Complex microbial inoculant, biological stimulant, preparation method and application

Abstract

The invention discloses a complex microbial inoculant, a biological stimulant, a preparation method and application. The composite bacterial agent disclosed by the invention comprises Pristia aryabhattai P28 (the preservation number is CGMCC (China General Microbiological Culture Collection Center) 1.65035), bacillus subtilis S1 (the preservation number is CGMCC 1.65034) and bacillus velezensis C1 (the preservation number is CGMCC 1.65033), and the volume ratio of the P28 to the S1 to the C1 is 3 to 1 to 2. The biological stimulant is prepared from kitchen waste aerobic hydrolysate which is obtained by fermenting organic waste kitchen waste serving as a raw material with a complex microbial inoculant with the addition amount of 5% by volume. After the biological stimulant is applied to soil, the total amount of soil organisms (bacteria, fungi and protozoa) can be effectively increased, the soil aggregate stability is improved, and the soil structure is rapidly improved; the content of total organic carbon, granular organic carbon and soluble organic carbon in soil and the activity of soil enzymes (catalase, sucrase, urease and acid phosphatase) are obviously improved in a short time. The method disclosed by the invention has important significance on resource utilization of organic wastes and agricultural sustainable development.

Description

Technical Field

[0001] The present invention belongs to the technical field of crop planting. Specifically, it relates to a composite bacterium agent, a biological stimulant, and their preparation methods and applications. Background Art

[0002] Sand grains, silt grains, clay particles and organic matter in the soil are cemented and aggregated with each other to form aggregates of different sizes. They are further organized and arranged in three-dimensional space to form the macroscopic soil structure. Soil structure is a key factor for the soil to maintain basic ecosystem functions and quality. A good soil structure depends on the stability and particle size distribution of soil aggregates. Promoting the formation of aggregates and enhancing the stability of aggregates are of great significance for improving soil quality. Therefore, soil structure improvers can be artificially added to improve soil quality. Organic materials such as organic fertilizers and green manures as natural improvers can significantly improve soil aggregates, but usually have a long cycle and the stability of the formed aggregates is poor. Moreover, the improvement effects of other types of improvers (such as polyacrylamide, etc.) are very limited, with only a short-term promoting and stabilizing effect on aggregation and are prone to cause soil compaction. Therefore, it is necessary to develop new improvers that can quickly promote soil particle aggregation and have strong stability to improve soil structure and soil fertility.

[0003] Soil microorganisms and animals, known as "ecosystem engineers", play a key role in the formation and stabilization of soil aggregates. There is great development and application potential in promoting the formation and stabilization of soil aggregates by adding appropriate nutrients to improve and enhance the metabolic activity of native organisms. Selecting suitable biological stimulants is the focus of research and development. As kitchen waste, an urban organic waste, the various reducing sugars and volatile fatty acids produced by its aerobic hydrolysis can be used as carbon sources for soil organisms to quickly utilize, and it has a short fermentation cycle and high yield. Therefore, preparing soil biological stimulants by aerobic hydrolysis of kitchen waste is a good way for its resource utilization.

[0004] The present invention uses the aerobic hydrolysis solution of kitchen waste as a soil biological stimulant, which can quickly improve soil structure, increase the stability of aggregates, and enhance soil organic carbon content and soil enzyme activity. The preparation and application methods of the present invention are simple and low-cost, which will provide theoretical and technical guidance for the resource treatment of organic waste and agricultural management measures for promoting soil aggregation and fertilization. Summary of the Invention

[0005] In view of this, one of the objectives of the present invention is to provide a composite bacterial agent for efficiently degrading kitchen waste, which includes strains Priestia aryabhattai P28 (deposit number: CGMCC 1.65035), Bacillus subtilis S1 (deposit number: CGMCC 1.65034), and Bacillus velezensis C1 (deposit number: CGMCC 1.65033).

[0006] Preferably, the volume ratio of strains P28, S1, and C1 is 3:1:2. The specific preparation method is as follows: Inoculate P28, S1, and C1 into Luria-Bertani medium respectively and culture for 12 hours; centrifuge the culture solution at 8000 revolutions per minute for 10 minutes, collect the bacterial cells, wash them with sterile water and then centrifuge once again, remove the supernatant, and add phosphate buffer to make a bacterial suspension with an OD 600 of 0.7; prepare the composite bacterial agent by mixing the bacterial suspensions according to the volume ratio of P28:S1:C1 = 3:1:2.

[0007] Another objective of the present invention is to provide the application of the above composite bacterial agent in degrading kitchen waste.

[0008] A third objective of the present invention is to provide a biostimulant, which is the hydrolysate obtained by filtering the kitchen waste fermented by the above composite bacterial agent. Before adding the composite bacterial agent to ferment the kitchen waste, it generally needs to be pretreated to remove excess oil and salt. The pretreatment includes rinsing the kitchen waste with boiling water, then filtering, and finally removing the difficult-to-degrade plastic bags, bones, disposable tableware, etc. from the kitchen waste. The main components and contents of the pretreated kitchen waste are generally: water 70% - 90%, carbohydrates 5% - 25%, protein 1% - 8%, fat 0.5% - 5% (weight percentage).

[0009] Preferably, the composite bacterial agent is inoculated at 5% of the volume of the kitchen waste, and then fermented under the conditions of 35°C, 180 revolutions per minute, and an oxygen concentration of 10% for 3 days.

[0010] A fourth objective of the present invention is to provide a preparation method of a biostimulant, which includes the following steps: using kitchen waste as the raw material, and filtering after fermentation with the composite bacterial agent described in claim 1 with a volume addition amount of 5%.

[0011] Preferably, the fermentation conditions are: 35°C, 180 revolutions per minute, an oxygen concentration of 10%, and 3 days.

[0012] A fourth objective of the present invention is to provide the application of the above biostimulant in improving soil.

[0013] Preferably, the soil improvement includes enhancing soil biomass and / or promoting soil aggregate formation and / or increasing soil organic carbon content and / or enhancing soil enzyme activity.

[0014] Preferably, the soil organisms include bacteria and / or fungi and / or protozoa; the particle size of the soil aggregates is greater than 2 mm; the soil organic carbon includes total organic carbon and / or particulate organic carbon and / or soluble organic carbon; the soil enzymes include catalase and / or sucrase and / or urease and / or phosphatase.

[0015] Preferably, the biostimulant is evenly watered on the soil surface at a dosage of 225 kg / acre in dry weight or 1.32 t / acre in fresh weight (with a water content of 17%) 2 - 3 days before sowing or transplanting plants.

[0016] Preferably, the biostimulant is used in combination with the base fertilizer.

[0017] Preferably, the use of the biostimulant in combination with the base fertilizer is as follows: the base fertilizer is applied to the soil 2 - 3 days before sowing or transplanting plants, and the biostimulant is applied 2 - 3 days before applying the base fertilizer. It is better for plant growth to stabilize for 2 - 3 days after each fertilization.

[0018] The composite bacterial agent of the present invention includes Priestia aryabhattai P28 (deposit number: CGMCC 1.65035), Bacillus subtilis S1 (deposit number: CGMCC 1.65034), and Bacillus velezensis C1 (deposit number: CGMCC 1.65033), and the volume ratio of P28:S1:C1 is 3:1:2. This composite bacterial agent has a significant degradation effect on kitchen waste. After the biostimulant obtained by degradation is applied, it can effectively increase the total amount of soil organisms (bacteria, fungi, and protozoa), significantly increase the stability of soil aggregates, rapidly improve the soil structure, and significantly increase the content of total organic carbon, particulate organic carbon, and soluble organic carbon in the soil as well as the activity of soil enzymes (catalase, sucrase, urease, and acid phosphatase) in the short term. The preparation process of the biostimulant of the present invention is simple, the cost is low, the raw materials are easily available, and it makes full use of urban organic waste; it can also be applied together with the base fertilizer, and since it has been degraded by soil organisms, it will not cause secondary pollution and has broad application prospects. Description of the Drawings

[0019] Figure 1 Shows the effect of applying the biostimulant on the total amount of phospholipid fatty acids in the soil;

[0020] Figure 2 Shows the effect of applying the biostimulant on the total amount of phospholipid fatty acids of soil bacteria;

[0021] Figure 3 Effect of applying biostimulants on the total phospholipid fatty acids of soil fungi;

[0022] Figure 4 Effect of applying biostimulants on the total phospholipid fatty acids of soil protozoa. Detailed implementation manners

[0023] The present invention will be described in detail below in conjunction with embodiments. These embodiments are only illustrative and are not limited to the application scope of the present invention. The present invention is not limited to the following embodiments or implementation manners. Any modifications and deformations made without departing from the spirit of the present invention shall be included within the scope of the present invention. Unless otherwise specified, the experimental materials or reagents used in the following embodiments are all commercially available.

[0024] Example 1. Optimization test of composite kitchen waste degradation bacterial agent combination

[0025] 1.1 Method

[0026] In the early stage, the research group of the present inventor isolated and screened many strains with the function of degrading kitchen waste from kitchen waste. To optimize the kitchen waste degradation rate of the bacterial agent, preliminary combination research was carried out on these strains. Finally, three strains were selected for further ratio research. Through 16S rRNA sequencing and sequence alignment, it was determined that the three strains were Priestia aryabhattai (strain number: P28, preservation number: CGMCC 1.65035), Bacillus subtilis (strain number: S1, preservation number: CGMCC1.65034), and Bacillus velezensis (strain number: C1, preservation number: CGMCC 1.65033). The three strains were preserved in the General Microbiology Center of the China Microbial Strain Preservation Management Committee, and the preservation address was No. 1, Beichen West Road, Chaoyang District, Beijing. The specific research methods are as follows:

[0027] Preparation of simulated kitchen waste: A generally used formula was adopted to simulate the composition of kitchen waste substances, that is, the fresh weight ratio of meat, rice and vegetables was 1:2:1.

[0028] Detection method for the main component content of kitchen waste: After the kitchen waste was broken and mixed evenly, the total polysaccharide content was determined by the anthrone method, and the protein and fat contents were determined in accordance with the current national standards of the People's Republic of China (GB5009.5-2016 and GB5009.6-2016). The kitchen waste was dried to a constant weight, and the moisture content was calculated by dividing the difference between the fresh weight and the dry weight by the fresh weight.

[0029] Preparation method of microbial agent: Inoculate strains P28, S1 and C1 into Luria-Bertani medium and culture for 12 hours. Centrifuge the culture solution at 8000 revolutions per minute for 10 minutes, collect the thallus, wash it with sterile water and then centrifuge once again. After removing the supernatant, add phosphate buffer (pH = 7.4) to prepare a single-strain bacterial suspension (single-strain microbial agent) with an OD 600 of 0.7. The compound microbial agent is composed of P28, S1 and C1, that is, different combinations of compound microbial agents are prepared from the single-strain bacterial suspension according to different volume ratios of P28:S1:C1.

[0030] Optimization method for the ratio of P28:S1:C1: First, optimize the inoculation amount ratio of strain P28 (Combination A), that is, set the inoculation ratios of P28:S1:C1 as 1:1:1, 2:1:1, 3:1:1, 4:1:1. After selecting the optimal inoculation amount of strain P28, then optimize the inoculation amount of strain S1 (Combination B), and finally optimize the inoculation amount of strain C1 (Combination C), so as to obtain the optimal ratio of P28:S1:C1. The combinations and ratios of each compound microbial agent are shown in Table 1.

[0031] Calculation of fermentation and degradation rate: Inoculate each microbial agent at 5% (V / V) of the volume of the prepared simulated kitchen waste (the main component content is 122.5 g / kg of total sugar content, 20 g / kg of fat content, 57.5 g / kg of protein content, and 70% of water content). Each microbial agent is one treatment, with 3 replicates for each treatment. The strain ratios of each treatment are shown in Table 1, and no inoculation of microbial agent is used as the control; then carry out fermentation. The fermentation method is to use a mechanical stirring fermenter and culture under the conditions of 35 °C, 180 revolutions per minute, and forced ventilation for oxygen supply (the oxygen concentration is maintained at about 10%) for 3 days; then filter the hydrolyzed mixture of the fermented kitchen waste through a 40-mesh sieve, take the solid and dry it, which is the residual amount of kitchen waste solid. Calculate the degradation rate by dividing the difference between the residual amounts of kitchen waste solid in the control and the treatment by the residual amount of kitchen waste solid in the control.

[0032] 1.2 Results

[0033] As shown in Table 1 for the compound microbial agent formulation and degradation rate, the degradation rates of each compound microbial agent combination for simulated food waste are higher than those of single strains, and there are significant differences, indicating that the compound microbial agent can degrade food waste more efficiently. The degradation rate of simulated food waste increases with the increase in the inoculation ratio of P28 in the compound microbial agent. The optimal rates are 3:1:1 and 4:1:1, with degradation rates of 51.98% and 52.11% respectively, but the difference is not obvious. Considering the principle of cost optimization, the optimal ratio of the inoculation amount of P28 strain is determined to be 3:1:1. Similarly, the optimal inoculation amount ratios of S1 and C1 strains are determined in turn, and finally the optimized compound food waste degradation microbial agent combination ratio is P28:S1:C1 = 3:1:2, with a degradation rate of simulated food waste reaching 57.64%. The degradation rate has a significant difference compared with compound microbial agents with other formulations, being 3.27% higher than the combination with the second highest degradation rate (P28:S1:C1 = 3:1:3), and the effect is obvious.

[0034] Table 1 Influence of Strain Inoculation Ratio on Complete Liquefaction of Simulated Food Waste

[0035]

[0036] Note: Group A represents taking the P28 strain as the single variable, Group B represents taking the S1 strain as the single variable, and Group C represents taking the C1 strain as the single variable; the degradation rate is the average of 3 replicates.

[0037] Example 2: Verification Test on the Effect of the Optimal Compound Food Waste Degradation Microbial Agent Combination

[0038] 2.1 Method

[0039] To further verify the degradation effect of the optimal compound food waste degradation microbial agent combination in actual production, natural food waste is selected to replace simulated food waste. The natural food waste is taken from the cafeteria of Southwest University, and the sampling time is from 12:40 to 13:00 at noon. The collected food waste is first pretreated: first, the food waste is rinsed with boiling water, then filtered, and finally, hard-to-degrade plastic bags, bones, disposable tableware, etc. are removed. After pretreatment, the microbial agent is inoculated and fermented. The preparation, formulation, and inoculation amount of the microbial agent are the same as those in 1.1, and the fermentation and degradation rate calculation methods are also the same as those in 1.1. At the same time, the main component contents of the pretreated food waste are detected according to the method in 1.1, with a moisture content of 82.5%, a total sugar content of 71.8 g / kg, a fat content of 11.5 g / kg, and a protein content of 16.7 g / kg.

[0040] 2.2 Results

[0041] As shown in Table 2, the degradation effect and trend of the inoculation ratio of each strain on natural kitchen waste were consistent with those of simulated kitchen waste. The specific results showed that compared with single strains, the compound bacterium agent could degrade natural kitchen waste more efficiently; at the same time, it further proved that P28:S1:C1 = 3:1:2 was the optimal combination of compound kitchen waste degradation bacterium agents, and its degradation rate of natural kitchen waste could reach 65.89%, which was 4.83% higher than that of the second-highest degradation rate combination (P28:S1:C1 = 3:1:3), and the effect was obvious.

[0042] Table 2 Effect of strain inoculation ratio on the complete liquefaction of natural kitchen waste

[0043]

[0044] Note: Combination A represents taking strain P28 as a single variable, combination B represents taking strain S1 as a single variable, and combination C represents taking strain C1 as a single variable; the degradation rate is the average value of 3 replicates.

[0045] Example 3. Soil culture experiment

[0046] 3.1 Method

[0047] Test soil and treatment: The 0-20 cm soil layer where corn was planted in the agricultural comprehensive demonstration base in Daguan Town, Nanchuan District, Chongqing was taken. The soil type was gray-brown purple mud, and the soil pH value was 4.41. The collected soil was air-dried naturally and mixed evenly, and then passed through a 2 mm sieve to remove plant residues and stones and then put into pots. Each culture pot was filled with 4.5 kg of dry soil, and incubated for two weeks at 60% of the maximum water holding capacity of the soil to restore soil microorganisms.

[0048] Preparation of biostimulant: The hydrolysate obtained by fermenting kitchen waste with the compound bacterium agent of P28:S1:C1 = 3:1:2 and then filtering out the residues was the biostimulant. The specific steps included: taking the kitchen waste from the cafeteria of Southwest University, the acquisition time was 12:40 - 13:00 at noon. After pretreatment of boiling water rinsing, filtering, and removing difficult-to-degrade substances, it was inoculated with the compound bacterium agent at 5% (V / V) of the volume of the kitchen waste after pretreatment and then fermented. The fermentation method was to use a mechanical stirring fermenter and ferment for 3 days under the conditions of 35 °C, 180 revolutions per minute, and forced ventilation for oxygen supply (the oxygen concentration was maintained at about 10%). The hydrolysate obtained by filtering the residual solids from the fermented kitchen waste hydrolysis mixture was the biostimulant for subsequent experiments. The preparation of the compound bacterium agent of P28:S1:C1 = 3:1:2 was the same as the method in 1.1.

[0049] One blank group (without exogenous substances applied), one control group (glucose solution was applied, and the glucose addition amount was the dry matter amount of glucose at 0.18% of the soil weight), and one treatment group (the above-mentioned biostimulant was applied, and the application amount was the dry matter amount of biostimulant at 0.15% of the soil weight, that is, 225 kg / mu of dry weight) were set up. The total carbon content of the glucose application was the same as that of the biostimulant, and the application volume was also the same. There were 3 replicates for each treatment. The cultivation location was the greenhouse of the College of Resources and Environment, Southwest University, and the soil was maintained at 60% of the maximum water holding capacity. Soil samples were collected at 20 days, 40 days, and 60 days of cultivation. All soil samples were divided into two parts: (1) air-dried naturally to measure the particle size distribution of soil water-stable aggregates, soil carbon components, and soil enzyme activities; (2) stored at -80 °C to measure the content of soil total phospholipid fatty acids (PLFA).

[0050] Method for determining soil water-stable aggregates: First, take 400 g of the mixed soil sample and place it on the top of a set of sieves (with pore sizes of 2, 0.25, and 0.053 mm in sequence). Use a vibrating sieve shaker for vibrating sieving with an amplitude of 2 mm and a sieving time of 10 minutes to measure the soil mass after sieving through each pore size. According to the mass ratio of each particle size of the soil after dry sieving, weigh 50 g of the mixed soil sample, place it on the top of a set of sieves (with pore sizes of 2, 0.25, and 0.053 mm in sequence), put it in the supporting bucket of a constant-temperature soil aggregate analyzer, slowly add deionized water along the edge to the scale, ensure that the upper edge of the top sieve is lower than the water surface, start oscillation after standing for 10 minutes, and oscillate at a frequency of 30 times / minute for 10 minutes. Collect the aggregates on each sieve layer and transfer them to aluminum boxes respectively, dry and weigh. Using the data of water-stable aggregates of each particle size, calculate the mean weight diameter and the mass fraction of aggregates larger than 0.25 mm to characterize the stability of soil aggregates.

[0051] Soil total organic carbon was determined by the potassium dichromate oxidation-external heating method; particulate organic carbon was determined by dispersing with sodium hexametaphosphate and the potassium dichromate oxidation-external heating method; soluble organic carbon was determined by dissolving with 2 mol / L potassium chloride and the potassium dichromate oxidation-external heating method.

[0052] Soil catalase activity was determined by volumetric method with potassium permanganate titration; soil sucrase activity was determined by 3,5-dinitrosalicylic acid colorimetric method; soil urease activity was determined by phenol sodium-sodium hypochlorite colorimetric method; soil acid phosphatase activity was determined by phenyl phosphate disodium colorimetric method.

[0053] The total amount of soil phospholipid fatty acids (PLFAs) was used to reflect the total amount of soil organisms (bacteria, fungi, and protozoa). Soil PLFAs were determined using the modified Bligh-Dyer method. A fresh soil sample equivalent to 8 g of dry soil was weighed, and lipids were extracted with a mixed extraction solution (chloroform:methanol:buffer = 2:1:0.8). PLFAs were separated by column chromatography and then analyzed for their composition by gas chromatography (Aligent 6850 with an FID detector) after methylation. PLFAs 18:1ω9t, 18:1ω9c, 18:2ω6t, 18:2ω6c, 18:3ω6c, 18:3ω3c, 21:0, and C23:0 were used as fungal indicators; PLFAs 12:0, br 16:0, 13:0, 14:0, 14:1ω9c, 15:0, i 7:0, 16:1ω9c, a 17:0, 17:0, cyC 17:0, a 18:0, 17:1ω10c, 18:0, i 19:0, a 19:0, 18:1ω13t, cyC 19:0, 20:0, 20:1ω11c, 20:2ω11c, 22:0, 22:1ω13c, 20:5ω5c, and 22:6ω4c were used as bacterial indicators; and 20:3ω6c, 20:4ω6c, and 20:3ω11c were used as protozoan indicators.

[0054] 3.2 Results

[0055] 3.2.1 Effects of biostimulants on the composition of soil PLFAs

[0056] PLFA is a method for qualitatively and quantitatively analyzing the total amount and diversity of soil biological communities. Based on the species specificity of the PLFA composition and content of different microorganisms, their biomass and community structure are estimated. Figure 1 This shows the change in the total amount of soil PLFAs after the application of biostimulants. It can be seen that compared with the blank group and the control group, the treatment group can effectively increase the total amount of PLFAs within 60 days and reaches a peak at 40 days. Therefore, the application of biostimulants can effectively increase the total amount of soil organisms. As Figure 2 shown, the change trend of the total amount of bacterial PLFAs is consistent with that of the total amount of soil PLFAs, that is, the application of biostimulants can effectively increase the total amount of soil bacteria. Figure 3 This shows the change in the total amount of soil fungal PLFAs after the application of biostimulants. The treatment group can significantly increase the total amount of fungal PLFAs within 60 days. Therefore, the application of biostimulants can significantly and long-lastingly increase the total amount of soil fungi. As Figure 4 can be seen from the results, the treatment group significantly increased the total amount of soil protozoan PLFAs at 40 days and 60 days, indicating that the application of biostimulants can significantly and long-lastingly increase the total amount of soil protozoa.

[0057] 3.2.2 Effects of biostimulants on the stability of soil aggregates

[0058] As shown in Table 3, compared with the blank group and the control group, the treatment group significantly increased the proportion of aggregates with a particle size > 2 mm within 60 days, and the improvement effect was the greatest at 20 days (75.28% and 44.3%); at the same time, it significantly reduced the proportions of aggregates with particle sizes of 2 - 0.25 mm and 0.25 - 0.053 mm, indicating that the application of biostimulants promoted the transformation of small soil aggregates into large aggregates. The mean weight diameter and the mass fraction of aggregates with a particle size > 0.25 mm are important indicators to characterize the stability of soil aggregates. The larger their values, the higher the degree of aggregation of the average particle size and the stronger the stability. Within 60 days, the stability of the aggregates in the treatment group was higher than that in the blank group and the control group, and the improvement effect was the greatest at 20 days. Generally speaking, the application of biostimulants can improve the stability of soil aggregates and rapidly improve the soil structure.

[0059] Table 3 Effects of biostimulants on the stability of soil aggregates

[0060]

[0061] 3.2.3 Effects of biostimulants on the fractionation of soil organic carbon

[0062] As can be seen from Table 4, compared with the blank group and the control group, the treatment group could increase the contents of total soil organic carbon and particulate organic carbon at 20 days, indicating that the application of biostimulants could rapidly increase the total soil organic carbon and particulate organic carbon in the soil in the short term. The treatment group could effectively increase the content of soluble organic carbon within 60 days. Therefore, the application of biostimulants could long-term increase the content of soluble organic carbon in the soil.

[0063] Table 4 Effects of biostimulants on the fractionation of soil organic carbon

[0064]

[0065] 3.2.4 Effects of biostimulants on soil enzyme activity

[0066] Soil catalase is an important enzyme for soil microbial metabolism and plays an important role in the H2O2 scavenging system. As can be seen from Table 5, compared with the blank group and the control group, the treatment group can increase the soil catalase activity within 40 days, indicating that the application of biostimulants can effectively stimulate the soil biological metabolic activity in the short term. Soil sucrase can hydrolyze sucrose into corresponding monosaccharides for absorption by the organism. Its enzymatic action products are closely related to the content of organic matter, nitrogen, phosphorus, the number of microorganisms and the soil respiration intensity in the soil, and it is an important indicator for evaluating soil fertility. The treatment group can significantly increase the soil sucrase activity within 60 days, indicating that the application of biostimulants can greatly promote the soil carbon cycle intensity in the long term. Soil urease activity is positively correlated with the number of soil microorganisms, the content of organic matter, total nitrogen and available nitrogen content. Its activity reflects the nitrogen supply status of the soil and plays an important role in the soil nitrogen cycle. The treatment group can increase the soil urease activity within 40 days, so the application of biostimulants can effectively stimulate the soil nitrogen cycle intensity. Soil phosphatase is a class of enzymes that catalyze the mineralization of soil organic phosphorus. The level of its activity directly affects the decomposition and transformation of organic phosphorus in the soil and its biological availability, and it is an indicator for evaluating the direction and intensity of soil phosphorus biotransformation. The treatment group can significantly increase the soil acid phosphatase activity within 60 days, indicating that the application of biostimulants can effectively stimulate the soil phosphorus cycle intensity in the long term.

[0067] Table 5 Effects of biostimulant application on soil enzyme activities

[0068]

[0069] The experimental results in the above examples are all the averages of 3 treatments. In addition, the conventional techniques and the schemes not described in detail in the experiments are well known in the art, so they will not be elaborated here. The above examples and / or experimental examples have described the preferred embodiments of the present invention in detail. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A composite microbial agent for efficiently degrading kitchen waste, characterized in that, It includes strains Priestia aryabhattai P28 (deposit number: CGMCC 1.65035), Bacillus subtilis S1 (deposit number: CGMCC 1.65034), and Bacillus velezensis C1 (deposit number: CGMCC 1.65033).

2. The compound microbial agent according to claim 1, wherein The volume ratio of the strains P28, S1, and C1 is 3:1:

2.

3. The application of the composite microbial agent according to claim 1 in degrading kitchen waste.

4. A biostimulant, characterized in that, It is the hydrolysate obtained by filtering the kitchen waste fermented by the composite microbial agent according to claim 1.

5. The biostimulant according to claim 4, characterized in that, The composite microbial agent is inoculated at 5% of the volume of the kitchen waste, and then fermented for 3 days under the conditions of 35°C, 180 revolutions per minute, and an oxygen concentration of 10%.

6. A preparation method of a biostimulant, characterized in that, It includes the following steps: using kitchen waste as the raw material, and obtaining it by filtering after fermentation with the composite microbial agent according to claim 1 at an addition amount of 5% by volume.

7. The method according to claim 6, wherein The fermentation conditions are: 35°C, 180 revolutions per minute, an oxygen concentration of 10%, and 3 days.

8. The application of the biostimulant according to claim 4 or 5 in improving soil.

9. The application according to claim 8, wherein, The improved soil includes enhancing soil biomass and / or promoting the formation of soil aggregates and / or enhancing soil organic carbon content and / or enhancing soil enzyme activity.

10. The application according to claim 9, characterized in that, The soil organisms include bacteria and / or fungi and / or protozoa; the particle size of the soil aggregates is greater than 2 mm; the soil organic carbon includes total organic carbon and / or particulate organic carbon and / or soluble organic carbon; the soil enzymes include catalase and / or sucrase and / or urease and / or phosphatase.

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