A biological type saline-alkali soil conditioner as well as a preparation method and application thereof

Abstract

The application relates to a biological saline-alkali soil conditioner as well as a preparation method and application thereof, and belongs to the technical field of microorganisms. In order to solve the problems of low activity, single function and poor aggregation promotion effect of an existing biological conditioner in a low-temperature saline-alkali environment of black soil in a cold region, the application provides a biological saline-alkali soil conditioner which comprises a multifunctional composite bacterial system Z2 composed of bacillus velezensis PZ-3, bacillus cereus K1, streptomyces microflavus CLSD-1 and pseudomonas alcaliphila WP9, and a carrier matrix auxiliary material composed of chitosan, polyacrylamide and biogas residue. The biological saline-alkali soil conditioner provided by the application has multiple functions of low-temperature saline-alkali resistance, yield increase, straw degradation and aggregation body formation, can effectively reduce the soil pH and bulk density, improve the aggregation body proportion and moisture content, significantly promote crop growth and increase yield, is suitable for the improvement of black soil and low-temperature saline-alkali soil in the northeast cold region, and is environment-friendly and free of chemical residues.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology, and in particular relates to a biological saline-alkali soil conditioner, its preparation method, and its application. Background Technology

[0002] Black soil, as the most fertile soil type in the world, possesses extremely high fertility and is suitable for agricultural production. Northeast China, as one of the world's four major black soil distribution areas, plays a decisive role in my country's agricultural productivity. However, in recent years, the Northeast region has been severely affected by natural factors such as low average annual temperatures, drought, and severe salinization in some areas, which have seriously constrained crop yields and the sustainable development of agriculture.

[0003] Currently, most soil conditioners on the market are chemical-based, which pose significant environmental risks, poor adaptability, and substantial disturbance to soil microbial communities. This highlights the urgent need for biological soil conditioners in black soil conservation. Biological soil conditioners improve soil structure and fertility and promote plant growth through the action of microorganisms and organic matter, making them an important tool for promoting sustainable agriculture. However, existing products exhibit low activity in low-temperature, saline-alkali environments, have limited functionality, and show little effect in promoting soil aggregation, making it difficult to meet the actual needs of black soil improvement in cold regions.

[0004] The unique environmental conditions of Northeast China, coupled with the lack of low-temperature resistant, saline-alkali-tolerant, and aggregate-promoting biological soil conditioners, compel us to focus on the scientific issues of the combined promotion of soil aggregate formation by microorganisms and carriers, and the mitigation of soil salinization, in order to break through the production and application technologies of biological soil conditioners. Therefore, those skilled in the art are eager to develop a novel biological soil conditioner that is resistant to low temperatures, alleviates soil salinization, increases yield, promotes soil aggregate formation, facilitates straw degradation, and improves soil fertility. Summary of the Invention

[0005] This invention addresses the problems of low activity, limited functionality, and poor aggregation promotion effect of existing biological conditioners in cold black soil environments, by providing a biological saline-alkali soil conditioner, its preparation method, and its application.

[0006] One of the objectives of this invention is to provide a biological saline-alkali soil conditioner, which is obtained by mixing a multifunctional composite microbial strain Z2 and a carrier matrix excipient in a mass ratio of 1:(20-50).

[0007] In a preferred embodiment of the present invention, the multifunctional composite bacterial strain Z2 is composed of Bacillus belysinus (B. belysinus). Bacillus velezensis PZ-3, Bacillus cereus ( Bacillus cereus K1, Streptomyces flavus ( Streptomyces microflavus CLSD-1 and basophilic pseudomonas ( Pseudomonas alcaliphila It consists of WP9.

[0008] In a preferred embodiment of the present invention, the mixed mass ratio of Bacillus belyssus PZ-3, Bacillus cereus K1, Streptomyces flavus CLSD-1 and Pseudomonas alkalophilus WP9 in the multifunctional composite bacterial system Z2 is (0.8-1.2):(0.8-1.2):(0.8-1.2):(0.8-1.2).

[0009] In a preferred embodiment of the present invention, the Bacillus belyssus PZ-3 has the accession number CCTCC NO: M20231826, the Bacillus cereus K1 has the accession number CCTCC NO: M 2026655, the Streptomyces flavus CLSD-1 has the accession number CCTCC NO: M 2023664, and the Pseudomonas basophila WP9 has the accession number CCTCC NO: M 2026656.

[0010] In a preferred embodiment of the present invention, the carrier matrix excipient is composed of the following components, in parts by weight: 1-2 parts chitosan, 2-4 parts polyacrylamide, and 94-97 parts biogas residue.

[0011] A second objective of this invention is to provide a method for preparing the aforementioned biological saline-alkali soil conditioner, the method comprising the following steps: S1: Composite bacterial culture: Bacillus belye PZ-3, Bacillus cereus K1, Streptomyces flavus CLSD-1 and Pseudomonas alkalophilus WP9 were combined in a certain mass ratio to obtain a multifunctional composite bacterial culture Z2; S2: Carrier matrix excipient premixing: Chitosan, polyacrylamide and biogas residue are premixed to obtain carrier matrix excipients; S3: Conditioner preparation: Mix the multifunctional composite microbial system Z2 obtained in S1 with the carrier matrix excipient obtained in S2 evenly to obtain a biological saline-alkali soil conditioner.

[0012] The third objective of this invention is to provide the application of the above-mentioned biological saline-alkali soil conditioner in improving saline-alkali soil.

[0013] In a preferred embodiment of the present invention, the biological saline-alkali soil conditioner has at least one of the following functions (1)-(7): (1) It maintains its activity in saline-alkali soil environments with temperatures ranging from 0 to 15℃ and pH values ​​from 7.5 to 9.5; (2) Lower soil pH; (3) Increase soil moisture content; (4) Improve soil physical and chemical properties; (5) Degrading straw; (6) Promotes aggregate formation; (7) Increase crop yield.

[0014] In a preferred embodiment of the present invention, the amount of biological saline-alkali soil conditioner used in the application is 50-100 kg per acre.

[0015] In a preferred embodiment of the present invention, the method of using the biological saline-alkali soil conditioner is as follows: the biological saline-alkali soil conditioner is applied simultaneously with the seeds at the time of sowing.

[0016] Compared with the prior art, the beneficial effects of the present invention are: the present invention provides a biological saline-alkali soil conditioner, which is obtained by mixing a multifunctional composite bacterial system Z2 (Bacillus belye PZ-3, Bacillus cereus K1, Streptomyces flavus CLSD-1 and Pseudomonas alkalophilus WP9) and a carrier matrix excipient (chitosan, polyacrylamide and biogas residue).

[0017] This invention is the first to combine four functional bacteria—Bacillus belye PZ-3, Bacillus cereus K1, Streptomyces flavus CLSD-1, and Pseudomonas alkalophilus WP9—in a compound formulation. Through the synergistic effect among these strains, it achieves the goals of producing polyglutamic acid, promoting soil aggregation, degrading straw, improving soil microecology, and adapting to saline-alkali environments. The yield increase is significant, with field trials showing a 23.0% increase in corn yield. The multifunctional compound bacterial system maintains high activity under conditions of 0-15℃ and pH 7.5-9.5, breaking through the technical bottleneck of the rapid decline in activity of existing biological conditioners in cold, low-temperature, and saline-alkali environments. It achieves a multifunctional integration of "low-temperature resistance, salinity reduction, aggregation promotion, and straw degradation," rather than the single-function superposition of existing technologies.

[0018] This invention innovatively uses chitosan, polyacrylamide, and biogas residue as a composite carrier matrix to form a three-in-one system of "microorganisms-organic matter-porous structure". Chitosan provides a carbon source and promotes bacterial colonization, polyacrylamide enhances water retention and aggregation, and biogas residue is rich in organic nutrients, providing an organic carbon source to promote bacterial reproduction. The synergistic effect makes the soil improvement effect of the multifunctional composite microbial system significantly better than that of a single carrier or chemical carrier, effectively reducing soil pH and bulk density, and increasing the proportion of aggregates and water content.

[0019] This invention addresses the ecological protection needs of black soil regions by using all-bio-based raw materials, eliminating the risk of residual chemical synthetic components such as polyacrylamide. It combines the advantages of protecting the ecological environment with cost savings, overcoming the shortcomings of chemical conditioners, such as high environmental risks and disturbance of soil microbial communities, and aligns with the direction of green agricultural development.

[0020] This invention addresses the unique environmental conditions of Northeast China, characterized by low temperatures throughout the year and salinization in some areas. From strain selection and formulation to carrier design, the entire process revolves around the needs of improving black soil in cold regions. It fills the technological gap in low-temperature resistant, saline-alkali resistant, and aggregate-promoting biological soil conditioners, demonstrating significant scientific value and application prospects.

[0021] [Biological Preservation Information]: Bacillus cereus ( Bacillus cereus K1's accession number is CCTCC NO: M 2026655, and its classification is named as follows: Bacillus cereus It is deposited at the China Center for Type Culture Collection, dated April 13, 2026, at Wuhan University, Wuhan, China.

[0022] Basophilic Pseudomonas ( Pseudomonas alcaliphila WP9's accession number is CCTCC NO: M 2026656, and its classification is named as follows: Pseudomonas alcaliphila It is deposited at the China Center for Type Culture Collection on April 13, 2026, at Wuhan University, Wuhan, China. Attached Figure Description

[0023] Figure 1 This is a single colony morphology diagram of Pseudomonas basophilus WP9 in Example 1; Figure 2 This is the phylogenetic tree of basophilic Pseudomonas WP9 in Example 1; Figure 3 This is a single colony morphology diagram of Bacillus cereus K1 in Example 1; Figure 4 This is the phylogenetic tree of Bacillus cereus K1 in Example 1; Figure 5 The following are growth curves and pH change graphs of the multifunctional composite bacterial strains Z2 and Z1 in Example 2: (a) Growth curves of multifunctional composite bacterial strains Z2 and PZ-3, K1, CLSD-1 and WP9; (b) pH change graphs of multifunctional composite bacterial strains Z2 and PZ-3, K1, CLSD-1 and WP9; (c) Growth curves of multifunctional composite bacterial strains Z1 and PZ-3, CLSD-1 and WP9; (d) pH change graphs of multifunctional composite bacterial strains Z1 and PZ-3, CLSD-1 and WP9. Figure 6 This is a graph showing the straw degradation rate determination of the multifunctional composite microbial strain in Example 3; Figure 7 The graph shows the polyglutamic acid production of the multifunctional composite bacterial strain in Example 4. Detailed Implementation

[0024] Those skilled in the art can refer to the content of this document and appropriately improve the process parameters to achieve the desired results. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can obviously make modifications or appropriate alterations and combinations to the methods and applications described herein without departing from the content and scope of this invention to implement and apply the technology of this invention.

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0026] The strains used in the following examples are as follows: Bacillus cereus ( Bacillus cereus K1's accession number is CCTCC NO: M 2026655, and its classification is named as follows: Bacillus cereus It is deposited at the China Center for Type Culture Collection, on April 13, 2026.

[0027] Basophilic Pseudomonas ( Pseudomonas alcaliphila The accession number for WP9 is CCTCC NO: M 2026656, and its classification is named as follows: Pseudomonas alcaliphila It is deposited at the China Center for Type Culture Collection, on April 13, 2026.

[0028] Streptomyces flavus ( Streptomyces microflavus CLSD-1 is disclosed in the patent application number 202311503269.7, and the accession number of Streptomyces flavus CLSD-1 is CCTCC NO: M 2023664.

[0029] Bacillus belysinus ( Bacillus velezensis PZ-3 is disclosed in the patent application number 202311612463.9, and the accession number of Bacillus vesiculosus PZ-3 is CCTCC NO: M 20231826.

[0030] The culture medium used in the following examples has the following composition: Modified potassium feldspar culture medium: 5.0 g / L sucrose, 5.0 mg / L FeCl3, 0.5 g / L MgSO4·7H2O, 2.0 g / L Na2HPO3, 0.1 g / L CaCO3, 1.0 g / L potassium feldspar powder, with 1 mol / L Na2CO3 added to adjust the pH to 9.0. The potassium feldspar is passed through a 300-mesh sieve, soaked in deionized water overnight, then washed thoroughly with deionized water 3-5 times to remove soluble potassium, and air-dried for later use.

[0031] Modified polyglutamic acid separation medium: glucose 20.0 g / L, yeast extract 5.0 g / L, sodium L-glutamate 10.0 g / L, NaCl 5.0 g / L, MgSO4 0.25 g / L, K2HPO4 2.0 g / L, MnSO4·H2O 0.03 g / L, with 1 mol / L Na2CO3 added to adjust the pH to 9.0.

[0032] The improved culture medium consisted of: 10 g / L sucrose, 2.0 g / L Na₂HPO₄, 1.0 g / L CaCO₃, 1.0 g / L (NH₄)₂SO₄, 0.5 g / L yeast extract, 0.5 g / L MgSO₄·7H₂O, 5 g / L straw, 2 g / L Ca₃(PO₄)₂, and 10 g / L potassium feldspar powder. 5% NaCl was added, and the pH was adjusted to 7.5 using 1 mol / L Na₂CO₃ solution. The potassium feldspar was passed through an 180-mesh sieve, soaked in deionized water overnight, and then thoroughly washed 3-5 times with deionized water to remove soluble potassium. It was then air-dried for later use.

[0033] Example 1: Screening of functional strains 1. Screening of polyglutamic acid-producing growth-promoting bacteria: Using Qiqihar Livestock Farm (E124°12) as an example... N47°35 Soil was collected as raw material, and a solution diluted 10% was prepared. -6 10 -7 10 -8 A soil suspension was prepared at multiples of 100 μL, with 100 μL taken from each dilution gradient and spread onto modified polyglutamic acid isolation medium. The culture was incubated at 15°C to observe bacterial growth. Single colonies that grew rapidly, had a smooth, viscous surface, and exhibited stringy texture were selected for further streak plating for purification until single colonies were obtained (single colony morphology as shown in the image). Figure 1 (As shown).

[0034] Genomic DNA was extracted from the functional strains selected above and used as a template for 16S rRNA gene amplification using universal primers 27F (nucleotide sequence shown in SEQ ID NO.1) and 1492R (nucleotide sequence shown in SEQ ID NO.2). The PCR amplification products were sent to Sangon Biotech (Shanghai) Co., Ltd. for sequencing. Homology analysis of the sequencing results was performed using the NCBINucleotide Blast tool, comparing homology with known sequences to determine the taxonomic affiliation of the selected strains. Figure 2 As shown, the strains obtained from the above screening can be identified as *Pseudomonas basophila* (…). Pseudomonas alcaliphila They were named basophilic pseudomonas WP9, and the 16S rRNA of basophilic pseudomonas WP9 is shown in SEQ ID NO.3, with accession number CCTCC NO: M 2026656.

[0035] 2. Screening of potassium-solubilizing bacteria: Using Shuangcheng farmland (E125º41) as an example... N45°08 Soil was collected as raw material, and a solution diluted 10% was prepared. -6 10 -7 10 -8 Soil suspension was diluted 100 μL per dilution, and 100 μL of each dilution was spread onto modified potassium feldspar medium. The strains were incubated at 15°C to observe growth. The shape, color, protrusions, surface condition, and texture of the bacterial communities were observed. Strains with distinct colony morphology were selected for streak plating and purification. The purified strains were then inoculated onto LB slant agar and stored at 4°C (single colony morphology as shown in the image). Figure 3 (As shown).

[0036] Genomic DNA was extracted from the functional strains selected above and used as a template for 16S rRNA gene amplification using universal primers 27F (nucleotide sequence shown in SEQ ID NO.1) and 1492R (nucleotide sequence shown in SEQ ID NO.2). The PCR amplification products were sent to Sangon Biotech (Shanghai) Co., Ltd. for sequencing. Homology analysis of the sequencing results was performed using the NCBINucleotide Blast tool, comparing homology with known sequences to determine the taxonomic affiliation of the selected strains. Figure 4 As shown, the strains obtained from the above screening can be identified as Bacillus cereus (Bacillus cereus). Bacillus cereus They were named Bacillus cereus K1, and the 16S rRNA of Bacillus cereus K1 is shown in SEQ ID NO.4, with accession number CCTCC NO: M 2026655.

[0037] Example 2: Construction of a multifunctional composite microbial system The functional strains (Bacillus cereus K1 and Pseudomonas alkalophilus WP9) obtained in Example 1, along with Bacillus belyssus PZ-3 and Streptomyces flavus CLSD-1, were combined and mixed in a mass ratio of 1:1:1:1 to obtain the multifunctional composite bacterial strain Z2.

[0038] The functional strains (Bacillus belyssus PZ-3 and Pseudomonas alkalophilus WP9) obtained in Example 1 and Streptomyces flavus CLSD-1 were combined and mixed in a mass ratio of 1:1:1 to obtain the multifunctional composite strain Z1.

[0039] The growth curves and pH changes of the culture medium for the obtained multifunctional compound bacterial strains Z1 and Z2, as well as the single bacteria used in each multifunctional compound bacterial strain, were measured. The single bacteria and their corresponding multifunctional compound bacterial strains were inoculated into 300 mL LB liquid medium and cultured with shaking at 15℃ and 180 rpm for 1-2 days until the viable count in the bacterial solution reached 2 × 10⁻⁶. 8 CFU / mL, the bacterial suspensions were inoculated onto the modified bacterial culture medium at an equal volume ratio, and incubated statically at 15℃ for 15 days. The bacterial suspensions were sampled every day, and their absorbance at a wavelength of 600 nm was measured to detect the effect of combined culture on the growth of the bacterial strains.

[0040] like Figure 5 As shown, the multifunctional composite bacterial strain Z2 prepared in this embodiment maintained its activity under low temperature and saline-alkali conditions and reached a plateau on day 8. By comparing the growth status of multifunctional composite bacterial strains Z1 and Z2, it was found that the growth status of the incomplete multifunctional composite bacterial strain Z1 was lower than that of the complete multifunctional composite bacterial strain Z2.

[0041] Example 3: Determination of straw degradation capacity The multifunctional composite bacterial strains Z1 and Z2 obtained in Example 2, Bacillus cereus K1 and Pseudomonas alkalophilus WP9 screened in Example 1, and Bacillus belyssus PZ-3 and Streptomyces flavus CLSD-1 were inoculated into the modified bacterial culture medium at an inoculation rate of 2% and cultured statically at 15°C for 15 days. After drying the straw at 105°C for 8 hours, the above-mentioned bacterial solution was added to determine the straw degradation rate.

[0042] like Figure 6As shown, the straw degradation rate of the multifunctional composite microbial strains was better than that of the single strains. Specifically, the straw degradation capacity of the multifunctional composite microbial strain Z2 was 16.39%, while that of the multifunctional composite microbial strain Z1 was 9.60%. It can be seen that compared with the complete multifunctional composite microbial strain Z2, the straw degradation rate of the incomplete multifunctional composite microbial strain Z1 was reduced by 41.4%.

[0043] Example 4: Determination of polyglutamic acid production capacity The multifunctional composite bacterial strains Z1 and Z2 obtained in Example 2, Bacillus cereus K1 and Pseudomonas alkalophilus WP9 screened in Example 1, and Bacillus belye PZ-3 and Streptomyces flavus CLSD-1 were inoculated into 50 mL of fermentation medium at an inoculation rate of 2%. The cultures were shaken and cultured at 30 °C and 180 rpm for 72 h. The fermentation broth was then centrifuged at 12,000 rpm for 20 min. The supernatant was collected and 4 volumes of pre-cooled anhydrous ethanol were added. The mixture was allowed to precipitate overnight. The precipitate was collected by centrifugation and dissolved in an equal volume of sterile water. The mixture was dialyzed overnight and then mixed with a prepared NaOH solution of hexadecyltrimethylammonium bromide (CTAB) (5% CTAB dissolved in 8% NaOH). The mixture was allowed to stand and the presence of flocculent matter was observed to quickly determine whether polyglutamic acid could be produced. The flocculent precipitate was collected by centrifugation and weighed to determine the polyglutamic acid yield.

[0044] like Figure 7 As shown, the polyglutamic acid synthesis amount of the multifunctional composite bacterial strain Z2 was 1.82 g / L, while that of the multifunctional composite bacterial strain Z1 was 1.07 g / L; moreover, the polyglutamic acid synthesis amount of the multifunctional composite bacterial strain Z2 was better than that of the single strain.

[0045] Therefore, it can be seen that the Bacillus berberis provided by the present invention ( Bacillus velezensis PZ-3, Bacillus cereus ( Bacillus cereus K1, Streptomyces flavus ( Streptomyces microflavus CLSD-1 and basophilic pseudomonas ( Pseudomonas alcaliphila The multifunctional compound bacterial strain Z2, composed of WP9, has a better growth status and can better exert its functions through synergistic effects.

[0046] Example 5: Pot Experiment of Biological Soil Conditioner The potted plant experiment was set up with 3 treatment groups and a control group, as follows: Treatment Group 1 (T1): The carrier matrix additive consists of 1 part chitosan, 2 parts polyacrylamide, and 97 parts biogas residue. Each 1 kg of carrier matrix additive is mixed with 50 g of multifunctional compound bacteria Z1 to prepare a biological saline-alkali soil conditioner. The biological saline-alkali soil conditioner is applied at a rate of 2 L / mu.

[0047] Treatment Group 2 (T2): The carrier matrix excipient consists of 1 part chitosan, 2 parts polyacrylamide, and 97 parts biogas residue. Each 1 kg of carrier matrix excipient is mixed with 50 g of multifunctional compound bacteria Z2 to prepare a biological saline-alkali soil conditioner. The biological saline-alkali soil conditioner is applied at a rate of 2 L / mu.

[0048] Treatment group 3 (T3): Apply multifunctional compound microbial strain Z2 alone at a dosage of 2L / acre.

[0049] Control group (CK): No biological saline-alkali soil conditioner was added, and the other conditions were the same as those of treatment groups 1-3.

[0050] Soybeans were selected as the experimental material. Flowerpots with a diameter of 25 cm and a height of 30 cm were used, each containing 15 kg of soil. Each group had 5 replicates, for a total of 100 pots. Three seeds were sown in each pot at the time of sowing. After the cotyledons unfolded and the true leaves emerged, thinning was carried out, leaving one plant per pot. All potted plants were placed in the smart greenhouse of Northeast Forestry University under natural light, and the soil moisture content was checked regularly to determine whether watering was needed. The plants were sampled and tested during the seedling and flowering stages, and the yield was measured at maturity.

[0051] As shown in Table 1, there were no significant differences in fresh weight, dry weight, plant height, and stem diameter among the treatment groups during the seedling stage, except that the dry weight of T3 (0.37±0.09b) was significantly lower than that of CK (0.52±0.21a). Differences among treatments began to appear at the flowering stage. T2 was significantly higher than CK (37.07±7.51b, 9.83±1.97b, 5.70±0.57b) in fresh weight (58.35±9.56a), dry weight (16.57±1.94a), and stem diameter (9.54±0.83a), and also higher than T1 and T3. There were no significant differences in plant height among the treatments, with T1 showing the highest value (94.51cm), but statistically, it was not significantly different from CK. In summary, T2 showed the most stable growth-promoting effect, especially in increasing biomass and stem diameter during the flowering stage, which was significantly better than other treatments, indicating a synergistic effect between T2 and the carrier combination.

[0052] Table 1 Soybean plant growth indicators

[0053] Note: Different lowercase letters indicate significant differences. P <0.05).

[0054] Yield measurements were performed on potted soybean plants at maturity, and the results are shown in Table 2. There was no significant difference in 100-seed weight among the treatment groups, all ranging from 25.26 to 25.99 g. Regarding the number of pods per plant, T2 (48.53±4.68a) was significantly higher than CK (33.50±5.36b), an increase of 44.9% compared to CK, while T1 and T3 showed no significant difference compared to CK. In terms of yield per mu (a Chinese unit of area, approximately 0.067 hectares), T2 (445.06±42.94a) was significantly higher than CK (313.43±50.13b), an increase of 42.0% compared to CK, while T1 and T3 showed no significant difference compared to CK. Considering all yield indicators, only T2 significantly outperformed CK in both the number of pods per plant and yield per mu, indicating that the conditioner combined with the carrier had the most significant effect on increasing soybean yield.

[0055] Table 2 Results of soybean yield determination at maturity

[0056] Note: Different lowercase letters indicate significant differences. P <0.05).

[0057] Based on data from the seedling stage, flowering stage, and yield measurement, the biological soil conditioner (containing the multifunctional compound microbial system Z2) provided by this invention has a significant effect on promoting soybean plant growth and can significantly increase soybean yield.

[0058] Example 6: Plot trial of biological soil conditioner The experimental plots were set up in the Science and Technology Innovation Park of the Qiqihar Branch of the Heilongjiang Academy of Agricultural Sciences to measure the effects of soil conditioners on maize growth, development, yield, and soil water retention.

[0059] The potted plant experiment was set up with 3 treatment groups and a control group, with 3 replicates in each group. Treatment Group 1 (J1): The carrier matrix excipient consists of 1 part chitosan, 2 parts polyacrylamide, and 97 parts biogas residue. Each 1 kg of carrier matrix excipient is mixed with 50 g of multifunctional compound bacteria Z1 to prepare a biological saline-alkali soil conditioner. The biological saline-alkali soil conditioner is applied at a rate of 2 L / mu.

[0060] Treatment Group 2 (J2): The carrier matrix excipient consists of 1 part chitosan, 2 parts polyacrylamide, and 97 parts biogas residue. Each 1 kg of carrier matrix excipient is mixed with 50 g of multifunctional compound bacteria Z2 to prepare a biological saline-alkali soil conditioner. The biological saline-alkali soil conditioner is applied at a rate of 2 L / mu.

[0061] Treatment group 3 (J3): Apply multifunctional compound microbial strain Z2 alone at a dosage of 2L / mu.

[0062] Control group (CK): No biological saline-alkali soil conditioner was added, and the other conditions were the same as those of treatment groups 1-3.

[0063] 1. During the seedling stage (24 days after sowing) and silking stage of maize, five sampling points were selected in each experimental plot according to the four directions of east, west, south, north and the center. Three representative plants with consistent growth were selected from each point. After sampling, the fresh weight, plant height and stem diameter of the plants were measured immediately. Then the plant samples were placed in an oven at 105℃ for 30 min to kill the green, and then dried at 80℃ to constant weight. After cooling, the dry weight was measured.

[0064] 2. During the corn ripening period, conduct yield measurement work in field plots.

[0065] 3. Soil samples were collected from the Qiqihar Branch of the Heilongjiang Academy of Agricultural Sciences Science and Technology Innovation Park (Base) before spring sowing in April and after harvest in October. The basic physicochemical properties of the soil samples collected before spring sowing were used as the baseline values ​​for the experimental field. The collected soil samples were air-dried, sieved, brought back to the laboratory, sealed and stored, and their basic physicochemical properties were measured. Soil pH was measured using the potentiometry method, soil bulk density was measured using the classical ring cutter method, and soil aggregate structure was measured using the wet sieving method.

[0066] The growth indicators of maize plants are shown in Table 3. During the seedling stage, there were no significant differences in plant height, fresh weight, and dry weight among the treatment groups. Regarding stem diameter: J1 (6.89±0.61b) was significantly lower than CK (7.33±0.91a), J2 (7.22±0.31a), and J3 (7.39±1.09a), while J2 showed no significant difference from CK. During the silking stage, there were no significant differences in plant height, fresh weight, and dry weight among the treatment groups. Regarding stem diameter: J2 (33.50±1.87a) was significantly higher than CK (27.08±2.76b), while J1 (31.15±1.57ab) and J3 (32.50±3.99ab) showed no significant difference from CK.

[0067] Based on data from both the seedling and silking stages, the J2 treatment showed significantly better stem diameter than the CK treatment during the flowering stage, while the J1 treatment showed a lower stem diameter than the CK treatment during the seedling stage. This indicates that the bio-based saline-alkali soil conditioner obtained by combining the multifunctional compound microbial strain Z2 provided by this invention with the carrier matrix additives has a stable promoting effect on corn stalk thickening, and its effect is better than that of J1 and J3.

[0068] Table 3. Growth Indicators of Maize Plants

[0069] Note: Different lowercase letters indicate significant differences. P <0.05) The yield results of maize at maturity are shown in Table 4. Regarding ear diameter: J2 (5.20±0.26a) and J3 (5.33±0.29a) were significantly higher than CK (4.80±0.01b), while J1 (5.12±0.16ab) showed no significant difference from CK. There were no significant differences in ear length, moisture content, or number of plants per mu among the treatments. Regarding 100-kernel weight: J1 (35.14±0.25a) and J2 (32.33±0.01a) were significantly higher than CK (29.81±1.92b), while J3 (35.27±1.01b) showed no significant difference from CK. In terms of seed yield: J1 (81.01±1.29a) and J2 (81.55±1.66a) were significantly higher than CK (77.67±1.93b), while J3 (78.05±1.77b) showed no significant difference from CK. In terms of yield per mu (667 square meters): J2 (853.42±32.06a) was significantly higher than CK (693.85±34.28b), J1 (778.72±30.23b), and J3 (708.78±22.93c), with J2 showing a 23.0% increase over CK.

[0070] Based on comprehensive yield indicators, the J2 treatment showed excellent performance in ear diameter, 100-grain weight, shelling rate, and yield per mu, with the yield per mu being significantly higher than all other treatment groups. This indicates that the bio-type saline-alkali soil conditioner obtained by combining the multifunctional compound microbial system Z2 provided by this invention with the carrier matrix additives has the best effect on improving maize yield.

[0071] Table 4. Maize Yield Measurement Results at Maturity

[0072] Note: Different lowercase letters indicate significant differences. P <0.05).

[0073] The results of soil physicochemical property testing are shown in Table 5. Compared with the baseline values ​​before sowing, the soil pH and bulk density of each treatment group decreased at maturity, while the moisture content increased. Among them, the J2 treatment had the highest moisture content (15.34±1.02a), significantly higher than CK (12.70±2.51b) and J3 (13.21±0.65bc); the soil bulk density (1.19±0.06b) was the lowest among all treatments. Regarding the composition of soil aggregates, the proportion of <0.25 mm microaggregates in the J2 treatment (9.52±2.95b) was significantly lower than the baseline value (20.23±1.39a) and CK (14.83±3.63ab), while the proportions of 0.25-0.5 mm and 0.5-1 mm particle sizes increased. It is evident that the J2 treatment is the most effective in increasing soil moisture content, reducing bulk density, and decreasing the proportion of micro-aggregates; this indicates that the bio-based saline-alkali soil conditioner obtained by combining the multifunctional composite microbial strain Z2 and the carrier matrix excipients provided by this invention can effectively improve soil structure and enhance water retention capacity.

[0074] In summary, the biological saline-alkali soil conditioner obtained by applying the multifunctional compound microbial strain Z2 provided by this invention in combination with carrier matrix excipients can further optimize the physical and chemical properties of the soil, especially in terms of improving soil moisture content and improving aggregate structure, thus providing favorable soil conditions for increased crop yield.

[0075] Table 5. Measurement of soil water retention capacity

[0076] Note: Different lowercase letters indicate significant differences. P <0.05).

[0077] The specific embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific embodiments described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A biological saline-alkali soil conditioner, characterized in that, The biological saline-alkali soil conditioner is obtained by mixing the multifunctional compound microbial system Z2 and the carrier matrix additive in a mass ratio of 1:(20-50).

2. The biological saline-alkali soil conditioner according to claim 1, characterized in that, The multifunctional composite bacterial strain Z2 is composed of Bacillus belysinus (… Bacillus velezensis PZ-3, Bacillus cereus ( Bacillus cereus K1, Streptomyces flavus ( Streptomyces microflavus CLSD-1 and basophilic pseudomonas ( Pseudomonas alcaliphila It consists of WP9.

3. The biological saline-alkali soil conditioner according to claim 2, characterized in that, The mass ratio of Bacillus vesicles PZ-3, Bacillus cereus K1, Streptomyces flavus CLSD-1, and Pseudomonas alkalophilus WP9 in the multifunctional composite bacterial strain Z2 is (0.8-1.2):(0.8-1.2):(0.8-1.2):(0.8-1.2).

4. The biological saline-alkali soil conditioner according to claim 2, characterized in that, The accession number of Bacillus belyssus PZ-3 is CCTCC NO: M 20231826, the accession number of Bacillus cereus K1 is CCTCC NO: M 2026655, the accession number of Streptomyces flavus CLSD-1 is CCTCC NO: M 2023664, and the accession number of Pseudomonas basophila WP9 is CCTCC NO: M 2026656.

5. The biological saline-alkali soil conditioner according to claim 1, characterized in that, The carrier matrix auxiliary material is composed of the following components, by weight: 1-2 parts chitosan, 2-4 parts polyacrylamide, and 94-97 parts biogas residue.

6. A method for preparing the biological saline-alkali soil conditioner according to any one of claims 1 to 5, characterized in that, The preparation method includes the following steps: S1: Composite bacterial culture: Bacillus belye PZ-3, Bacillus cereus K1, Streptomyces flavus CLSD-1 and Pseudomonas alkalophilus WP9 were combined in a certain mass ratio to obtain a multifunctional composite bacterial culture Z2; S2: Carrier matrix excipient premixing: Chitosan, polyacrylamide and biogas residue are premixed to obtain carrier matrix excipients; S3: Conditioner preparation: Mix the multifunctional composite microbial system Z2 obtained in S1 with the carrier matrix excipient obtained in S2 evenly to obtain a biological saline-alkali soil conditioner.

7. The application of the biological saline-alkali soil conditioner according to any one of claims 1 to 5 in improving saline-alkali soil.

8. The application according to claim 7, characterized in that, The biological saline-alkali soil conditioner has at least one of the following functions (1)-(7): (1) It maintains its activity in saline-alkali soil environments with temperatures ranging from 0 to 15℃ and pH values ​​from 7.5 to 9.5; (2) Lower soil pH; (3) Increase soil moisture content; (4) Improve soil physical and chemical properties; (5) Degrading straw; (6) Promotes aggregate formation; (7) Increase crop yield.

9. The application according to claim 7, characterized in that, The application rate of the biological saline-alkali soil conditioner in this application is 50-100 kg per acre.

10. The application according to claim 7, characterized in that, The method of using the biological saline-alkali soil conditioner in this application is as follows: apply the biological saline-alkali soil conditioner to the seeds at the same time as sowing.

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