[0064] CK group: salinized soil, no addition of any substances;

[0065] SB group: saline-alkali soil, only 2% biochar added (w / w);

[0066] SBM group: saline-alkali soil, added with 2% biochar (w / w) and 10% Bacillus pumilus L13 solution (v / m=mL / g, concentration of 10 8CFU / mL);

[0067] SH group: saline-alkali soil, only 10% humified agricultural and animal husbandry waste was added (w / w);

[0068] SHBM group: saline-alkali soil, supplemented with 2% biochar (w / w), 10% humified agricultural and animal husbandry waste (w / w), and 10% Bacillus pumilus L13 solution (v / m = mL / g);

[0069] The above five groups of experiments were used to improve the Hetao saline-alkali land in Inner Mongolia Autonomous Region. Specifically, biochar, humified agricultural and animal husbandry waste were evenly mixed with saline-alkali soil, and then Bacillus pumilus L13 liquid was sprayed. After mixed cultivation for 15 days, corn was planted.

[0070] The phenotype of corn seedlings was observed from the time of germination to the 20th day of growth. After the 20th day of cultivation, the height of the aboveground and underground parts of the corn seedlings as well as the biomass such as fresh weight and dry weight of the plants were measured. Figure 5 As shown, in Figure 5 Different letters in B and C indicate significant differences P <0.05.

[0071] in accordance with Figure 5 The CK, SH and SHBM groups with large phenotypic differences and strong representativeness were selected to measure soil physical and chemical indicators (physical structure and chemical properties).

[0072] 4. Determination of soil physical and chemical indicators:

[0073] A portion of fresh soil samples was reserved for ammonium nitrogen (NH4 + -N) and nitrate nitrogen (NO3 - -N) content was determined, and the remaining soil samples were air-dried; a portion of the air-dried soil sample was ground and passed through a 100-mesh sieve, and the sieved sample was retained. Soil bulk density, soil mass water content, maximum water holding capacity (MWHC), capillary water holding capacity, minimum water holding capacity (WHC), non-capillary pores, capillary pores, and total pores were determined by the ring knife method; ammonium nitrogen (NH4 + -N) and nitrate nitrogen (NO3 --N) content; soil pH and electrical conductivity were measured using a pH meter (FE28, Mettler-Toledo, Switzerland) and an electrical conductivity (EC) meter (DDS-307, Shanghai, China) at a soil:water ratio of 1:5 (w / v); total salt content was determined gravimetrically; organic matter content was determined by potassium dichromate oxidation; total nitrogen (TN) was determined by the Kjeldahl method; total phosphorus (TP), total potassium (TK), and available potassium (AK) were determined by inductively coupled plasma mass spectrometry (AVIO 200, PerkinElmer, USA); available phosphorus (AP) was determined by sodium bicarbonate extraction-molybdenum antimony counterspectrophotometry; and alkaline-hydrolyzed nitrogen was determined by the alkali diffusion method. The experimental results are shown in the figure. Figures 6 and 7 As shown, in Figures 6 and 7 "*", "**" and "***" indicate significant differences P <0.05, P <0.01 and P <0.001; ns indicates no significant difference.

[0074] Depend on Figure 6 Compared with the CK treatment, the soil bulk density in the SH and SHBM treatments decreased by 6.73% and 11.85%, respectively. However, the mass water content (6.53% and 14.15%), MWHC (8.82% and 14.43%), capillary water holding capacity (9.23% and 14.78%), and WHC (6.53% and 14.15%) of both treatments increased significantly. Notably, the results of the combined SHBM treatment significantly exceeded those achieved by adding only humified agricultural and livestock waste. Furthermore, the SHBM treatment significantly increased soil capillary pores and total pores by 5.42% and 5.11%, respectively. This highlights the synergistic benefits of biochar, humified agricultural and livestock waste, and strain L13 in soil improvement. Compared with the CK-treated soil, the pH of the soil treated with SH and SHBM was significantly lower. Soil organic matter is an important indicator of soil quality and agricultural sustainability. Organic matter in the SH and SHBM groups increased by 0.63-fold and 2.04-fold, respectively, compared to the CK group. The SHBM group significantly increased soil organic matter to 30.40 g / kg, 0.87-fold that of the SH group. The EC and total salinity of the soils amended with SH and SHBM were not significantly different from those in the CK soil. Clearly, the significant growth of maize following the combined application of biochar, humified agricultural and animal husbandry waste, and strain L13 suggests that it may not be particularly advantageous in improving soil salinity, but rather superior in reducing soil pH and increasing soil organic matter.

[0075] Depend on Figure 7 It can be concluded that compared with the CK group and the SH group, the alkaline nitrogen content of the SHBM group increased by 3.32 times and 1.07 times, respectively, and NO3 --N content increased by 5.39 times and 4.82 times, NH4 + There were no significant differences in α-N content between all treatments. Furthermore, soil TN in the SHBM treatment also significantly increased by 0.66-fold and 0.15-fold compared to the CK and SH treatments. AP and AK in the SHBM group were 1.35-fold and 0.48-fold higher than in the CK group, and 0.20-fold and 0.14-fold higher than in the SH group, respectively. Simultaneously, TP and TK in the SHBM group were 0.31-fold and 0.43-fold lower than in the CK group, and 0.29-fold and 0.35-fold lower than in the SH group. This result suggests that TP and TK were more efficiently converted to AP and AK due to the synergistic effects of biochar, humified agricultural and livestock waste, and strain L13 in the soil. Clearly, AN, AP, and AK can be directly absorbed by plants, and biochar, humified agricultural and livestock waste, and strain L13 synergistically accelerated nutrient decomposition rates, as reflected in the highest growth of maize in the SHBM group.

[0076] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for improving saline-alkali land, characterized in that: The steps include: mixing biochar, humified agricultural and animal husbandry waste and saline-alkali soil to obtain mixed saline-alkali soil; applying salt-alkali tolerant microorganisms to the mixed saline-alkali soil for mixed cultivation to obtain improved saline-alkali land; The amount of biochar used is 1.44-2.40 tons per mu of saline-alkali land; the amount of humified agricultural and animal husbandry waste used is 7.67-11.51 tons per mu of saline-alkali land; the amount of salt-alkali tolerant microorganisms used is calculated based on the salt-alkali tolerant microorganism liquid, the mass ratio of the salt-alkali tolerant microorganism liquid to the saline-alkali soil is 1-2 mL: 10-20 g, and the effective concentration of the salt-alkali tolerant microorganism liquid is 1×10 8 CFU / mL; The salt-alkali tolerant microorganisms include Bacillus pumilus ( Bacillus pumilus ); The Bacillus pumilus includes Bacillus pumilus L13, and the deposit number of the Bacillus pumilus L13 is CGMCC No.32044.

2. The saline-alkali land improvement method according to claim 1, characterized in that: The biochar includes crop straw biochar; the preparation step of the crop straw biochar includes: calcining the crop straw at 450-500° C. for 1.5-2 h to obtain the crop straw biochar.

3. The saline-alkali land improvement method according to claim 1, characterized in that: The preparation steps of the humified agricultural and animal husbandry waste include: mixing animal feces, crop straw and mature bacterial strains and then composting them until they are mature, thereby obtaining the humified agricultural and animal husbandry waste; The decomposing strains include Acetobacter and Pichia pastoris, the volume ratio of Acetobacter to Pichia pastoris is 1-2:1-2, and the effective live bacterial concentrations of Acetobacter and Pichia pastoris are both (0.5-1)×10 8 CFU / mL; the inoculation amount of the bacterial solution of the mature strain is 15% to 20% v / m of the total dry matter of the animal feces and crop straw; The dry matter mass ratio of the animal feces to the crop straw is 1:1-2.

4. The saline-alkali land improvement method according to claim 1, characterized in that: The mixed culture time is 15 to 20 days.

5. Use of the saline-alkali land improvement method according to any one of claims 1 to 4 in promoting crop growth.

6. A strain of Bacillus pumilus L13, the deposit number of which is CGMCC No. 32044.

7. Use of the Bacillus pumilus L13 according to claim 6 in soil improvement and / or plant growth promotion.

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