A method for improving saline-alkali wasteland based on agricultural microorganisms

Abstract

The application discloses a method for improving saline-alkali wasteland based on agricultural microorganisms. The method comprises the following steps: step one, site selection; step two, improving the saline-alkali wasteland by adopting a two-year planting mode, and the specific operation comprises the following steps: S21, applying solid and / or microbial liquid organic fertilizer in the autumn of the first year; S22, leveling the land again before sowing in spring, and breaking large soil into small particles; S23, seed dressing with alkali-resistant powder before sowing; S24, drip irrigation for seedling protection after sowing; S25, base fertilizer, applying compound fertilizer before ploughing; S26, drip irrigation of microbial liquid organic fertilizer for topdressing; S27, foliar fertilizer, spraying foliar fertilizer 1-2 times in the middle and late growth periods of crops; S28, after the crops are harvested, the straw is crushed and returned to the field; and S29, repeating steps S21-S28 when crops are planted in the second year. The method has the advantages that the saline-alkali wasteland can be quickly converted into good farmland in a low-cost and pollution-free manner.

Description

Technical Field

[0001] This invention relates to a method for improving saline-alkali wasteland based on agricultural microorganisms. Background Technology

[0002] One constraint on agriculture is the scarcity of arable land resources. my country has over 500 million mu (approximately 33 million hectares) of saline-alkali land as reserve arable land resources. Therefore, it was decided to concentrate human and material resources to comprehensively develop and utilize saline-alkali land resources, officially making saline-alkali land resource development and utilization a national strategy. Within Ningxia, the Yellow River basin has millions of mu (approximately 66.7 hectares) of saline-alkali land that needs improvement, and a large amount of riverbank saline-alkali wasteland awaits development and utilization.

[0003] Traditional measures for improving saline-alkali land include: (1) lowering the groundwater level through physical (hydraulic) measures (deep ditches / underground pipes) to prevent saline water from remaining in the topsoil, which is a crucial step; (2) in areas where conditions permit, large-scale water leaching can be used to drain salt from deep ditches / underground pipes to reduce the salinity of the topsoil; (3) lowering the soil pH through chemical methods, such as using acidic substances like fly ash, phosphogypsum powder, and furfural residue; and applying organic fertilizers to increase soil organic matter and improve soil structure. These measures allow crops to begin growing on saline-alkali land, and as the planting years increase, the soil condition improves, turning it into fertile land. Over the past half-century, these physical and chemical measures have transformed many saline-alkali wastelands into fertile land, greatly increasing my country's arable land area. Under the new circumstances, the original physical and chemical measures can no longer meet the requirements for improving saline-alkali wasteland. The saline-alkali land resources that can be improved and utilized in my country have been basically transformed. The remaining saline-alkali wasteland is difficult to improve with the original technical means (physical and chemical measures). The main reason is that chemical methods are no longer feasible for improving saline-alkali land, and phosphogypsum powder and fly ash are no longer allowed to be applied to farmland because these raw materials are difficult to avoid causing heavy metal pollution.

[0004] Therefore, it is necessary to develop a green, environmentally friendly, and pollution-free method for improving saline-alkali land in agriculture. Summary of the Invention

[0005] The purpose of this invention is to provide a method for improving saline-alkali wasteland based on agricultural microorganisms. This method is green, environmentally friendly, and pollution-free, and can effectively improve the physical and chemical properties of soil and the soil micro-ecological environment. It can improve saline-alkali land, promote the sustainable development of saline-alkali agricultural ecosystems, and transform saline-alkali wasteland into fertile land. It also solves the problems of heavy metal pollution caused by chemical improvement of saline-alkali wasteland.

[0006] To achieve the above objectives, the technical solution of the present invention is: a method for improving saline-alkali wasteland based on agricultural microorganisms, characterized by comprising the following steps,

[0007] Step 1: Site selection, confirming that the saline-alkali wasteland to be improved meets the improvement requirements;

[0008] The improvement requirements are as follows: the groundwater level should be below 1.5 meters. If the groundwater level is high, water conservancy measures (digging deep ditches or burying underground pipes) should be taken to lower the water level to ensure that the roots of the crops to be planted are not submerged by groundwater; the land within the same plot should be flat and without low-lying areas.

[0009] Step Two: Improve saline-alkali wasteland using a two-year planting model. Specific operations include:

[0010] S21: Apply solid and / or microbial liquid organic fertilizer (containing more than 1 million / gram of salt-alkali resistant microorganisms) in the autumn of the first year at a rate of 5-20 cubic meters (20 tons) per mu. Alternatively, solid organic fertilizer and liquid organic fertilizer can be mixed and applied evenly by spreading or spraying before tilling.

[0011] S22: Level the land again before spring sowing, breaking large clods of soil into small particles;

[0012] S23: Before sowing, treat seeds with alkali-resistant powder at a rate of 3 grams per kilogram of seeds. For seeds that require coating, treat them with alkali-resistant powder after the coating has dried to form a high-concentration salt-alkali resistant microbial community on the seed surface.

[0013] S24: After sowing, drip irrigation is used to promote seedling emergence. 1-2 kg / mu of seedling emergence protection is dripped with water to form a medium concentration of salt-alkali resistant microbial community in the soil around the seeds.

[0014] S25: Apply base fertilizer: Apply 20 kg / mu of compound fertilizer (45% nutrient content) before plowing;

[0015] S26: Apply top dressing:

[0016] After the crops emerge, when the seedlings are about 10 cm tall, apply 10 kg / mu of microbial liquid organic fertilizer (containing 1 million CFU / mL of salt-resistant microorganisms, the same below) by drip irrigation.

[0017] When the seedlings are about 15-20 cm tall, apply 20 kg / mu of microbial liquid organic fertilizer and 7 kg / mu of compound fertilizer in the second drip irrigation.

[0018] When the seedlings are about 30-40 cm tall, apply 30 kg / mu of microbial liquid organic fertilizer and 7 kg / mu of compound fertilizer via drip irrigation for the third time. At this time, chemical fertilizers can be applied, and the amount of chemical fertilizer should be determined according to the corn variety and soil conditions.

[0019] When the seedlings are about 50-70 cm tall, apply the fourth drip irrigation of microbial liquid organic fertilizer at 40 kg / mu and compound fertilizer at 10 kg / mu. At this time, chemical fertilizer can be applied, and the amount of chemical fertilizer should be determined according to the corn variety and soil conditions.

[0020] S27: Apply foliar fertilizer:

[0021] During the middle and late stages of crop growth, spray foliar protectant 1-2 times, 500 ml / mu each time, diluted with 5 kg of water, and spray using a drone;

[0022] Other agricultural operations and cultivation measures (such as intertillage, weeding, growth control, watering, and pest and disease control) can be carried out by following expert advice or by farmers themselves.

[0023] S28: After harvesting crops, crush the straw and return it to the field, spray 1-2 tons / mu of high nitrogen organic liquid fertilizer, and add 5 kg / mu of straw decomposition bacteria agent; then plow it into the soil to promote straw decomposition and rapidly increase soil organic matter.

[0024] S29: Repeat steps S21 to S28 when planting crops in the second year.

[0025] Depending on the actual situation, organic fertilizer may be omitted or applied in small amounts; crops (such as corn) may be planted as described above; after harvesting the crops, the straw may be crushed and returned to the field, and 1-2 tons / acre of high-nitrogen organic liquid fertilizer may be sprayed, along with 5 kg / acre of straw decomposition bacteria agent; then the straw may be plowed into the soil to promote straw decomposition and rapidly increase soil organic matter.

[0026] In the above technical solution, in step S21, the solid microbial organic fertilizer is: livestock and poultry manure is composted at high temperature and then a microbial agent that stimulates plants to resist salt and alkali is added, with a content of 1 million / gram.

[0027] Liquid microbial organic fertilizer is made from harmlessly treated liquids, such as biogas slurry or culture medium produced from monosodium glutamate fermentation, with added microbial agents that stimulate plant tolerance to salt and alkali, at a concentration of 1 million CFU / ml. (CFU stands for Colony Formation Unit, which is the number of viable bacteria).

[0028] In the above technical solution, in step S23, the ratio and preparation method of the alkali-resistant powder are as follows: In step S23, the carrier of the alkali-resistant powder is 300-mesh humic acid powder, which contains 200 million CFU / gram (CFU, Colony Formation Unit, which is the number of viable bacteria) of microorganisms that improve the salt and alkali resistance of plants, and the moisture content of the alkali-resistant powder is 8-10%.

[0029] In the above technical solution, in step S24, the seedling protectant is a liquid formulation, the liquid carrier is water, containing 3%-10% amino acids, 1%-5% potassium humate, pH≤7.0, and containing 1 billion CFU / mL of microorganisms that enhance the plant's salt and alkali resistance.

[0030] In the above technical solution, in step S25, the ratio of 45% nutrients in the compound fertilizer is: N:P2O5:K2O=15:15:15; the 45% nutrients in the compound fertilizer are balanced commercial fertilizers, which are commercial chemical fertilizers with a nitrogen, phosphorus and potassium content of 15%.

[0031] In the above technical solution, in step S25, the method for preparing microbial liquid organic fertilizer is as follows: a liquid that has undergone harmless treatment (such as biogas slurry, waste liquid from monosodium glutamate fermentation, etc.) is mixed with a microbial agent that stimulates plant resistance to salt and alkali, with a content of 1 million CFU / mL and pH ≤ 7.0.

[0032] In the above technical solution, the foliar protectant is a liquid formulation with water as the carrier, containing 1 billion CFU / mL of antagonistic microorganisms that inhibit leaf diseases, 0.5% KH2PO4, 1% urea, and 0.1% agricultural spreading agent.

[0033] In the above technical solution, in step S28, the preparation method of the high-nitrogen organic liquid fertilizer and straw composting agent is as follows: using an amino acid liquid fertilizer containing 5% nitrogen as a carrier, add 1 billion CFU / mL of Bacillus subtilis and 0.1 billion CFU / mL of ammonia bacteria. The high-nitrogen organic liquid fertilizer aims to adjust the C / N ratio of straw, making it easier to compost, while the straw composting agent accelerates the decomposition of straw, quickly turning it into organic matter and improving soil structure.

[0034] The present invention has the following advantages:

[0035] (1) Green, environmentally friendly and pollution-free, it can effectively improve the physical and chemical properties of soil and the soil micro-ecological environment, and can improve saline-alkali land and promote the sustainable development of saline-alkali land agricultural ecosystem; it can solve the problems of heavy metal pollution caused by physical and chemical improvement of saline-alkali wasteland.

[0036] (2) This invention uses agricultural microorganisms as the main technology for improving saline-alkali land, combined with other conventional measures (such as inter-cultivation, weeding, growth control, irrigation, pest and disease control, etc.) to develop and utilize saline-alkali wasteland, plant the most important crops (such as corn), achieve the goal of planting and improving at the same time, transform saline-alkali wasteland into fertile land, and break through the bottleneck of traditional saline-alkali land improvement technology. Attached Figure Description

[0037] Figure 1 This is a graph showing the enzyme activity of saline-alkali land at different stages in Example 1 of the present invention.

[0038] Figure 2 This is a Venn diagram of bacteria and fungi in saline-alkali land at different stages in Example 1 of the present invention.

[0039] Figure 3 This is a diagram showing the relative abundance of bacteria and fungi in saline-alkali land at different periods in Example 1 of the present invention.

[0040] Figure 4 This is a principal component analysis diagram of the bacterial and fungal communities in saline-alkali land in Example 1 of the present invention.

[0041] Figure 5 This is a redundancy analysis diagram of the microbial community structure (OTU level) and physicochemical properties of saline-alkali land in Example 1 of the present invention.

[0042] Figure 6 This is a diagram showing the effect of planting corn in the saline-alkali land experimental site and the control group in Example 1 of the present invention.

[0043] Figure 7 This is a map showing the original topography of the experimental field in Example 2 of the present invention.

[0044] Figure 8 This is a diagram showing the effect of planting corn in the saline-alkali land experimental group and the control group in Example 2 of the present invention.

[0045] Figure 9 This is a process flow diagram of the present invention. Detailed Implementation

[0046] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, these descriptions do not constitute a limitation of the present invention and are merely illustrative. The advantages of the present invention will become clearer and easier to understand through this description.

[0047] Example

[0048] The present invention will now be described in detail using an example of soil improvement in a saline-alkali wasteland. This example will also provide guidance for the application of the present invention to soil improvement in other saline-alkali wastelands.

[0049] Example 1: Demonstration experiment of soil improvement and corn planting on saline-alkali wasteland of a farm using the present invention.

[0050] In this embodiment, a farm (N 38°45′; E 106°11′, altitude 1065m) is located on the eastern foothills of a mountain, in the arid and semi-arid region of Northwest China. The average annual temperature is 9.0℃, the average annual precipitation is 212mm, and the average annual evaporation is around 1500mm, with most rainfall concentrated between June and September. The experimental plot of this farm is approximately 50 mu (about 3.3 hectares). Due to the lack of crop growth, it has been abandoned and is saline-alkali land that has not been tilled for many years. The soil is sandy loam, lacks fertility, and has a compacted texture.

[0051] Saline-alkali wasteland refers to uncultivated saline-alkali land with extremely low soil organic matter, a total soluble salt content of 0.6-1.2%, and a pH of around 8-9. Generally, corn varieties have a salt tolerance of only 0.3-0.4%, making them almost unable to grow on saline-alkali wasteland.

[0052] The specific method for improving saline-alkali wasteland soil using the method of the present invention in this embodiment is as follows:

[0053] From 2022 to 2023, corn was planted on saline-alkali wasteland at a farm. The experiment began in mid-to-late March 2022. After a general survey and assessment of the saline-alkali wasteland, a site was selected (as the experimental site for this invention). Deep plowing was carried out on the wasteland before corn sowing, and 1000 kg / mu of organic liquid fertilizer containing salt-alkali resistant microbial agents was sprayed. Organic nutrients and corn salt-alkali resistant microorganisms were incorporated into the soil, establishing a basic microbial community of salt-alkali resistant microorganisms in the virgin saline-alkali soil. Simultaneously, the applied liquid organic fertilizer supported the survival and reproduction of the microorganisms, forming a dominant microbial community in the soil, allowing the corn (corn variety "Dika 159") to successfully grow in the saline-alkali land. The planting pattern was the same for both years, and the specific operations included:

[0054] (1) Seed dressing with "alkali-resistant" powder before sowing: When sowing in early May, use "alkali-resistant" powder to dress the seeds (3g / kg of seeds) to form a high concentration of salt-resistant microbial community on the seed surface;

[0055] (2) After sowing, drip irrigation with "seedling protectant" at a rate of 1-2 kg / mu to form a medium concentration of salt-alkali resistant microbial community in the soil around the seeds.

[0056] (3) Apply base fertilizer: Apply 45% compound fertilizer at 20 kg / mu before plowing.

[0057] (4) Apply topdressing: In mid-June, drip irrigate 10 kg / mu of "microbial organic liquid fertilizer (containing 1 million CFU / mL of salt-alkali resistant microorganisms, the same below)" and 4 kg / mu of compound fertilizer; in late June, drip irrigate 20 kg / mu of "microbial organic liquid fertilizer" and 7 kg / mu of compound fertilizer; in early July, drip irrigate 30 kg / mu of "microbial organic liquid fertilizer" and 7 kg / mu of compound fertilizer; in mid-July, drip irrigate 40 kg / mu of "microbial organic liquid fertilizer" and 10 kg / mu of compound fertilizer; in late July, drip 12 kg / mu of compound fertilizer.

[0058] (4) Apply foliar fertilizer: In the middle and late stages of growth, spray "Foam Protector" twice, 500 ml / mu each time, diluted with 5 kg of water, and spray with drone.

[0059] The method of this invention for soil improvement in saline-alkali abandoned land is a “3+1” method of applying salt-alkali resistant microbial agents and organic fertilizers, including: seed dressing with “alkali resistant” powder before sowing (1); drip irrigation with “seedling protection” after sowing (2); drip irrigation with “microbial organic liquid fertilizer” during the growth period (3); and spraying “foliar protection” (+1) during the middle and late stages of growth. The “3+1” method of applying salt-alkali resistant microbial agents and organic fertilizers of this invention can effectively ensure the healthy growth of corn in saline-alkali land and provide a “3+1” model for microorganisms to improve plant salt-alkali resistance.

[0060] In this embodiment, the alkali-resistant, seedling-protecting, microbial organic liquid fertilizer, foliar protectant, and microorganisms that stimulate plant salt and alkali resistance (i.e., microorganisms that enhance plant salt and alkali resistance) are all commercially available products.

[0061] The control group did not undergo soil improvement on the saline-alkali wasteland. Instead, corn was planted directly on the saline-alkali wasteland in the same area as the experimental site of this invention. The corn variety was "Dica 159". Compound fertilizer was applied during sowing, base fertilizer, and topdressing.

[0062] The first planting was in 2023, using the method of this invention to grow corn of the variety "Dekalb 159". The experimental site for this invention (e.g., Figure 6 As shown in Figure b. Figure 6 Figure b in the figure shows the effect of planting maize in the saline-alkali land experimental field of Example 1 of the present invention. The emergence rate was 85%, the seedling survival rate at maturity was 79%, and the maize yield was 505 kg / mu; the control group (e.g., Figure 6 As shown in Figure a, Figure 6 Figure a in the diagram shows the effect of planting corn in the control group on saline-alkali land in Example 1 of this invention. The emergence rate was 15%, the seedling survival rate at maturity was 5%, and the corn yield was 5 kg / mu. The corn stalks were crushed and returned to the field upon harvest.

[0063] In 2023, the second planting was carried out using the method of this invention to grow corn. The corn variety was "Dika 159". The seedling emergence rate in the experimental field of this invention was 90%, the seedling survival rate at maturity was 85%, and the corn yield was 658 kg / mu. The seedling emergence rate in the control group was 17%, the seedling survival rate at maturity was 6%, and the corn yield was 8 kg / mu.

[0064] The saline-alkali wasteland soil improved by the method of the present invention in this embodiment was tested, and the method is as follows:

[0065] (1) Sample collection

[0066] Soil samples were collected four times over two years from the planting of maize on saline-alkali wasteland. Soil samples were precisely collected from the surface to a depth of 20 cm, using a five-point sampling method with three replicates per sample area. Four treatments were used: the first soil sample was collected in April 2022 before planting (NS0); the second soil sample was collected in October 2022 after maize harvest (NS1); the third soil sample was collected in April 2023 before planting (NS2); and the fourth soil sample was collected in October 2023 after maize harvest (NS3). All samples were quickly transported to the laboratory and stored at -20°C. After collection, each soil sample was thoroughly mixed and sieved through 0.25 mm, 1 mm, and 2 mm sieves. Each treatment was replicated three times. Fresh and air-dried soil samples were tested as required.

[0067] (2) The test results are as follows:

[0068] 2.1 Effects of microbial inoculants on the physicochemical properties of saline-alkali soil

[0069] The physicochemical properties of saline-alkali soils showed certain differences at different stages after the application of microbial fertilizer (as shown in Table 1). Within two years, the soil pH and EC (electrical conductivity, the higher the electrical conductivity, the higher the salinity) at harvest (NS1 and NS3) showed a significant decreasing trend compared to the sowing time (NS0 and NS2); OM (organic matter), DOC (dissolved carbon), AN (available nitrogen), AP (available phosphorus), and AK (available potassium) all increased significantly compared to before sowing, but DOC and AK decreased at the second year's harvest; among the eight major soil ions, Mg... 2+ SO4 2- and HCO3 - Both are showing a downward trend, K + Na + With Cl - It increased after the first year's harvest, then decreased significantly in the second year, Ca 2+ Significant increases were observed in NS1 and NS3, notably, CO3 was not detected in any of the four soil sample analyses. 2- The presence of this indicates that the microbial fertilizer in this invention can reduce soil pH, EC, and the content of some ions harmful to crop growth, while increasing the content of substances beneficial to crop growth such as OM, AN, and AP, showing a positive trend in the improvement of saline-alkali land.

[0070] Table 1. Physicochemical properties of saline-alkali soil at different time points after application of salt-alkali resistant microbial fertilizer.

[0071]

[0072]

[0073] 2.2 Effects of microbial inoculants on enzyme activity in saline-alkali soil

[0074] like Figure 1As shown, compared with the original soil before the first year of sowing, the application of the microbial fertilizer of this invention significantly increased the activities of urease, alkaline phosphatase, and sucrase in saline-alkali soil two years later. Their activities were ranked as follows: NS3 > NS2 > NS1 > NS0, NS3 > NS2 > NS1 > NS0, and NS3 > NS1 > NS2 > NS0, respectively. Soil samples collected at harvest two years later showed the highest activities of all three enzymes compared to other periods. Specifically, soil urease activity NS3 increased by 90.18% compared to NS0, soil alkaline phosphatase activity NS3 increased by 45.67% compared to NS0, and sucrase activity NS3 increased by 82.31% compared to NS0. Soil catalase activity showed the opposite trend to the other three enzymes, with its activities ranked as NS2 > NS0 > NS3 > NS1. Soil catalase activity at each harvest was lower than before sowing. These results indicate that the microbial fertilizer of this invention can increase the beneficial soil enzyme activities and decrease the detrimental soil enzyme activities, showing a positive correlation.

[0075] exist Figure 1 In this context, Urease represents urease in saline-alkali soil; Alkaline phosphatase represents alkaline phosphatase; Sucrose represents sucrase; and Catalase represents catalase. Figure 1 In the diagram, 'a' represents urase activity, 'b' represents alkaline phosphatase activity, 'c' represents sucrase activity, and 'd' represents catalase activity.

[0076] 2.3 Alpha diversity analysis of saline-alkali soil microbial communities by saline-alkali resistant microbial fertilizer

[0077] Soil DNA was sequenced at different time points using the Illumina Miseq PE300 platform. The library coverage of all samples was above 98%, indicating that the sequencing depth could cover most microorganisms in the soil and accurately reflect the microbial community information in each sample. Table 2 shows the Alpha diversity index results of the sequenced soil samples. Ace, Chao, and Sobs indices represent species richness; higher values ​​indicate higher species richness. Shannon and Simpson indices reflect species diversity; a higher Shannon index and a lower Simpson index indicate higher species diversity. In this embodiment, the method of this invention was used to improve the soil. Within two years, the Ace, Chao, and Sobs indices of soil bacteria at harvest time were significantly higher than before sowing. NS3 had the highest species richness, and NS0 had the lowest. The Shannon and Simpson indices of the soil also showed significant differences at different time points, with the Shannon index showing an upward trend and the Simpson index showing the opposite trend. Compared with the richness and diversity of soil bacterial communities at different stages, the Simpson index of fungi did not differ significantly. However, the Shannon, Ace, Chao, and Sobs indices of soil fungi at harvest time were significantly higher than before sowing within two years, with NS3 being the highest and NS0 the lowest. This indicates that applying the microbial fertilizer of this invention can improve the richness and diversity of bacteria and fungi in saline-alkali soils.

[0078] Table 2 Results of Microbial Diversity Index of Saline-Alkali Land

[0079]

[0080] 2.4 Analysis of the Community Structure and Composition of Microbial Fertilizers on Soil Microorganisms in Saline-Alkali Land

[0081] 2.4.1 Number of soil bacteria and fungi at different times

[0082] The number of soil bacteria and fungi OUT (operational taxonomic units) in four periods within two years after the application of salt-alkali resistant microbial fertilizer is as follows: Figure 2 As shown in the Venn diagram of bacteria, a total of 8834 bacterial OTUs were obtained from soil samples collected at four different time periods. NS3 had the most OTUs (5414), while NS0 had the fewest (2643). Analysis of the Venn diagram revealed that 1743 OTUs were common across the four sample groups, accounting for 19.73%. NS0, NS1, NS2, and NS3 had 638, 737, 783, and 1293 OTUs specific to NS0, NS1, NS2, and NS3, respectively, accounting for 7.22%, 8.34%, 8.86%, and 14.64%. NS3 had the highest proportion, and NS0 had the lowest. Figure 2As shown in Figure a. In the Venn diagram of fungi, a total of 896 fungal OTUs were obtained from soil samples collected at four different times. NS3 had the most OTUs (492), while NS0 had the fewest (266). Analysis of the Venn diagram revealed that 68 OTUs were common to all four groups of samples, accounting for 7.59%. NS0, NS1, NS2, and NS3 had 102, 106, 127, and 231 OTUs specific to them, respectively, accounting for 11.38%, 11.83%, 14.17%, and 25.78%. NS3 had the highest percentage, and NS0 had the lowest. Figure 2 As shown in Figure b, the results indicate that the number of soil bacteria and fungi OTUs increased significantly within two years of applying microbial fertilizer, enhancing the number, richness, and diversity of microbial species during the improvement of saline-alkali land.

[0083] 2.4.2 Influence of soil bacterial and fungal horizontal community composition at different stages

[0084] The composition of soil bacteria at the phylum level varied significantly across different time periods. The 10 most abundant bacterial phyla were Proteobacteria, Actinobacteriota, Chloroflexi, Bacteroidota, Firmicutes, Acidobacteriota, Gemmatimonadota, Myxococcota, Patescibacteria, and Cyanobacteria. The dominant bacterial phyla were Proteobacteria, Actinobacteria, and Chloroflexi, accounting for over 70% of the total bacterial community relative abundance. The relative abundance of Proteobacteria increased significantly in both harvest periods (NS1 and NS3). The relative abundance of Actinobacteria decreased progressively across the four periods. The proportion of Chloroflexi remained relatively stable across all periods. Notably, the relative abundance of Acidobacteriota increased continuously across the four periods (e.g., ...). Figure 3 (as shown in Figure a).

[0085] At the fungal level, the dominant community was Ascomycota, with the highest relative abundance, accounting for 80%-95% of the total community. Its proportion remained high at all stages, only decreasing in NS3. Basidiomycota saw an increase in relative abundance in NS3, but Chytridiomycota appeared in the two harvest stages NS1 and NS3. This phylum was not found in the two sowing stages NS0 and NS2 (e.g., ...). Figure 3 (as shown in Figure b).

[0086] The results showed that the application of microbial fertilizer had a significant impact on the Proteobacteria and Acidobacteria phyla of the bacterial community within two years, and had a good effect on improving saline-alkali land. The appearance of the Chytridida phylum of the fungal community due to the application of microbial fertilizer may also play a role in improving saline-alkali land.

[0087] exist Figure 3 In Figures a and b, the vertical axis represents the percentage of community abundance at the Phylum level.

[0088] 2.4.3 Relationship between soil samples and species at different times

[0089] In the phylum-level bacterial Circos, the dominant species in samples from all four time periods were Actinobacteria, Proteobacteria, and Chlorconoidobacteria. In the first year, during the sowing period (NS0), Actinobacteria had the largest proportion (38%–41%), followed by Proteobacteria (25%) and Chlorconoidobacteria (9%). At harvest (NS1), Proteobacteria and Actinobacteria each accounted for approximately 30%, while Chlorconoidobacteria accounted for 11%. Compared to NS0, the proportions of Proteobacteria and Chlorconoidobacteria increased in NS1. In the second year, during the sowing period (NS2), Proteobacteria accounted for 30%, Actinobacteria for 27%, and Chlorconoidobacteria for 10%, with the proportions of Actinobacteria and Chlorconoidobacteria decreasing. At harvest (NS3), Proteobacteria accounted for the largest proportion (35%–38%), followed by Actinobacteria for 19%, and Chlorconoidobacteria for 10%–13%. Compared to before sowing, the proportions of Proteobacteria and Chlorconoidobacteria increased, while the proportion of Actinobacteria decreased. Overall, the results of applying microbial fertilizers to improve saline-alkali land over two years showed an increase in the proportion of Proteobacteria, a decrease in Actinobacteria, and little change in the proportion of Chlorocybenomycota, which were not key factors affecting species.

[0090] In the circos of fungi at the phylum level, Ascomycota were the dominant species in samples from all four time periods, accounting for the largest proportion, followed by Basidiomycota. Ascomycota had the highest proportion at 97% in NS0, decreasing sequentially in NS1, NS2, and NS3, reaching 87% in NS3. Basidiomycota showed a slight increase, from 2% in NS0 to over 6% in NS3. Overall, the application of microbial fertilizers reduced Ascomycota and increased Basidiomycota in saline-alkali soils, altering the species composition of the fungal community. Ascomycota contains many plant pathogens, while Basidiomycota consists primarily of non-pathogenic fungi.

[0091] 2.5 Analysis of the Differences in the Community Structure of Microbial Fertilizers on Soil Microorganisms in Saline-Alkali Land

[0092] PCA (principal component analysis) was performed on the OTU data of bacteria and fungi, and the results are as follows: Figure 4As shown, in the principal component analysis of bacteria and fungi, the three samples from the same treatment were close together, indicating good repeatability. However, the treatments at the four time points showed some distance, indicating certain differences between samples. In the bacterial principal component analysis, the contribution rates of PC1 and PC2 were 21.72% and 15.61%, respectively. The NS2 and NS3 groups were clearly distinguishable from the NS0 and NS1 groups along PC1. In the PC2 analysis, the NS0, NS1, NS2, and NS3 groups were all clearly distinguishable, indicating significant differences in microorganisms among the groups. The NS0 and NS1 groups showed little difference along PC1, with no significant distance between them. Figure 4 As shown in Figure a ( Figure 4 In the graph, the horizontal axis represents principal component 1 with high variance, and the vertical axis represents principal component 2 with low variance (closer distances indicate more similar microbial composition). In the fungal principal component analysis, PC1 and PC2 contributed 17.58% and 12.51%, respectively. In the PC1 analysis, the NS3 group showed significant differences from the NS0, NS1, and NS2 groups, indicating substantial inter-group microbial differences. Conversely, the NS0, NS1, and NS2 groups showed less significant differences. In the PC1 analysis, the NS0, NS1, NS2, and NS3 groups all exhibited some distance, suggesting certain inter-group differences. Figure 4 As shown in Figure b.

[0093] Therefore, in both bacterial and fungal principal component analysis, there was a certain distance between treatments in PC1 and PC2 analyses. This distance indicates that there are significant differences in microorganisms between groups, suggesting that the application of microbial fertilizers in the improvement of saline-alkali soil has a significant impact on soil microbial diversity.

[0094] 2.6 Correlation Analysis of Microbial Fertilizer Effects on Soil Physicochemical Properties and Microbial Community in Saline-Alkali Land

[0095] This study investigated the impact of RDA analysis on the soil physicochemical properties of saline-alkali soils on bacterial community structure at different stages after the application of microbial fertilizers. In the RDA biological community analysis, the combination of RDA1 and RDA2 variables explained 91.27% of the bacterial community variation and 69.82% of the fungal community variation (e.g., ...). Figure 5 As shown, Figure 5 The RDA (Redundancy Analysis) in the text is used to determine the correlation between microbial community structure characteristics and environmental physicochemical factors. The percentages in parentheses on the coordinate axes represent the proportion of differences in the original database that the corresponding coordinate axis can explain. Figure 5 Each point in the diagram represents a sample; the closer two points are, the higher the similarity of the microbiome between the two samples. Figure 5The middle arrows represent environmental physicochemical factors. The smaller the angle between the arrows, the greater the correlation between them (right angles indicate no correlation, and obtuse angles indicate a negative correlation). It can be seen that soil AP, EC, and pH are the main factors affecting bacterial communities. The degree of influence of each physicochemical factor on bacterial communities is AP>EC>pH>OM>AN>DOC>AK. Before the application of microbial fertilizer (NS0), there was a significant positive correlation between NS0 and soil EC and pH, and a significant negative correlation with AP. After the application of microbial fertilizer (NS0), the results were reversed. Figure 5 As shown in Figure a, soil AP, AK, and DOC are the main factors influencing fungal communities. The degree of influence of each physicochemical factor on bacterial communities is AP>AK>DOC>pH>EC>AN>OM. Before the application of microbial fertilizer (NS0), soil EC showed a significant positive correlation with soil EC and a significant negative correlation with AP. After the application of microbial fertilizer (NS0), the results were reversed. Figure 5 As shown in Figure b, the application of microbial fertilizer (AP) has a significant impact on the soil microbial community, playing a crucial role in the improvement of saline-alkali land.

[0096] Conclusion: The above tests revealed the following:

[0097] (1) The microbial fertilizer of the present invention can increase the nutrient content of saline-alkali soil, increase the enzyme activity of saline-alkali soil, reduce the content of harmful physicochemical factors and ions, and improve the improvement effect on saline-alkali soil.

[0098] With the application of microbial fertilizers to improve saline-alkali wasteland, the internal soil environment changes, which in turn affects the physicochemical properties of the saline-alkali soil. Analysis by this invention revealed significant differences in the physicochemical properties of the improved saline-alkali wasteland in a certain farm (as shown in Table 1). Soil pH and EC showed a decreasing trend with the improvement time. The decrease in soil pH and EC led to an increase in OM, AN, and AP in the soil, indicating that high pH and EC affect the utilization rate of OM, AN, and AP by plants. Studies have shown that the application of microbial agents can improve soil desalination rates because some beneficial microorganisms in saline-alkali land can produce polysaccharides and mucilage during their activity, forming soil binders, affecting aggregate structure, reducing bulk density and non-capillary porosity, thereby accelerating soil salt leaching and reducing soil salinity. This is consistent with the finding that Mg in the soil of the experimental site of this invention... 2+ SO4 2- and HCO3 - Both are showing a downward trend, Ca 2+ K increases significantly at harvest. + Na + With Cl -The results showed an increase after the first harvest, followed by a significant decrease in the second year, consistent with previous observations. Microbial fertilizers activate native soil microorganisms, utilizing the rich organic matter in the fertilizer to provide more nutrients for these microorganisms, thereby increasing their numbers. Soil enzymes, acting as a link between plants and nutrients, objectively reflect soil fertility and indirectly influence the cycling of nutrients in the soil. The activities of alkaline phosphatase, sucrase, urease, and catalase in different soil samples are closely related to microbial respiration and biomass, indicating that these soil enzyme activities are the best predictors of microbial population activity and quality. In the experimental field of this invention, the activities of urease, alkaline phosphatase, and sucrase in the soil at harvest time after the application of microbial fertilizer were higher than those in the soil before sowing. This is because the application of biological agents can accelerate the decomposition of organic matter in the soil, providing substrates for enzymatic reactions. Catalase can decompose hydrogen peroxide, which is toxic to plants, and is widely distributed in soil and organisms. The activity of soil catalase at harvest time in the experimental sites of this invention showed a decreasing trend. This was mainly due to the changes in the soil microecological environment after the application of microbial fertilizer, which alleviated salt-alkali stress and reduced the content of hydrogen peroxide, which is harmful to plants. Overall, the application of microbial fertilizer increased the soil nutrient content and enzyme activity in saline-alkali wasteland, and reduced the content of some harmful physicochemical factors and ions, thus having a certain effect on improving saline-alkali soil.

[0099] (2) The microbial fertilizer of the present invention can improve the microbial diversity of saline-alkali soil and enrich the structure and composition of saline-alkali soil microbial community;

[0100] Soil microbial diversity and relative abundance are important indicators of soil fertility. Increasing the number of beneficial microorganisms in the soil can effectively promote plant growth and development. The application of microbial fertilizers not only promotes the formation of new microbial communities around plant roots but also improves the soil's ecological environment. The experimental results of this invention show that, with the application of microbial fertilizers to improve saline-alkali wasteland, the Ace, Chao, and Sobs indices of soil bacteria and fungi at harvest time were significantly higher than before sowing within two years. NS3 had the highest species richness, while NS0 had the lowest. Soil Shannon and Simpson indices also showed significant differences at different times, with the Shannon index increasing and the Simpson index of bacteria decreasing, indicating that the application of microbial fertilizers can improve the diversity and relative abundance of soil microorganisms in saline-alkali wasteland. Studies have shown that the application of microbial fertilizers significantly increases the diversity of soil microbial communities, promotes the proliferation of beneficial bacteria, and thus improves microbial activity. Members of Ascomycota and Basidiomycota are dominant in all soils. Proteobacteria, Acidobacteriota, Bacteroidota, and Actinobacteriota are the dominant bacterial groups in farmland soil. Microbial inoculants can alter the relative abundance of some of these groups to some extent. In the experimental site of this invention, the proportion of bacterial and fungal OTUs in soil samples was highest at the second year of harvest after improvement. The proportions of community composition at the phylum level varied dynamically across different periods. The dominant bacterial phyla were Proteobacteria, Actinobacteria, and Chlorconoidobacteria, accounting for over 70% of the total bacterial community relative abundance. The relative abundance of Proteobacteria increased significantly in both harvest periods, while the relative abundance of Actinobacteria decreased progressively in each period. Chlorconoidobacteria had little impact. Notably, the relative abundance of Acidobacteria increased continuously across all four periods, suggesting it may be a significant factor in the decrease in soil pH. The dominant fungal community was Ascomycota, with the highest relative abundance at all periods. The relative abundance of Basidiomycota increased in the second year of harvest, while Chytridactyta appeared in both harvest periods. At the phylum level, fungal species diversity and richness were lower than bacterial species. The experimental site results of this invention indicate that the application of microbial fertilizers in saline-alkali soil improvement has a certain impact on the Acidobacteria phylum and the Chytridactyta phylum among fungi, and may play a key role in saline-alkali soil improvement.

[0101] (3) The microbial fertilizer of the present invention can change the physical and chemical properties of soil and increase the differences in soil microbial community structure;

[0102] Soil microbial community structure is closely related to the soil environment. Improvement methods can alter soil physicochemical properties, thereby changing the structure of the soil microbial community. Soil type primarily depends on the composition of the microbial community or is influenced by complex interactions between soil and plants. Microbial fertilizers can improve soil fertility by changing the microbial community structure of the rhizosphere soil. In the experimental field of this invention, PCA analysis of OTU data for bacteria and fungi revealed that the contribution rates of bacteria PC1 and PC2 were 21.72% and 15.61%, respectively, while those of fungi PC1 and PC2 were 17.58% and 12.51%, respectively. A certain distance was observed between treatments in the PC1 and PC2 analyses, indicating significant differences in microorganisms between groups. This suggests that the application of microbial fertilizers in saline-alkali soil improvement has a significant impact on soil microbial diversity. Redundancy analysis (RDA) can be used to describe the relationship between soil physicochemical parameters and microbial community distribution. Previous studies have shown that environmental factors such as pH, SOC, AP, and enzyme activity determine the soil microbial community in different ecosystems. The RDA obtained from the experimental site of this invention shows that AP, EC and pH are the main factors determining the bacterial community structure after saline-alkali land improvement, while AP, AK and DOC are the main factors affecting the fungal community structure. This indicates that these physicochemical factors play an important role in the changes of soil microbial community after the application of the microbial fertilizer of this invention, and have great potential in the process of saline-alkali land improvement.

[0103] The experimental site of this invention, after two years of improvement of saline-alkali wasteland, significantly reduced soil pH and EC, and increased the content of physicochemical properties such as OM, DOC, AN, AP, and AK, as well as Ca. 2+ The content increases significantly at harvest, K + Na + Mg 2+ SO4 2- HCO3 - and Cl -The contents of all three showed a decreasing trend. The harvest period significantly increased the activities of soil urease, alkaline phosphatase, and sucrase, while catalase activity decreased. Furthermore, two years of improvement significantly altered the diversity of the microbial community, also significantly affecting the quantity and composition of bacteria and fungi in saline-alkali soil. The three dominant bacterial phyla—Proteobacteria, Actinobacteria, and Chlorconiobacteria—experienced an increase in the proportion of Proteobacteria and Chlorconiobacteria after improvement, while the proportion of Actinobacteria decreased. The dominant fungal phylum, Ascomycota, decreased during the improvement process, and Chytridida appeared in both harvest periods. PCA analysis of bacteria and fungi revealed significant differences in the microbial community during the improvement process. RDA analysis identified AP, EC, and pH as important physicochemical factors affecting soil bacterial community structure, while AP, AK, and DOC were important for fungal community structure, indicating that these factors all contributed to changes in the soil microbial community. This invention provides a scientific basis and data for the improvement of saline-alkali land. In agricultural production, the application of the microbial fertilizer of this invention can regulate the stability of the soil-crop ecosystem to mitigate the degree of saline-alkali stress.

[0104] Example 2: Demonstration experiment of soil improvement and corn planting on saline-alkali abandoned land in a certain county using the present invention.

[0105] Basic information about the experimental field: The experimental plot is located in Dishiyao Village, Wushijia Town, a certain county, in an alluvial fan plain. The soil is highly clayey with low permeability. The topsoil is severely compacted, and the surface is whitish (as shown in the image). Figure 7 (As shown).

[0106] Saline-alkali wasteland refers to uncultivated saline-alkali land with extremely low soil organic matter, a total soluble salt content of 0.6-1.2%, and a pH of around 8-9. Generally, corn varieties have a salt tolerance of only 0.3-0.4%, making them almost unable to grow on saline-alkali wasteland.

[0107] (1) Test location: Dishiyao Village, Wushijia Town, a certain county (longitude 111.6960840, latitude 40.7941610)

[0108] (2) Test soil: Saline-alkali land abandoned for many years; salt content 11.5‰, pH value 9.01;

[0109] (3) Groundwater: 2.5-3.0 meters, pale yellow in color;

[0110] (4) Natural vegetation: perennial salt-tolerant plants such as bitter bean, reed, and sheep grass, with significant bald patches.

[0111] (5) Experimental group: Soil improvement of saline-alkali abandoned land was carried out using the method of the present invention (i.e., using “3+1” series of saline-alkali resistant microbial agents and organic fertilizers);

[0112] The control group was cultivated in natural soil.

[0113] Trials will begin in 2024, with the experimental group (e.g.) Figure 8 The seedling emergence rate in the plot shown on the right (as indicated in the figure on the right) reached 80%, with no stunted seedlings occurring, and the corn seedling performance was close to that of normal farmland soil. The control group plot (as shown in the figure on the right) Figure 8 The germination rate (as shown in the left figure) was 6%, and there were many cases of stunted seedlings.

[0114] The currently accepted criteria for classifying saline-alkali land are: soil with a salt content of 1-3‰ is slightly saline-alkali land; soil with a salt content of 3-6‰ is moderately saline-alkali land; and soil with a salt content of 6-9‰ is severely saline-alkali land. Soil with a salt content exceeding 9‰ is difficult to develop and utilize. Current experimental results show that the novel saline-alkali land improvement method based on microorganisms, as described in this invention, can be used for the development and utilization of saline-alkali wasteland with a salt content of 11.5‰, and is also applicable to the improvement of moderate and severely saline-alkali land. This invention can effectively improve the physical and chemical properties of soil and the soil micro-ecological environment, playing an important role in the development and utilization of saline-alkali wasteland in my country, the improvement of existing saline-alkali land, and the promotion of the sustainable development of saline-alkali land agricultural ecosystems.

[0115] All other unspecified parts belong to the prior art.

Claims

1. A method for improving saline-alkali wasteland based on agricultural microorganisms, characterized in that: It is suitable for the improvement or utilization of saline-alkali wasteland with a salt content of 11.5‰. It provides a 3+1 model for microorganisms to enhance plant salt and alkali resistance, including: pre-sowing alkali-resistant powder seed dressing; post-sowing drip irrigation for seedling protection; drip irrigation with microbial organic liquid fertilizer during the growing season; and foliar spraying for protection during the middle and late stages of growth. The specific method includes the following steps: Step 1: Site selection, confirming that the saline-alkali wasteland to be improved meets the improvement requirements; Step Two: Improve saline-alkali wasteland using a two-year planting model. Specific operations include: S21: Apply solid and / or microbial liquid organic fertilizer in the autumn of the first year, spreading or spraying 5-20 tons / mu evenly before tilling. S22: Level the land again before spring sowing, breaking large clods of soil into small particles; S23: Treat seeds with alkali-resistant powder before sowing; In step S23, the carrier of the alkali-resistant powder is 300-mesh humic acid powder, which contains 200 million CFU / g of microorganisms that enhance the salt and alkali resistance of plants, and the moisture content of the alkali-resistant powder is 8-10%. S24: After sowing, drip irrigation should be used to ensure seedling emergence, with 1-2 kg / mu of seedling emergence protectant applied with drip irrigation water; S25: Apply base fertilizer: Apply 20 kg / mu of compound fertilizer (45% nutrient content) before plowing; S26: Apply top dressing: After the crops emerge, when the seedlings are about 7-12 cm tall, apply 10 kg / mu of microbial liquid organic fertilizer by drip irrigation for the first time. When the seedlings are 15-20 cm tall, apply a second drip irrigation of 20 kg / mu of microbial liquid organic fertilizer and 7 kg / mu of compound fertilizer. When the seedlings are 30-40 cm tall, apply the third drip irrigation with 30 kg / mu of microbial liquid organic fertilizer and 7 kg / mu of compound fertilizer. When the seedlings are 50-70 cm tall, apply the fourth drip irrigation with 40 kg / mu of microbial liquid organic fertilizer and 10 kg / mu of compound fertilizer. S27: Apply foliar fertilizer: In the middle and late stages of crop growth, spray foliar fertilizer 1-2 times, 500 ml / mu each time, diluted with 5 kg of water; S28: After harvesting crops, crush the straw and return it to the field, spray 1-2 tons / mu of high-nitrogen organic liquid fertilizer, and add 5 kg / mu of straw decomposition bacteria agent; then plow it into the soil. S29: Repeat steps S21 to S28 when planting crops in the second year.

2. The method for improving saline-alkali wasteland based on agricultural microorganisms according to claim 1, characterized in that: In step one, the improvement requirements are: the groundwater level is below 1.5 meters to ensure that the roots of the crops to be planted are above the groundwater level; and the land within the same plot is level.

3. The method for improving saline-alkali wasteland based on agricultural microorganisms according to claim 1 or 2, characterized in that: The method for treating seeds with alkali-resistant powder is: 3 grams per kilogram of seeds.

4. The method for improving saline-alkali wasteland based on agricultural microorganisms according to claim 3, characterized in that: In step S25, the ratio of 45% nutrients in the compound fertilizer is: N:P2O5:K2O = 15:15:

15.

5. The method for improving saline-alkali wasteland based on agricultural microorganisms according to claim 4, characterized in that: In step S28, the preparation method of high nitrogen organic liquid fertilizer and straw composting bacteria agent is as follows: using amino acid liquid fertilizer containing 5% nitrogen as a carrier, add 1 billion CFU / mL Bacillus subtilis and 0.1 billion CFU / mL ammonia bacteria.

Images