Method for improving saline-alkali wasteland based on agricultural microorganisms

Abstract

The invention discloses a saline-alkali wasteland improvement method based on agricultural microorganisms. The method comprises the following steps: step 1, site selection; 2, the saline-alkali wasteland is improved in a two-year planting mode, and the specific operation includes the steps that S21, solid and / or microbial liquid organic fertilizer is applied in autumn of the first year; s22, the land is leveled again before sowing in spring, and large soil blocks are crushed into fine particles; s23, mixing the seeds with alkali resistance powder before sowing; s24, drip irrigation of seedling emergence protection after sowing; s25, base fertilizer applying, wherein compound fertilizer is applied before ploughing; s26, drip irrigation of microbial liquid organic fertilizer for topdressing; s27, foliage fertilizer: in the middle and later periods of crop growth, spraying foliage fertilizer for 1-2 times; s28, after the crops are harvested, straw is smashed and returned to the field; and S29, repeating the steps S21 to S28 when crops are planted in the second year. The method has the advantage that the saline-alkali wasteland can be quickly converted into fertile farmland in a low-cost and pollution-free manner.

Description

Technical Field

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

[0002] One of the constraints of agriculture is the lack of arable land resources; my country has more than 500 million mu of saline-alkali land as reserve arable land resources, so it is decided to concentrate manpower and material resources to comprehensively develop and utilize saline-alkali land resources. The development and utilization of saline-alkali land resources has officially become a national strategy. In the Yellow River Basin in Ningxia, there are millions of mu of saline-alkali land that need to be improved, and a large amount of river beach saline-alkali wasteland to be developed and utilized.

[0003] Traditional measures to improve saline-alkali land include: (1) lowering the groundwater level through physical (hydraulic) measures (deep ditches / covered pipes) to prevent saline-alkali water from remaining in the arable layer, which is a key step; (2) where conditions permit, large amounts of water can be used to wash the salt and discharge it from deep ditches / covered pipes to reduce the salinity of the arable layer; (3) using chemical methods, such as fly ash, phosphogypsum powder, furfural slag and other acidic substances to lower the soil pH; applying organic fertilizers to increase soil organic matter and improve soil structure. The above measures allow crops to begin to grow on saline-alkali land. As the number of years of planting increases, the soil condition becomes better and better, and it becomes fertile land. The above physical and chemical measures have transformed many saline-alkali wastelands into fertile land over the past half century, greatly increasing the area of ​​arable land in my country. 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 basically been transformed, and the remaining saline-alkali wasteland is difficult to improve with the original technical means (physical and chemical measures). The main reasons are: 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 inevitably bring heavy metal pollution.

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

[0005] The purpose of the present invention is to provide a method for improving saline-alkali wasteland based on agricultural microorganisms, which is green, environmentally friendly, pollution-free, can effectively improve the physical and chemical properties of soil and the soil microecological environment, improve saline-alkali land, promote the sustainable development of saline-alkali agricultural ecosystem, and transform saline-alkali wasteland into fertile farmland; solve the problems such as heavy metal pollution caused by chemical improvement of saline-alkali wasteland.

[0006] In order to achieve the above object, the technical solution of the present invention is: a method for improving saline-alkali wasteland based on agricultural microorganisms, characterized in that it comprises 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: the groundwater level is below 1.5 meters. If the groundwater level is high, water conservancy measures (digging deep trenches or burying underground pipes) are required to lower the water level to ensure that the roots of crops to be planted are not submerged by groundwater; the land within the same plot is flat and there are no low-lying areas;

[0009] Step 2: Use a two-year planting model to improve saline-alkali wasteland. Specific operations include:

[0010] S21: In the autumn of the first year, apply solid and / or microbial liquid organic fertilizer (containing more than 1 million salt-alkali resistant microorganisms / g), 5-20 cubic meters (20 tons) / mu. You can also mix solid organic fertilizer with liquid organic fertilizer and apply it evenly, then plough after spreading or spraying.

[0011] S22: Level the land again before sowing in spring to break up large clumps of soil into fine particles;

[0012] S23: Mix the seeds with alkali resistance powder before sowing, 3 g / kg seeds. For seeds that need to be coated, mix the seeds with alkali resistance after the coating is dried, so as to form a high concentration of salt-alkali resistant microbial community on the surface of the seeds;

[0013] S24: After sowing, drip irrigation is used to protect seedlings. 1-2 kg / mu of water is used to protect seedlings. A medium concentration of salt-alkali resistant microbial flora is formed in the soil around the seeds.

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

[0015] S26: Applying topdressing:

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

[0017] When the seedlings are about 15 to 20 cm tall, the second drip tank is used to apply 20 kg / mu of microbial liquid organic fertilizer and 7 kg / mu of compound fertilizer;

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

[0019] When the seedling height is about 50-70 cm, the fourth drip tank of microbial liquid organic fertilizer is 40 kg / mu and compound fertilizer is 10 kg / mu; at this time, chemical fertilizers can be applied, and the amount of chemical fertilizers is determined by the corn variety and soil conditions;

[0020] S27: Apply foliar fertilizer:

[0021] In the middle and late stages of crop growth, spray foliar protection 1-2 times, 500 ml / mu each time, diluted with 5 kg of water, and sprayed by drone;

[0022] Other farming operations and cultivation measures (such as tillage, weeding, growth control, watering, and pest and disease control) can be implemented by farmers themselves or following the advice of experts.

[0023] S28: After the crops are harvested, the straw is crushed and returned to the field, and 1-2 tons / mu of high-nitrogen organic liquid fertilizer is sprayed, and 5 kg / mu of straw decomposition agent is added; then the soil is plowed to promote the decomposition of the straw and quickly increase the soil organic matter;

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

[0025] Depending on the actual situation, no or less organic fertilizer may be applied; crops (such as corn) may be planted according to the aforementioned method; after the crops are harvested, the straw may be crushed and returned to the field, 1-2 tons / mu of high-nitrogen organic liquid fertilizer may be sprayed, and 5 kg / mu of straw composting agent may be added; then the soil may be plowed to promote straw decay 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 decomposed at high temperature and then a microbial agent that stimulates plant resistance to salt and alkali is added, with a content of 1 million / g;

[0027] Liquid microbial organic fertilizer is: liquid that has been harmlessly treated, such as biogas slurry, culture medium for the production of monosodium glutamate fermentation, etc., with added microbial agents that stimulate plant resistance to salt and alkali, with a content of 1 million CFU / ml. (CFU, Colony Formation Unit, means the number of viable bacteria).

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

[0029] In the above technical solution, in step S24, the seedling protection is in liquid form, 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 improve plant resistance to salt and alkali.

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

[0031] In the above technical scheme, in step S25, the preparation method of microbial liquid organic fertilizer is: to the harmlessly treated liquid (such as biogas slurry, culture medium waste liquid from monosodium glutamate fermentation production, etc.), add a microbial agent that stimulates plant resistance to salt and alkali, the content of which is 1 million CFU / ml, and the pH is ≤7.0.

[0032] In the above technical solution, the leaf surface protection is a liquid dosage form, the carrier is water, and it contains 1 billion CFU / ml of antagonistic microorganisms that inhibit leaf diseases, 0.5% KH2PO4, 1% urea, and 0.1% agricultural spreader.

[0033] In the above technical scheme, in step S28, the preparation method of high nitrogen organic liquid fertilizer and straw decomposing agent is: using 5% nitrogen amino acid liquid fertilizer as a carrier, adding 1 billion CFU / ml Bacillus subtilis and 100 million CFU / ml ammonia bacteria. High nitrogen organic liquid fertilizer is intended to adjust the C / N ratio of straw to make it easy to decompose, and straw decomposing agent accelerates the decomposition of straw, so that it quickly turns into organic matter to improve soil structure.

[0034] The present invention has the following advantages:

[0035] (1) It is green, environmentally friendly and pollution-free. It can effectively improve the physical and chemical properties of soil and the soil microecological environment, 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) The present invention uses agricultural microorganisms as the main technology for improving saline-alkali land, combined with other conventional measures (such as tillage, weeding, growth control, watering, 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 farmland, and break through the bottleneck of traditional saline-alkali land improvement technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a diagram of enzyme activity in saline-alkali soil 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 of the relative abundance of bacteria and fungi in saline-alkali land at different times 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 saline-alkali land microbial community structure (OTU level) and physicochemical properties 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 test site and the control group in Example 1 of the present invention.

[0043] Figure 7 This is the original landform map of the test field in Example 2 of the present invention.

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

[0045] Fig. 9 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0046] The following is a detailed description of the implementation of the present invention in conjunction with the accompanying drawings, but they do not constitute a limitation of the present invention and are only given as examples. At the same time, the advantages of the present invention are made clearer and easier to understand through the description.

[0047] Example

[0048] The present invention is now described in detail by taking the application of the present invention to a saline-alkali wasteland for soil improvement as an example, which also has a guiding role in the application of the present invention to other saline-alkali wastelands for soil improvement.

[0049] Example 1: Demonstration test of using the present invention to improve soil and plant corn on saline-alkali wasteland in a certain farm

[0050] In this embodiment, a farm in a certain place (N 38°45′; E 106°11′, 1065m above sea level) is located at the foot of a certain mountain in the east, belonging to the arid and semi-arid area of ​​northwest China, with an average annual temperature of 9.0°C, an average annual precipitation of 212mm, and an average annual evaporation of about 1500mm, with precipitation mostly concentrated in June-September. The farm's experimental land is about 50 mu, which is abandoned because crops do not grow. It is a saline-alkali land that has not been plowed for many years, sandy loam, insufficient soil fertility, and hardened texture.

[0051] Saline-alkali wasteland refers to uncultivated saline-alkali land with extremely low soil organic matter, 0.6-1.2% total soluble salt and pH of about 8-9. The salt-alkali resistance of general corn varieties is about 0.3-0.4%, and they can hardly grow on saline-alkali wasteland.

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

[0053] Corn will be planted on saline-alkali wasteland on a farm from 2022 to 2023. The experiment started in mid-to-late March 2022. After an overview survey and assessment of the saline-alkali wasteland, a site was selected (as the test site of the present invention). Deep plowing of the wasteland was carried out 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 applied to the soil, and a basic flora of salt-alkali resistant microorganisms was established in the raw saline-alkali soil. At the same time, the applied liquid organic fertilizer can support the survival and reproduction of microorganisms, forming a dominant flora in the soil, allowing corn (the corn variety is "Dika 159") to grow successfully in saline-alkali land. The planting pattern is the same for the two years, and the specific operations include:

[0054] (1) Mixing seeds with "alkali resistance" powder before sowing: Mix seeds with "alkali resistance" powder (3g / kg seeds) when sowing in early May to form a high concentration of salt-alkali resistant microbial community on the seed surface;

[0055] (2) After sowing, drip irrigation is used to ensure the emergence of seedlings. 1 to 2 kg / mu of seedlings can be drip-irrigated to form a medium concentration of salt- and alkali-resistant microbial flora in the soil around the seeds.

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

[0057] (4) Topdressing: In mid-June, drip irrigation was applied with 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 irrigation was applied with 20 kg / mu of "microbial organic liquid fertilizer" and 7 kg / mu of compound fertilizer; in early July, drip irrigation was applied with 30 kg / mu of "microbial organic liquid fertilizer" and 7 kg / mu of compound fertilizer; in mid-July, drip irrigation was applied with 40 kg / mu of "microbial organic liquid fertilizer" and 10 kg / mu of compound fertilizer; in late July, 12 kg / mu of compound fertilizer.

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

[0059] The method of the present invention is a method for improving the soil of saline-alkali abandoned land, which is a "3+1" salt-alkali resistant series of microbial agents and organic fertilizer application method, comprising: mixing seeds with "alkali resistance" powder before sowing (1); drip irrigation for "seedling protection" after sowing (2); drip irrigation for "microbial organic liquid fertilizer" during the growth period (3); and spraying "foliar protection" (+1) in the middle and late stages of growth; the "3+1" salt-alkali resistant series of microbial agents and organic fertilizer application method of the present invention can effectively ensure the healthy growth of corn in saline-alkali land, and is a "3+1" model for microorganisms to improve plant salt-alkali resistance.

[0060] The alkali resistance, seedling protection, microbial organic liquid fertilizer, foliar protection, and microorganisms that stimulate plant resistance to salt and alkali (i.e., microorganisms that improve plant resistance to salt and alkali) in this embodiment are all commercially available products.

[0061] The control group did not improve the saline-alkali wasteland soil, and directly planted corn on the saline-alkali wasteland in the same area as the test site of the present invention. The corn variety was "Dika 159", and compound fertilizer was applied during sowing, base fertilizer, and topdressing.

[0062] In 2023, the first planting was carried out using the method of the present invention to plant corn, and the corn variety was "Dika 159". Figure 6 As shown in Figure b, Figure 6 Figure b in the figure is a diagram showing the effect of planting corn in the saline-alkali land test site in Example 1 of the present invention) The emergence rate was 85%, the seedling survival rate at maturity was 79%, and the corn yield was 505 kg / mu; the control group (such as Figure 6 As shown in Figure a, Figure 6 Figure a in the figure is a diagram showing the effect of planting corn in the control group of saline-alkali land in Example 1 of the present invention. The emergence rate is 15%, the seedling survival rate at maturity is 5%, and the corn yield is 5 kg / mu. When the corn is harvested, the corn stalks are crushed and returned to the field.

[0063] In the second planting in 2023, corn was planted using the method of the present invention, and the corn variety was "Dika 159". The germination rate of the test field of the present invention was 90%, the seedling survival rate at maturity was 85%, and the corn yield was 658 kg / mu; the germination rate of 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 as follows:

[0065] (1) Sample collection

[0066] Soil samples were collected 4 times within two years of planting corn in saline-alkali wasteland, and the soil was accurately collected from the surface and 20 cm below. The sampling method was the "five-point sampling method" with 3 replicates in each sample area. There were 4 soil treatments. The first saline-alkali wasteland soil sample was collected before sowing in April 2022, which was the original sample (NS0); the second soil sample was collected after the corn was harvested in October 2022 (NS1); the third soil sample was collected before sowing in April 2023 (NS2); the fourth soil sample was collected after the corn was harvested in October 2023 (NS3), and was quickly taken back to the laboratory and stored in a -20℃ refrigerator. After collection, the soil samples were mixed and sieved through 0.25mm, 1mm, and 2mm sieves. Each treatment was repeated 3 times, and the fresh soil samples and air-dried soil samples were tested as required.

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

[0068] 2.1 Effects of microbial fertilizer on the physical and chemical properties of saline-alkali soil

[0069] The physical and chemical properties of saline-alkali soil at different times after the application of microbial fertilizer showed certain differences (as shown in Table 1). The soil pH and EC (electrical conductivity, the greater the conductivity, the higher the salt content) at harvest (NS1 and NS3) within two years showed a significant downward trend compared with the sowing time (NS0 and NS2); OM (organic matter), DOC (soluble carbon), AN (available nitrogen), AP (available phosphorus) and AK (available potassium) all increased significantly compared with before sowing, but DOC and AK decreased at the harvest time of the second year; Mg among the eight main ions in the soil 2+ , SO4 2- and HCO3 - Both showed a downward trend, K + , Na + With Cl - It increased after the first year of harvest and decreased significantly in the second year. 2+ It increased significantly in NS1 and NS3. It is worth noting that no CO3 was detected in the four soil samples tested. 2- This indicates that the microbial fertilizer in the present invention can reduce soil pH, EC and the content of some ions harmful to crop growth, increase the content of substances such as OM, AN and AP that are beneficial to crop growth, and has a good trend in improving saline-alkali land.

[0070] Table 1 Physical and chemical properties of saline-alkali soil at different times after applying salt-alkali resistant microbial fertilizer

[0071]

[0072]

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

[0074] like Figure 1As shown, compared with the original soil before sowing in the first year, the application of the microbial fertilizer of the present invention can significantly improve the urease activity, soil alkaline phosphatase activity and sucrase activity of saline-alkali soil after two years, and the activity rankings are NS3>NS2>NS1>NS0, NS3>NS2>NS1>NS0 and NS3>NS1>NS2>NS0, respectively. The soil samples collected at harvest two years later showed the highest activity of these three enzymes compared with other periods, among which the soil urease activity NS3 increased by 90.18% compared with NS0, the soil alkaline phosphatase activity NS3 increased by 45.67% compared with NS0, and the sucrase activity NS3 increased by 82.31% compared with NS0. The trend of soil catalase activity is opposite to that of the other three enzyme activities, and the activity rankings are NS2>NS0>NS3>NS1, respectively. The soil catalase activity at each harvest is lower than that before sowing. This result shows that the microbial fertilizer of the present invention can improve the soil enzyme activity that is beneficial to the improvement of saline-alkali land and reduce the unfavorable soil enzyme activity, showing a positive correlation trend.

[0075] exist Figure 1 In the table, Urease refers to urease in saline-alkali soil; Alkaline phosphatase refers to alkaline phosphatase; Sucrose refers to sucrase; Catalase refers to catalase. Figure 1 Where a represents urease activity, b represents alkaline phosphatase activity, c represents sucrase activity, and d represents catalase activity.

[0076] 2.3 Analysis of Alpha Diversity of Soil Microbial Communities in Saline-Alkali Land Treated with Salt-Alkali-Resistant Microbial Fertilizer

[0077] By using the Illumina Miseq PE300 platform to sequence soil DNA at different periods, the sample library coverage rate was above 98%, indicating that the sequencing depth can cover most of the microorganisms in the soil and can truly reflect the microbial community information in each sample. Table 2 shows the results of the Alpha diversity index of the sequenced soil samples. The Ace, Chao and Sobs indices represent species richness, and the larger the value, the higher the species richness; the Shannon and Simpson indices reflect the diversity of species. The larger the Shannon index, the smaller the Simpson index, and the higher the species diversity. This embodiment uses the method of the present invention to improve the soil. The Ace, Chao and Sobs indices of soil bacteria at the harvest period within two years are significantly higher than those before sowing. NS3 has the highest species richness and NS0 has the lowest; the soil Shannon and Simpson indices are also more significant in soils at different periods, with the Shannon index showing an upward trend and the Simpson index showing the opposite result. Compared with the richness and diversity of soil bacterial communities at different periods, the Simpson index of fungi was not significantly different, but the Shannon, Ace, Chao and Sobs indices of soil fungi at the harvest period within two years were significantly higher than those before sowing, with NS3 being the highest and NS0 being the lowest. This indicates that the application of the microbial fertilizer of the present invention can improve the richness and diversity of soil bacteria and fungi in saline-alkali land.

[0078] Table 2 Results of saline-alkali land microbial diversity index

[0079]

[0080] 2.4 Analysis of the community structure and composition of microbial fertilizers in saline-alkali soil microorganisms

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

[0082] The number of soil bacteria and fungi OUT (operational classification unit) in four periods within two years after applying 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 in four periods, of which NS3 had the largest number of OTUs, 5414, and NS0 had the least, 2643. Analysis of the Venn diagram found that there were 1743 OTUs in common among the four groups of samples, accounting for 19.73%. The number of OTUs specific to NS0, NS1, NS2, and NS3 were 638, 737, 783, and 1293, respectively, accounting for 7.22%, 8.34%, 8.86%, and 14.64%, respectively. NS3 had the highest proportion, and NS0 had the lowest, as shown in Figure 2As shown in Figure a. In the Venn diagram of fungi, a total of 896 fungal OTUs were obtained from soil samples collected in four periods, of which NS3 had the largest number of OTUs, 492, and NS0 had the least, 266. Analysis of the Venn diagram found that there were 68 OTUs in common among the four groups of samples, accounting for 7.59%. The number of OTUs unique to NS0, NS1, NS2, and NS3 were 102, 106, 127, and 231, respectively, accounting for 11.38%, 11.83%, 14.17%, and 25.78%, respectively. NS3 had the highest proportion, and NS0 had the lowest, as shown in Figure 2. Figure 2 The results show that the number of OTUs of soil bacteria and fungi increased significantly within two years after the application of microbial fertilizer, and the number, richness and diversity of microbial species were improved during the improvement of saline-alkali land.

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

[0084] The community composition of soil bacteria at the phylum level was significantly different in different periods. The 10 bacterial phyla with the highest relative abundance were Proteobacteria, Actinobacteriota, Chloroflexi, Bacteroidota, Firmicutes, Acidobacteriota, Gemmatimonadota, Myxococcota, Patescibacteria, and Cyanobacteria. The dominant bacterial phyla were Proteobacteria, Actinobacteria, and Chloroflexi, accounting for more than 70% of the relative abundance of the total bacterial community. The relative abundance of Proteobacteria increased significantly in NS1 and NS3 during the two harvest periods. The relative abundance of Actinobacteria decreased step by step in the four periods. The proportion of Chloroflexi in each period did not change much. It is worth noting that the relative abundance of Acidobacteria increased continuously in the four periods (such as Figure 3 (as shown in Figure a).

[0085] At the fungal phylum level, the main dominant community was Ascomycota, which had the highest relative abundance, accounting for 80%-95% of the total community. The proportion was high in all periods, and it decreased in NS3. The relative abundance of Basidiomycota increased in NS3, but Chytridiomycota appeared in NS1 and NS3 during the two harvest periods, and was not found in NS0 and NS2 during the two sowing periods (e.g. Figure 3 (as shown in Figure b).

[0086] The results showed that the application of microbial fertilizer had a significant effect on the Proteobacteria and Acidobacteria of the bacterial community within two years, and had a good improvement effect on saline-alkali land; the application of microbial fertilizer led to the emergence of Chytridiomycota in the fungal community, which may also play a certain role in the improvement of 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 periods

[0089] In the bacterial Circos at the phylum level, the dominant species in the samples of the four periods were all Actinobacteria, Proteobacteria and Chloroflexi. In the first year of sowing period, the largest proportion of NS0 samples was Actinobacteria, accounting for 38%-41%, Proteobacteria accounted for 25%, and Chloroflexi accounted for 9%. In the harvest period of NS1, the proportions of Proteobacteria and Actinobacteria were both about 30%, and Chloroflexi accounted for 11%. Compared with NS0, the proportions of Proteobacteria and Chloroflexi in NS1 increased. In the second year of sowing period, Proteobacteria were 30%, Actinobacteria were 27%, and Chloroflexi accounted for 10%. The proportions of Actinobacteria and Chloroflexi in NS2 decreased; in the harvest period of NS3, Proteobacteria accounted for 35%-38%, the largest proportion, Actinobacteria accounted for 19%, and Chloroflexi accounted for 10%-13%. Compared with before sowing, the proportions of Proteobacteria and Chloroflexi increased, and the proportion of Actinobacteria decreased. In general, the improvement results of saline-alkali land by applying microbial fertilizer for two years showed that the proportion of Proteobacteria increased, the proportion of Actinobacteria decreased, and the proportion of Chloroflexi did not change much, which was not the key factor affecting species.

[0090] In the phylum-level fungal Circos, the dominant species in the samples of the four periods were Ascomycota, which accounted for the largest proportion, followed by Basidiomycota. The proportion of Ascomycota in the NS0 sample was the largest at 97%, and then decreased in NS1, NS2, and NS3, reaching 87% in NS3; Basidiomycota increased slightly, from 2% in NS0 to more than 6% in NS3. In general, the application of microbial fertilizer reduced the Ascomycota in saline-alkali land, increased the Basidiomycota, and changed the species ratio of the fungal community. There are many plant pathogens in the Ascomycota, and the Basidiomycota are basically non-pathogenic bacteria.

[0091] 2.5 Analysis on the difference of soil microbial community structure in saline-alkali land by microbial fertilizer

[0092] PCA analysis, i.e. principal component analysis, was performed on the OTU data of bacteria and fungi. The results are as follows Figure 4As shown, in the principal component analysis of bacteria and fungi, the three samples of the same treatment were close to each other, with good repeatability, and the treatments of the four periods had a certain distance, indicating that there were certain differences between the samples. In the principal component analysis of bacteria, the contribution rates of PC1 and PC2 were 21.72% and 15.61%, respectively. The NS2 and NS3 groups were clearly distinguished from the NS0 and NS1 groups along PC1. In the PC2 analysis, the NS0, NS1, NS2, and NS3 groups were all clearly distinguished, indicating that there were large differences in microorganisms between the groups. The distance between the NS0 and NS1 groups in PC1 was not obvious, and the difference was small, as shown in Figure 2. Figure 4 As shown in Figure a ( Figure 4 The horizontal axis is the principal component 1 with large variance, and the vertical axis is the principal component 2 with small variance. The closer the distance, the more similar the microbial composition. In the principal component analysis of fungi, the contribution rates of PC1 and PC2 were 17.58% and 12.51%, respectively. In the PC1 analysis, the distance between the NS3 group and the NS0 group, NS1 group, and NS2 group was obvious, and the microbial differences between the groups were large. However, the distance between the NS0 group, NS1 group, and NS2 group was not obvious, and the difference was small. In the PC1 analysis, the NS0 group, NS1 group, NS2 group, and NS3 group all had a certain distance, and there were certain differences between the groups, such as Figure 4 As shown in Figure b.

[0093] Therefore, whether it is the principal component analysis of bacteria or fungi, there is a certain distance between the treatments in the PC1 and PC2 analysis, and the distance indicates that the microbial differences between the groups are large, indicating that the application of microbial fertilizer in saline-alkali soil improvement has a great impact on soil microbial diversity.

[0094] 2.6 Correlation analysis between microbial fertilizer and physical and chemical properties of saline-alkali soil and microbial community

[0095] The RDA analysis was used to study the effects of soil physical and chemical properties on the bacterial community structure of saline-alkali soil at different periods after the application of microbial fertilizer in saline-alkali land. In the RDA community, the combination of RDA1 and RDA2 variables explained 91.27% of the variation in bacterial communities and 69.82% of the variation in fungal communities (e.g. Figure 5 As shown, Figure 5 The RDA (Redundancy Analysis) redundancy analysis in the paper is to determine the correlation between the structural characteristics of the microbial community and the environmental physical and chemical factors. The percentage in the brackets of the coordinate axis represents the proportion of the difference in the original database that can be explained by the corresponding coordinate axis. Figure 5 Each point in the graph represents a sample. The closer the distance between two points, the higher the similarity of the microbiomes of the two samples. Figure 5The middle arrows represent environmental physicochemical factors. The smaller the angle between the arrows, the greater the correlation between them. A right angle means no correlation, and an obtuse angle means 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 the bacterial community is AP>EC>pH>OM>AN>DOC>AK. Before the application of microbial fertilizer (NS0), it was significantly positively correlated with soil EC and pH, and significantly negatively correlated with AP. After the application of microbial fertilizer (NS0), the results were opposite. Figure 5 As shown in Figure a. Soil AP, AK and DOC are the main factors affecting the fungal community. The influence of each physical and chemical factor on the bacterial community is AP>AK>DOC>pH>EC>AN>OM. Before the application of microbial fertilizer (NS0), it was significantly positively correlated with soil EC and significantly negatively correlated with AP. After the application of microbial fertilizer (NS0), the results were opposite. Figure 5 As shown in Figure b. It can be seen that AP has a greater impact on soil microbial communities after the application of microbial fertilizers, and plays an important role in the improvement of saline-alkali land.

[0096] Conclusion: After the above tests, we found that:

[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 harmful physical and chemical factors and ion content, and improve the improvement effect of saline-alkali soil;

[0098] With the improvement of saline-alkali wasteland by applying microbial fertilizer, the internal environment of the soil changes, which in turn affects the physical and chemical properties of saline-alkali soil. The present invention analyzed and found that the physical and chemical properties of the soil after improvement of the saline-alkali wasteland in a farm in this embodiment were significantly different (as shown in Table 1). The soil pH and EC showed a decreasing trend with the improvement time. The decrease in soil pH and EC increased OM, AN and AP in the soil, indicating that high pH and EC would affect the utilization of OM, AN and AP in the soil by plants. Studies have shown that the application of microbial agents can increase the soil desalination rate, because some beneficial microorganisms in saline-alkali land can produce polysaccharides and mucilages during their activities to form soil binders, affect the aggregate structure, reduce bulk density and soil non-capillary pores, thereby accelerating soil salt leaching and reducing soil salt content. This is consistent with the Mg content of the eight main ions in the soil in the test site of the present invention. 2+ 、SO4 2- and HCO3 - Both showed a downward trend, Ca 2+ Significantly increased at harvest, K + 、Na + With Cl -The results are consistent, with an increase after the first year's harvest and a significant decrease in the second year. Microbial fertilizers activate native soil microorganisms and use the organic matter rich in microbial fertilizers to provide more nutrition for soil microorganisms, thereby increasing the number of microorganisms. Soil enzymes, as a link between plants and nutrients, can not only objectively reflect the fertility of the soil, but also indirectly affect the circulation of nutrient elements 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. The urease, alkaline phosphatase and sucrase activities of the soil in the harvest period after the application of microbial fertilizers in the test site of the present invention are all higher than the soil activity before sowing. Because the application of biological agents can accelerate the decomposition rate of organic matter in the soil on the one hand, it provides 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 in the test plot of the present invention has a downward trend at harvest, mainly because the soil microecological environment has changed after the application of microbial fertilizer, the saline-alkali stress has been alleviated, and the content of hydrogen peroxide harmful to plants has been reduced. Overall, the application of microbial fertilizer has increased the soil nutrient content and enzyme activity of saline-alkali wasteland, reduced some harmful physical and chemical factors and ion content, and has 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] The diversity and relative abundance of soil microorganisms are important indicators for measuring soil fertility. Increasing the number of beneficial microorganisms in the soil can effectively promote the growth and development of plants. The application of microbial fertilizers not only promotes the formation of new microbial communities around plant roots, but also improves the ecological environment of the soil. The test results of the experimental field of the present invention show that with the application of microbial fertilizers to improve saline-alkali wasteland, the Ace, Chao and Sobs indexes of soil bacteria and fungi in the harvest period within two years are significantly higher than before sowing, NS3 has the highest species richness, and NS0 has the lowest; the soil Shannon and Simpson indexes of soil samples at different periods are also more significant, the Shannon index shows an upward trend, and the Simpson index of bacteria decreases, 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 (Ascomycota) and Basiodiomycota (Basidiomycota) in the fungal community dominate in all soils. Proteobacteria, Acidobacteriota, Bacteroidota and Actinobacteriota were the dominant groups of soil bacteria in farmland. Microbial agents changed the relative abundance of some groups to a certain extent. In the test site of the present invention, the proportion of bacterial and fungal OTU in the soil samples was the highest at the harvest of the second year of improvement. The proportion of community composition in each period at the phylum level had different dynamic changes. The dominant bacterial phyla were Proteobacteria, Actinobacteria and Chloroflexi, accounting for more than 70% of the relative abundance of the total bacterial community. The relative abundance of Proteobacteria increased significantly in both harvest periods, the relative abundance of Actinobacteria decreased step by step in each period, and Chloroflexi had little effect. It is worth noting that the relative abundance of Acidobacteria increased continuously in the four periods, and it is speculated that it may be an important factor in the decrease of soil pH; the dominant fungal community was Ascomycota, and the relative abundance proportion in each period was the highest. The relative abundance proportion of Basidiomycota increased when the second year was harvested, and Chytridiomycota appeared in the two harvest periods. The species diversity and richness of fungi at the phylum level were lower than those of bacteria. The test results of the test site of the present invention show that the application of microbial fertilizer in the improvement of saline-alkali soil has a certain effect on the Acidobacteria of bacteria and the Chytridiomycota appearing in fungi, and may also play a key role in the improvement of saline-alkali soil.

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

[0102] The structure of soil microbial communities is closely related to the soil environment. The improvement mode will cause changes in the physical and chemical properties of the soil, thereby changing the structure of the soil microbial community. The type of soil mainly depends on the composition of the microbial community or is affected by the complex interaction between the soil and plants. Microbial fertilizers can improve soil fertility by changing the microbial community structure of the rhizosphere soil. In the PCA analysis of the OTU data of bacteria and fungi in the test field of the present invention, it was found that the contribution rates of bacterial PC1 and PC2 were 21.72% and 15.61%, respectively, and the contribution rates of fungal PC1 and PC2 were 17.58% and 12.51%, respectively. There was a certain distance between each treatment in the PC1 and PC2 analysis, and the distance indicated that the microbial differences between the groups were large, indicating that the application of microbial fertilizers in saline-alkali soil improvement had a great impact on soil microbial diversity. Redundancy analysis (RDA) can be used to describe the relationship between soil physical and chemical 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 in the test field detection of the present invention shows that AP, EC and pH value in the soil physical and chemical properties are the main factors determining the bacterial community structure after saline-alkali land improvement, and AP, AK and DOC are the main factors affecting the fungal community structure, indicating that these physical and chemical factors play an important role in the changes of soil microbial communities after the application of the microbial fertilizer of the present invention, and have great potential in the process of saline-alkali land improvement.

[0103] After two years of improvement of saline-alkali wasteland, the experimental site of the present invention significantly reduced soil pH and EC, and increased the contents of physical and chemical properties such as OM, DOC, AN, AP and AK, and Ca 2+ The content increased significantly at harvest, K + 、Na + Mg 2+ 、SO4 2- 、HCO3 - and Cl -The contents of soil urease, alkaline phosphatase and sucrase were all on a downward trend. The activities of soil urease, alkaline phosphatase and sucrase were significantly increased during the harvest period, while the activity of catalase decreased. In addition, after two years of improvement, the diversity of microbial communities was significantly changed, and the number and composition of bacterial and fungal communities in saline-alkali soil were also significantly affected. The three dominant bacterial phyla of bacteria, Proteobacteria, Actinobacteria and Chloroflexi, increased in proportion to Proteobacteria and Chloroflexi after improvement, while the proportion of Actinobacteria decreased. The dominant fungal phylum Ascomycota decreased during the improvement process, and Chytridiomycota appeared in both harvest periods. PCA analysis of bacteria and fungi found that the microbial communities were significantly different during the improvement process. RDA analysis found that the important physical and chemical factors affecting the structure of soil bacterial communities were AP, EC and pH, while those affecting the structure of fungal communities were AP, AK and DOC, indicating that these factors all led to changes in soil microbial communities. The present invention provides a certain scientific basis and data for the improvement of saline-alkali land. In the agricultural production process, the stability of the soil-crop ecosystem can be adjusted by applying the microbial fertilizer of the present invention to reduce the degree of salt-alkali stress.

[0104] Example 2: Demonstration test of using the present invention to improve soil and plant corn on saline-alkali abandoned land in a certain county

[0105] Basic information of the experimental field: The experimental plot is located in Disiya Village, Wushijia Town, a certain county, with an alluvial fan plain topography. The soil is highly sticky and has a low water permeability. The tillage layer is severely compacted and the surface is white (such as Figure 7 shown).

[0106] Saline-alkali wasteland refers to uncultivated saline-alkali land with extremely low soil organic matter, 0.6-1.2% total soluble salt and pH of about 8-9. The salt-alkali resistance of general corn varieties is about 0.3-0.4%, and they can hardly grow on saline-alkali wasteland.

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

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

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

[0110] (4) Natural vegetation: perennial salt-tolerant plants such as bitter bean, reed, and sheep fescue, and significant alopecia areata.

[0111] (5) Experimental group: using the method of the present invention to improve the soil of saline-alkali abandoned land (i.e. using "3+1" salt-alkali resistant series of microbial agents and organic fertilizers);

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

[0113] The trial will begin in 2024, and the trial group (such as Figure 8 The seedling emergence rate of the plot (as shown in the right figure in the figure) reached 80%, and there was no rigid seedling phenomenon. The performance of corn seedlings was close to that of good farmland soil. Figure 8 The germination rate (as shown in the left figure) is 6%, and there are many rigid seedlings.

[0114] At present, the commonly used saline-alkali land classification index is: soil with a salt content of 1 to 3‰ is light saline-alkali land; soil with a salt content of 3 to 6‰ is moderate saline-alkali land; soil with a salt content of 6 to 9‰ is severe saline-alkali land. Soil with a salt content exceeding 9‰ is difficult to develop and utilize. The current test results show that the new saline-alkali land improvement method with microorganisms as the core of the present invention can be used for the development and utilization of saline-alkali wasteland with a salt content of 11.5‰, and is also suitable for the improvement of moderate and severe saline-alkali land. The present invention can effectively improve the physical and chemical properties of soil and the soil microecological environment, and plays 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] Other parts not described belong to the prior art.

Claims

1. A method for improving saline-alkali wasteland based on agricultural microorganisms, characterized in that: The following steps are included: Step 1: site selection, confirming that the saline-alkali wasteland to be improved meets the improvement requirements; Step 2: Use a two-year planting model to improve saline-alkali wasteland. Specific operations include: S21: Apply solid and / or microbial liquid organic fertilizer in the autumn of the first year, 5-20 tons / mu, evenly spread or spray, and then till the land; S22: Level the land again before sowing in spring to break up large clumps of soil into fine particles; S23: Mix seeds with alkali-resistant powder agent before sowing; S24: After sowing, drip irrigation is used to ensure seedling emergence, and the seedling emergence protection is 1-2 kg / mu; S25: Apply base fertilizer: Apply compound fertilizer 45% nutrient 20kg / mu before plowing; S26: Applying topdressing: After the crops emerge, when the seedlings are about 7-12 cm tall, drip irrigation of microbial liquid organic fertilizer 10 kg / mu is applied; When the seedling height reaches 15-20 cm, the second drip tank is used to apply 20 kg / mu of microbial liquid organic fertilizer and 7 kg / mu of compound fertilizer; When the seedling height reaches 30-40 cm, the third drip tank microbial liquid organic fertilizer is 30 kg / mu and compound fertilizer is 7 kg / mu; The fourth drip tank of microbial liquid organic fertilizer is 40 kg / mu and compound fertilizer is 10 kg / mu when the seedling height is 50-70 cm; S27: Apply foliar fertilizer: In the middle and late stages of crop growth, spray foliar protection 1-2 times, 500 ml / mu each time, diluted with 5 kg of water; S28: After the crops are harvested, the straw is crushed and returned to the field, 1-2 tons / mu of high-nitrogen organic liquid fertilizer is sprayed, and 5 kg / mu of straw composting agent is added; then the soil is plowed and turned 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, ensuring that the roots of the crops to be planted are above the groundwater; 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: In step S23, the carrier of the alkali-resistant powder agent is 300 mesh humic acid powder, containing 200 million CFU / g of microorganisms that improve plant resistance to salt and alkali, and the moisture content of the alkali-resistant powder agent is 8-10%; The method of mixing seeds with alkali-resistant powder agent is: 3 grams / kg 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 decomposing bacteria agent is: using 5% nitrogen-containing amino acid liquid fertilizer as a carrier, adding 1 billion CFU / ml Bacillus subtilis and 100 million CFU / ml ammonia bacteria.

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