A black soil improvement method combining furrow application of manure and microbial agent with returning straw to the fields

Abstract

The present invention discloses a method for improving black soil by applying a manure fertilizer in a furrow combined with returning straw to the field. The method comprises the following steps: returning straw to the field: after harvesting the previous crop, crushing the previous crop straw and returning it to the field; preparing a composite inoculant: inoculating psychrophilic bacteria, cellulolytic bacteria, and anaerobic bacteria into LB culture medium to form a bacterial solution, diluting the bacterial solution 20-100 times, mixing them in a volume ratio of (1-2):(1-2):(1-2), and adding auxiliary materials to prepare a composite inoculant; applying the composite inoculant into the 0-15 cm soil layer through shallow furrows along the planting rows at a dosage of 100-150 kg / mu; and sowing seedling strips in alternate years. The method of the present invention can significantly increase the organic matter content of black soil, improve soil aggregate structure, reduce the salinity of the plow layer, and achieve rapid soil fertilization and stable crop yield and efficiency.

Description

Technical Field

[0001] The invention relates to a black soil protection method in the agricultural field, and in particular to a black soil improvement method combining furrow application of manure and microbial agent with returning straw to the fields. Background Art

[0002] Conservation tillage techniques, primarily based on crop straw mulching and no-till (or minimum-till) seeding, offer significant advantages in preventing black soil degradation and improving soil carbon sequestration and fertility. They have been rapidly adopted in Northeast China in recent years. However, research and practice have revealed that long-term, continuous straw mulching also leads to a series of problems, including low decomposition rates of accumulated straw in the surface layer, slow soil warming, and low crop emergence rates. These issues limit the technology's potential for carbon sequestration, fertilization, and crop yield increases.

[0003] Functional microorganisms are the core driving force for promoting the rapid decomposition of manure and straw and the cultivation of healthy black soil. Soil microbiome manipulation has been successfully applied to change the composition of microbial communities in the soil-plant system, and has achieved remarkable results in increasing crop productivity and improving plant and human health. In the black soil region of Northeast China, the low temperature and drought climate and low soil accumulated temperature have slowed down the decomposition rate of straw mulching and returning to the field. In addition, the surface enrichment caused by large-scale straw mulching for many years has affected the carbon conversion efficiency of straw to soil. Screening functional microorganisms to develop microbial preparations and regulating the soil environment to cultivate soil microorganisms in a targeted manner are the preferred ways to improve the health of soil and crops. The basic theories and technologies of black soil fertility under the conditions of conservation tillage straw mulching are in urgent need of breakthroughs. At present, the understanding of the targeted regulation process and mechanism of microbial functions in the black soil conservation tillage straw mulching technology is very limited. Summary of the Invention

[0004] Aiming at the problems of low manure utilization efficiency, poor straw return effect, and difficulty in ensuring sowing quality during black soil planting, the present invention proposes a black soil improvement method that combines furrow application of manure and microbial agents with returning straw to the fields.

[0005] The black soil improvement method provided by the present invention comprises the following steps:

[0006] Straw return to the field: After the previous crop is harvested, the straw of the previous crop is crushed and covered between the rows on both sides of the fertilizer strip in a strip width of 60-75 cm, leaving a 40-45 cm bare area in the seedling strip;

[0007] Preparation of composite bacterial agent: psychrophilic bacteria, cellulolytic bacteria, and anaerobic bacteria are inoculated into LB culture medium to form bacterial liquid, the bacterial liquid is diluted 20-100 times, mixed in a volume ratio of (1-2): (1-2): (1-2), and auxiliary materials are added to prepare composite bacterial agent;

[0008] The compound bacterial agent is applied into the 0-15 cm soil layer by digging shallow trenches along the planting rows, with the dosage of the compound bacterial agent being 100-150 kg / mu;

[0009] Seedling strip sowing is alternated every other year: when sowing in the next year, the position of the seedling strip is adjusted to the straw covering strip of the previous year, and the original seedling strip is converted to the new covering strip, with an alternation cycle of 2 years; wide and narrow rows are used in conjunction, with wide rows of 60~75 cm as the covering area and narrow rows of 40~45 cm as the seedling strip; in wide and narrow row planting, the narrow row seedling strip is directly sown through the stubble, with a sowing depth of 3-5 cm.

[0010] Preferably, the previous crop straw is shredded to a length of 5-8 cm.

[0011] Preferably, the method further comprises the step of applying the composite bacterial agent in combination with manure; the mass ratio of the manure to the composite bacterial agent is (1-1.5): (15-17).

[0012] Preferably, the manure and the composite bacterial agent are shallowly applied into the 0-15 cm soil layer by digging trenches.

[0013] Preferably, the step of inoculating the psychrophilic bacteria, cellulolytic bacteria, and anaerobic bacteria into LB culture medium to form a bacterial solution comprises: inoculating the psychrophilic bacteria, cellulolytic bacteria, and anaerobic bacteria into LB liquid culture medium at an inoculum rate of 1-5% by volume, respectively; wherein the cellulolytic bacteria and the anaerobic bacteria are shaken and cultured at 15-20° C. and 150-180 r / min for 1-3 days to form a bacterial solution of the cellulolytic bacteria and a bacterial solution of the anaerobic bacteria, respectively; and the psychrophilic bacteria are cultured at a low temperature of 0-10° C. and shaken at 150-180 r / min for 1-3 days to form a bacterial solution of the psychrophilic bacteria.

[0014] Preferably, the auxiliary material comprises: 1-5 mg / ml of sugar as a protective agent, 0.5-3 mg / ml of nitrogen source, and 0.01-0.1 mg / ml of vitamins.

[0015] Preferably, the excipient comprises the following components: 3.0 mg / ml trehalose as a protective agent, 1.5 mg / ml yeast extract powder as a nitrogen source, and 0.035 mg / ml vitamin premix; the vitamin premix contains 0.02 mg / ml thiamine, 0.01 mg / ml pyridoxine, and 0.005 mg / ml riboflavin.

[0016] Preferably, the bacterial solutions of the psychrophilic bacteria, the cellulolytic bacteria, and the anaerobic bacteria are mixed in a volume ratio of 1:1.5:1 to 1:2:1.

[0017] Preferably, the bacterial solutions of the psychrophilic bacteria, the cellulolytic bacteria and the anaerobic bacteria are mixed in a volume ratio of 1:2:1.

[0018] Preferably, after diluting the bacterial solution 20-100 times, the bacterial content in the bacterial solution is greater than 10 9 CFU / g.

[0019] Preferably, the mixture of the composite bacterial agent and the auxiliary material is pre-frozen at -80°C for 2 to 4 hours and then transferred to a freeze dryer for freeze-drying or directly packaged in liquid form.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) Rapid fertilization: Manure and microbial agents synergistically increase the mineralization rate of organic matter. Within two years, soil organic carbon increased by 9.1% and the average weight diameter of water-stable aggregates increased by 8.9%.

[0022] (2) Resource efficiency: Straw strip mulching reduces straw usage by 30% and avoids covering with seedling strips. Alternating straw strips every other year promotes straw decomposition and nutrient release, and the nitrogen absorption of corn increases significantly by 174.9%.

[0023] (3) Planting compatibility: Wide-narrow row design and alternate-year rotation ensured sowing quality, and corn yield increased by 32.0%.

[0024] This method uses shallow application of manure to improve nutrient availability in the root zone, microbial agents to accelerate organic matter decomposition and neutralize salinity, straw mulching to reduce soil evaporation and inhibit surface salt accumulation, and alternate sowing to optimize the soil microenvironment. This method significantly increases the organic matter content of black soil, improves soil aggregate structure, and reduces salinity in the topsoil, achieving rapid soil fertility improvement and stable crop yields and increased efficiency.

[0025] The present invention is based on a soil fertilization and microbial regulation technology system for target habitat transformation. Targeted at the climate and soil characteristics of black soil cold and arid areas, it deeply explores the synergistic efficiency-enhancing approaches of organic resources and biological resources such as organic fertilizers, straw, and microorganisms in fertilizing cultivated land. It innovatively integrates a new soil fertilization model that adapts to organic substitution, straw mulching, and bio-augmentation, and comprehensively constructs a theoretical, methodological, and technical system for improving black soil fertility under protective tillage straw mulching conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] For purposes of illustration and not limitation, the present invention will now be described with reference to preferred embodiments thereof, particularly with reference to the accompanying drawings, in which:

[0027] Figure 1 The invention discloses the field operation steps of the black soil protection method of combining furrow application of manure fertilizer microbial agent with returning straw to the fields.

[0028] Figure 2 Results of the effects of different treatments on maize yield and crop characteristics.

[0029] Figure 3The results of different treatments on soil nutrients. DETAILED DESCRIPTION

[0030] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0031] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0032] Example 1: Black soil improvement method using composite bacterial agent in furrow application

[0033] 1. Preparation method of composite bacterial agent:

[0034] Based on the functions and synergistic effects of the strains, different types of microbial strains were combined in a certain ratio. Psychrophilic bacteria, cellulolytic bacteria, and anaerobic bacteria were inoculated into LB liquid medium at a 2% (v / v) inoculum. Cellulolytic bacteria and anaerobic bacteria were cultured at 18°C ​​with shaking at 160 rpm for 1-3 days to form cellulolytic and anaerobic culture solutions, respectively. Psychrophilic bacteria were cultured at 8°C with shaking at 150 rpm for 1-3 days to form a psychrophilic culture solution. The culture solutions of the different strains were then mixed at a certain volume ratio (see Table 1) and fermented at 18°C ​​with shaking at 160 rpm for 2-3 days to prepare a mixed bacterial suspension. The optimal combination ratio was screened as 1:2:1 for psychrophilic bacteria, cellulolytic bacteria, and anaerobic bacteria by measuring the activity of various cellulases. Psychrophilic bacteria, cellulolytic bacteria, and anaerobic bacteria were purchased from the Culture Collection Center of Ningbo Biotechnology Co., Ltd., with the strain numbers being HZB280107, M3213, and RY-Y-102, respectively.

[0035] Table 1 Determination of enzyme activity of composite bacterial agent

[0036]

[0037] Preparation of microbial agent: dilute the bacterial solutions of psychrophilic bacteria, cellulolytic bacteria and anaerobic bacteria by 20-100 times respectively. The bacterial content in the diluted fermentation solution should be greater than 10 9CFU / g. A composite bacterial solution is prepared by mixing the optimal ratio of psychrophilic bacteria: cellulolytic bacteria: anaerobic bacteria (1:2:1 by volume). During preparation, appropriate excipients are added: 3.0 mg / ml trehalose as a preservative, 1.5 mg / ml yeast extract powder as a nitrogen source, and 0.035 mg / ml vitamin premix (containing 0.02 mg / ml thiamine, 0.01 mg / ml pyridoxine, and 0.005 mg / ml riboflavin) to ensure the stability and activity of the inoculum. The composite bacterial solution-excipient mixture is pre-frozen at -80°C for 2–4 hours and then transferred to a freeze dryer for freeze-drying or packaged directly as a liquid.

[0038] Principle of compounding of bacterial agents: The compound bacterial agent of the present invention is prepared by psychrophilic bacteria ( Pseudomonas psychrophila ), cellulose decomposing bacteria ( Cellulomonas fimi ) and anaerobic bacteria ( Clostridium butyricum ) achieve efficient degradation in low-temperature environments through the spatiotemporal synergistic effect of the following: Psychrophiles (1 / 4): They are the first to start metabolism at low temperatures of 0-10 ℃, secrete low-temperature active enzymes (such as cold-adapted proteases and lipases) to pre-decompose organic matter, and produce extracellular polysaccharides to maintain the temperature of the bacterial microenvironment; Cellulolytic bacteria (2 / 4): In the microenvironment established by psychrophiles, they use the trinity enzyme system of exoglucanase (CBH), endoglucanase (EG) and β-glucosidase (BGL) to break down the cellulose crystal structure of straw; Anaerobic bacteria (1 / 4): Decompose lignin-protein complexes under microaerobic conditions, and the short-chain fatty acids such as butyrate produced by their metabolism can promote the formation of psychrophilic biofilms, while regulating the C / N ratio to the optimal range of (20-25):1.

[0039] 2. Black soil improvement method of compound bacterial agent in furrow application

[0040] The Shenyang field experiment was conducted in Mushu Village, Shenbei New District, Shenyang City, Liaoning Province (42°00' N, 123°27' E). The area has a north temperate continental monsoon climate, with an average annual temperature of 7.50 ~ 8.70 ℃, an annual frost-free period of 147 ~ 164 days, and an average annual precipitation of 755 mm. The annual precipitation fluctuates greatly, and the seasonal distribution is irregular. In 2021, the precipitation was 724 mm, and the precipitation rate from May to October was 84%, mainly concentrated in August and September; in 2022, the precipitation was 500 mm, and the precipitation rate from May to October was 76%, mainly concentrated in June and July. The precipitation in August and September was significantly lower than in previous years, belonging to a relatively dry season. The experimental soil is dark brown soil, and the basic soil properties of 0-20 cm are: organic matter 13.20 g·kg -1 , total nitrogen 1.06 g·kg -1 , alkaline nitrogen 89 mg·kg -1 , available phosphorus 31 mg·kg -1, fast-acting potassium 126 mg·kg -1 , pH 5.61.

[0041] The field trial began in 2021, and five microbial agent treatments were set up: (1) Example of the present invention: 1:2:1 composite microbial agent of the present invention; (2) Comparative Example 1: single cellulose decomposing bacteria; (3) Comparative Example 2: psychrophilic bacteria: anaerobic bacteria = 2:1; (4) Comparative Example 3: commercially available composite microbial agent (microbial agent, purchased from Heilongjiang Heiwotu Biotechnology Co., Ltd.); (5) Control (CK): no microbial agent was applied and straw was not returned to the field (CK). Each treatment area was 2600 m 2 (100 m × 26 m), randomized block design, repeated 3 times. In the Examples of the present invention, Comparative Examples 1, 2, and 3, straw was returned to the field (straw was crushed to 5-8 cm and fully covered on both sides of the fertilizer strip in a strip width of 40-50 cm, leaving 20-30 cm of the seedling strip exposed). The microbial agent was applied at a dosage of 100 kg / mu, and applied into the 0-15 cm soil layer in shallow furrows along the planting rows. Corn was sown from May 10 to May 20 each year, with a row spacing of 65 cm and a plant spacing of 25 cm. After sowing, 30 mm of sprinkler irrigation was applied to ensure seedling emergence. Other field management measures, such as pest and disease control, were consistent with local conventional management methods.

[0042] Seedling strip sowing is alternated every other year: when sowing in the next year, the position of the seedling strip is adjusted to the straw covering strip of the previous year, and the original seedling strip is converted to the new covering strip, with an alternation cycle of 2 years; wide and narrow rows are used in conjunction with planting, with a wide row of 75 cm (covering area) and a narrow row of 45 cm (seedling strip). In wide and narrow row planting, the narrow row seedling strip is directly sown with a no-till seeder to break the stubble and the sowing depth is 3-5 cm.

[0043] The straw decomposition rate was calculated using the net bag method. After the corn matured in 2024, three 5 m double rows (6 m 2 ) for yield measurement. Representative ears were selected for testing and then harvested to determine actual yield. Soil samples were collected using the "S"-shaped sampling method, thoroughly mixed, and then naturally air-dried for determination of total soil carbon and total nitrogen.

[0044] Soil available nitrogen determination method: 1 mol / L KCl solution was used for oscillation extraction at a soil-to-liquid ratio of 1:5 for 1 hour. The extract was then analyzed for ammonium and nitrate nitrogen content using a flow analyzer. Experimental Results: The results are shown in Table 1. Compared with no inoculant application, a commercially available composite inoculant, a 2:1 ratio of psychrophile:anaerobic bacteria, or a single cellulose-degrading bacteria application, the 1:2:1 composite inoculant proposed in this invention significantly increased straw decomposition by 13.5% to 63.9%, soil available nitrogen content by 17.8% to 91.4%, and corn yield by 8.9% to 35.6%.

[0045] Table 2 Field effects of different microbial agents

[0046]

[0047] Example 2: Black soil improvement method by furrow application of manure and microbial agent combined with returning straw to the fields

[0048] The Qiqihar field trial was conducted in Meilisi, Qiqihar City, Heilongjiang Province (47°38' N, 123°68' E). The climate is temperate continental monsoon, with an average annual temperature of 4.7°C, a frost-free period of 150 days, and an average annual precipitation of 434.5 mm. Annual precipitation fluctuates significantly, with most precipitation occurring in August and September. The test soil was chernozem soil, with soil properties at the 0-20 cm depth of the soil containing 21.9 g·kg organic matter. -1 , alkaline nitrogen 99.8 mg·kg -1 , available phosphorus 13.9 mg·kg -1 , fast-acting potassium 155.5 mg·kg -1 , pH8.4.

[0049] The field trial began in 2021, with a comparison of broadcasting of manure and a 1:1.5:1 compound microbial agent and a shallow application of manure and a 1:1.5:1 compound microbial agent in furrows, followed by straw mulching and returning to the field as an experimental case. The trial used a field comparison method without replication, with each treatment area of ​​480 m 2 (60 m × 8 m). Each treatment included straw return (crushed to 5-8 cm and fully covered in 40-50 cm strips on both sides of the fertilizer strip, leaving 20-30 cm of the seedling strip exposed). A combined microbial agent was applied at a rate of 100 kg / mu and 1.5 t / mu of manure, applied in shallow furrows along the planting rows into the 0-15 cm soil layer. Corn was sown between May 10th and 20th each year, with a row spacing of 65 cm and a plant spacing of 25 cm. After sowing, 30 mm of spray irrigation was applied to ensure seedling emergence. Other field management measures, including pest and disease control, were consistent with local practices.

[0050] Seedling strip sowing is alternated every other year: when sowing in the next year, the position of the seedling strip is adjusted to the straw covering strip of the previous year, and the original seedling strip is converted to the new covering strip, with an alternation cycle of 2 years; wide and narrow rows are used in conjunction with planting, with a wide row of 75 cm (covering area) and a narrow row of 45 cm (seedling strip). In wide and narrow row planting, the narrow row seedling strip is directly sown with a no-till seeder to break the stubble and the sowing depth is 3-5 cm.

[0051] When the corn matures in 2024, select three 5 m double rows (6.5 m 2Yield was measured using the 2-step method, and representative ears were selected for seed testing. Three consecutive corn plants were selected from each treatment to measure aboveground biomass and underground root characteristics. Soil samples were collected using the "S" sampling method and air-dried before being analyzed for total carbon, total nitrogen, ammonia nitrogen, and nitrate nitrogen.

[0052] The determination method is as follows:

[0053] (1) Yield measurement method: Five plots with double rows of 5 meters were randomly selected for yield measurement. The corn was naturally air-dried and then threshed to determine the crop yield.

[0054] (2) Method for measuring aboveground biomass: Six corn plants were collected from each plot. Fresh aboveground samples were dried at 65°C to a constant mass, and the aboveground biomass was recorded.

[0055] (3) Nitrogen absorption determination method: Grind the plant sample obtained in (2) above until it passes through a 0.15 mm sieve, and determine the total nitrogen content of the plant based on the Kjeldahl method (Bremner and Mulvaney, 1982).

[0056] (4) Root length, root surface area, and root volume measurement methods: Three corn plants were randomly selected from each plot to measure root traits. Root samples were collected in nylon bags, rinsed with clean water, and carefully extracted from the soil. Root biomass was determined by scanning with an Epson Perfection V750 Pro scanner and then drying at 80°C to constant weight. Root sample images were analyzed using WinRHIZO software to estimate root length (RL, cm). -3 ), root surface area (RSA, cm 2 cm -3 ) and root volume (RV, cm 3 cm -3 ).

[0057] (5) Determination of soil organic carbon, total nitrogen, ammonia nitrogen and nitrate nitrogen: Soil organic carbon (SOC) content was determined by potassium dichromate volumetric method. Total nitrogen (TN) was determined by Kjeldahl digestion method. Ammonium nitrogen (NH4 + -N) and nitrate nitrogen (NO3 - -N) by 1 mol L -1 KCl was extracted at 25 °C and determined on a continuous flow analyzer (Seal Analytical, Germany, Autoanalyzer 3).

[0058] Experimental results:

[0059] The results are as follows Figure 2 and Figure 3 shown.

[0060] Depend on Figure 2 It can be seen that compared with the control example (broadcasting of manure and 1:1.5:1 compound microbial agent), the embodiment of the present invention (shallow application of manure and microbial agent in furrows and returning straw to the fields as a cover) increased corn yield by 32.0%, root volume by 44.2%, aboveground biomass by 44.3% and nitrogen absorption by 174.9%.

[0061] Depend on Figure 3 It can be seen that compared with the control example (broadcasting of manure and 1:1.5:1 compound microbial agent), the embodiment of the present invention (shallow application of manure and microbial agent in furrows and returning straw to the fields by mulching) increased the organic carbon in the surface soil by 9.2%, the total nitrogen by 18.7%, the inorganic nitrogen by 14.1%, and the average weight diameter of water-stable aggregates by 8.9%.

[0062] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may occur depending on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for improving black soil, comprising the following steps: Straw return to the field: After the previous crop is harvested, the straw of the previous crop is crushed and covered between the rows on both sides of the fertilizer strip in a strip width of 60-75 cm, leaving a 40-45 cm bare area in the seedling strip; Preparation of composite bacterial agent: psychrophilic bacteria, cellulolytic bacteria, and anaerobic bacteria are inoculated into LB culture medium to form bacterial liquid, the bacterial liquid is diluted 20-100 times, mixed according to the volume ratio of (1-2): (1-2): (1-2), and auxiliary materials are added to prepare composite bacterial agent; the psychrophilic bacteria, cellulolytic bacteria, and anaerobic bacteria are inoculated into LB culture medium to form bacterial liquid by inoculating psychrophilic bacteria, cellulolytic bacteria, and anaerobic bacteria into LB liquid culture medium at an inoculum amount of 1-5% by volume, wherein, The cellulolytic bacteria and the anaerobic bacteria are cultured at 15-20°C and 150-180 rpm for 1-3 days to form a cellulolytic bacteria solution and an anaerobic bacteria solution, respectively; the psychrophilic bacteria are cultured at a low temperature of 0-10°C and 150-180 rpm for 1-3 days to form a psychrophilic bacteria solution; the auxiliary materials include: 1-5 mg / ml trehalose as a protective agent, 0.5-3 mg / ml yeast extract powder as a nitrogen source, and 0.01-0.1 mg / ml vitamin premix; the vitamin premix contains thiamine, pyridoxine, and riboflavin; The compound bacterial agent is applied into the 0-15 cm soil layer by digging shallow furrows along the planting rows, with a dosage of 100-150 kg / mu; Seedling strip sowing is alternated every other year: when sowing in the next year, the position of the seedling strip is adjusted to the straw covering strip of the previous year, and the original seedling strip is converted to the new covering strip, with an alternation cycle of 2 years; wide and narrow rows are used in conjunction, with wide rows of 60~75 cm as the covering area and narrow rows of 40~45 cm as the seedling strip; in wide and narrow row planting, the narrow row seedling strip is directly sown through the stubble, with a sowing depth of 3-5 cm.

2. The black soil improvement method according to claim 1, characterized in that: The method further comprises the step of applying the composite bacterial agent in combination with manure; the mass ratio of the manure to the composite bacterial agent is 1-1.5:15-17.

3. The black soil improvement method according to claim 2, characterized in that: The manure and compound bacterial agent are shallowly applied into the 0-15 cm soil layer by digging trenches.

4. The black soil improvement method according to claim 1, wherein: The auxiliary material comprises the following components: 3.0 mg / ml trehalose as a protective agent, 1.5 mg / ml yeast extract powder as a nitrogen source, and 0.035 mg / ml vitamin premix; the vitamin premix contains 0.02 mg / ml thiamine, 0.01 mg / ml pyridoxine, and 0.005 mg / ml riboflavin.

5. The black soil improvement method according to claim 1 or 2, characterized in that: The bacterial solutions of the psychrophilic bacteria, the cellulolytic bacteria and the anaerobic bacteria are mixed in a volume ratio of 1:1.5:1 to 1:2:

1.

6. The method for improving black soil according to claim 5, characterized in that: The bacterial solutions of the psychrophilic bacteria, the cellulolytic bacteria and the anaerobic bacteria are mixed in a volume ratio of 1:2:

1.

7. The black soil improvement method according to claim 1 or 2, characterized in that: After the bacterial solution is diluted 20-100 times, the bacterial content in the bacterial solution is greater than 10 9 CFU / g.

8. The black soil improvement method according to claim 1, characterized in that: The mixed solution of the composite bacterial agent and the auxiliary materials is pre-frozen at -80°C for 2-4 hours and then transferred to a freeze dryer for freeze-drying or directly packaged in liquid form.

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