Composite organic fertilizer and preparation method thereof
By using oxidized modified straw biochar and ammonified superphosphate in the preparation of organic fertilizer, the problem of incomplete decomposition caused by shortening the composting time was solved, and efficient composting and low-toxicity organic fertilizer production were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANYANG ZHAOFU AGRI TECH DEV CO LTD
- Filing Date
- 2026-04-03
- Publication Date
- 2026-06-09
AI Technical Summary
In existing technologies, shortening composting time to improve the efficiency of organic fertilizer preparation can easily lead to incomplete composting, thereby increasing the phytotoxicity of organic fertilizer.
By combining oxidized straw biochar and ammonified superphosphate, the composting rate is improved through microbial activation and pore structure management.
While shortening the composting time, it significantly improves the compost maturity, reduces the phytotoxicity of organic fertilizer, and ensures the safety and efficacy of compost products.
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Figure CN122167223A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of waste-to-fertilizer technology, and in particular relates to a compound organic fertilizer and its preparation method. Background Technology
[0002] Organic fertilizer is an important source of nutrients in my country's agricultural production. For a long time, traditional Chinese agriculture has relied on the application of organic fertilizer to improve soil fertility and increase crop yields. Organic fertilizer contains abundant organic matter and various nutrients, boasting advantages such as large quantity, wide availability, comprehensive nutrient content, and low pollution during application. Organic fertilizer not only contains all the nutrients needed by plants, such as N, P, K, Ca, Mg, S, and trace elements, but also a large amount of organic matter, thus making it a complete fertilizer. The preparation of organic fertilizer mainly relies on composting, fermentation, and fermentation processes to transform organic waste into nutrient-rich humus. The composting process is essentially a biochemical reaction, in which microorganisms play a central driving role.
[0003] Maturity refers to the degree to which compost has decomposed, that is, the extent to which the organic matter in the compost has reached a stable state after undergoing mineralization and humification processes. As a key indicator for evaluating / measuring the quality of compost products, maturity has long been established. Its basic meaning is: ① Through the action of microorganisms, the compost product should achieve stabilization and harmlessness, meaning it should not have adverse effects on the environment; ② The use of compost products should not affect crop growth or soil tillage capacity. Internationally, maturity is widely regarded as a core conceptual parameter for measuring the progress of the composting reaction. Compost maturity directly affects the application effect of compost products. Once uncomposted compost is applied to the soil, it will trigger excessive microbial activity, causing oxygen shortage, creating an anaerobic environment, and hindering root development. Moreover, in this environment, uncomposted compost will also generate a large number of intermediate metabolites, such as organic acids, and harmful substances such as NH3 and H2S produced in a reducing state. These components can seriously damage plant roots and affect normal crop growth. In addition, the pungent odor emitted by uncomposted compost also greatly limits its practical application. To effectively avoid the above problems, testing and controlling the compost maturity has become an important part of composting process implementation and product quality control.
[0004] In existing technologies, the germination index (GI) is a biological indicator measuring seed vigor, and it can also be used to evaluate the maturity of compost. Generally, a germination index exceeding 50% indicates that the compost is essentially non-toxic to plants and has reached basic maturity; a germination index of 80%-85% or higher indicates that the compost has eliminated phytotoxicity and can be considered fully mature. Maturity typically increases with composting time; sufficient composting time is necessary for complete maturity. Shortening composting time to increase production efficiency (organic fertilizer production efficiency) may directly lead to incomplete composting, resulting in increased phytotoxicity of the produced organic fertilizer. Summary of the Invention
[0005] To address the above problems, this invention provides a compound organic fertilizer and its preparation method, which improves the efficiency of organic fertilizer preparation by shortening the composting time, while further reducing the plant toxicity of the prepared organic fertilizer; that is, effectively improving the composting maturity rate.
[0006] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a compound organic fertilizer, comprising the following steps: S1. By weight, mix 27-30 parts of rice straw (cut into 20-40mm pieces), 9-10 parts of wheat bran, and 8-9 parts of animal manure to obtain the initial raw materials; S2. Add 0.85-0.9 parts of oxidized modified straw biochar and 0.5-0.55 parts of ammonified superphosphate to the initial raw material obtained in S1, mix them, and then add water to adjust the moisture content to 53±3% to obtain the base material. S3. Add *Phanerochaete chrysosporium* suspension and *Bacillus subtilis* activation solution to the substrate obtained in S2 and mix well to obtain fermentation material; the ratio of the amount of *Phanerochaete chrysosporium* suspension added to the substrate is 10-11 mL / kg; the ratio of the amount of *Bacillus subtilis* activation solution added to the substrate is 9-10 mL / kg. S4. The fermented material obtained in S3 is composted for more than 28 days to obtain the compound organic fertilizer.
[0007] Furthermore, the oxidized modified straw biochar is prepared by carbonizing rice straw at 500±10℃ for 2-2.3h, followed by oxidation treatment with 28-30wt% hydrogen peroxide aqueous solution for 1.8-2.2h.
[0008] Further, the preparation method of the ammonified superphosphate is as follows: superphosphate and urea are mixed at a mass ratio of 1:(0.1-0.15), water is added to a moisture content of 21-24%, and the mixture is stirred at 80-85℃ for 2-2.5 hours to allow the ammonia gas generated by the hydrolysis of urea to react with the free phosphoric acid contained in the superphosphate. After drying, it is pulverized to obtain the product.
[0009] Furthermore, the preparation method of the *Phanerochaete chrysosporium* suspension is as follows: *Phanerochaete chrysosporium* is inoculated onto PDA medium and cultured for 3 days; spores are scraped off to prepare a bacterial suspension, and its concentration is adjusted to 2-3 × 10⁻⁶. 8 The result is obtained as [number] cells / mL.
[0010] Furthermore, the preparation method of the Bacillus subtilis activation solution is as follows: by weight, 1 part of Bacillus subtilis, 1 part of brown sugar, and 23-25 parts of warm water at 32-35℃ are mixed and allowed to stand for activation for 28-32 minutes to obtain the solution.
[0011] Furthermore, the viable count of the Bacillus subtilis is 4.7-5.4 × 10⁻⁶. 8 / g.
[0012] Furthermore, in S1, the animal excrement includes pig manure, chicken manure and sheep manure, and the mass ratio of the three is 1:(1-1.5):(1-1.5).
[0013] Furthermore, in S4, during the composting fermentation period, the compost pile is turned over 2-3 times per week for the first two weeks, and then 1-2 times per week thereafter.
[0014] Secondly, the present invention provides a compound organic fertilizer prepared by the above-described preparation method.
[0015] Compared with the prior art, the present invention has the following beneficial effects: In the preparation of compound organic fertilizer in this invention, the addition of oxidized modified straw biochar has two positive effects: First, the porous structure of oxidized modified straw biochar directly increases the porosity of the compost pile, improves the ventilation conditions of the pile in the long term, provides sufficient oxygen for aerobic microorganisms, promotes / accelerates the aerobic composting process, and increases the composting rate to reduce plant toxicity more quickly. Second, it also has negative effects: The well-developed porous structure of oxidized modified straw biochar is prone to adsorbing moisture and organic matter and becoming blocked in the early stage of composting, which obstructs air circulation in local areas, forms an anaerobic microenvironment, promotes the generation of organic acids, leads to increased plant toxicity, and inhibits seed germination (reduces the germination index).
[0016] Simultaneously, the addition of ammonified superphosphate (ammoniation eliminates the acidity of superphosphate to avoid inhibiting microbial activity due to its low pH during addition) provides water-soluble phosphorus that can directly meet the needs of microorganisms (Bacillus subtilis, Phanerochaete chrysosporium), rapidly activating microbial activity, accelerating the degradation of cellulose and lignin, shortening the organic matter decomposition cycle, and increasing the composting rate. Furthermore, the activated microorganisms can decompose the organic matter that initially clogs the pores of the oxidized straw biochar, promoting / facilitating the maintenance of unobstructed pores in the oxidized straw biochar to fully exert its role in improving ventilation, effectively weakening or even offsetting the negative impacts caused by the oxidized straw biochar; thus synergistically improving the composting rate. Attached Figure Description
[0017] Figure 1 This is a comparison chart of seed germination index-composting time curves in the preparation of compound organic fertilizer in Example 1 and Comparative Examples 1-3 of the present invention. Detailed Implementation
[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0019] Unless otherwise specified, the raw materials used in the embodiments / comparative examples of this invention are all commercially available.
[0020] The oxidized modified straw biochar involved in the embodiments / comparative examples of the present invention was prepared by carbonizing rice straw at 500°C for 2.2 hours and then oxidizing it with 29wt% hydrogen peroxide solution for 2 hours.
[0021] The specific preparation steps are as follows: Step 1: Wash and dry the rice straw (60℃, 24h), then crush it to a particle size of about 1mm to obtain straw powder.
[0022] Step 2: Place the straw powder in a tube furnace, heat it to 500℃ at 10℃ / min under nitrogen protection, hold it at that temperature for 2 hours, and then let it cool naturally to room temperature to obtain raw biochar.
[0023] The carbonization temperature of 500℃ balances the development of biochar pores and structural stability, avoiding pore collapse due to excessively high temperatures and insufficient pores due to excessively low temperatures.
[0024] Step 3: Add the original biochar to a 29wt% H2O2 solution at a solid-liquid ratio of 1g:8mL, stir at 80℃ for 2h, cool and wash repeatedly with deionized water until neutral, and dry at 105℃ for 24h to obtain oxidized modified straw biochar.
[0025] The optimal concentration of 29wt% H2O2 solution is to avoid both insufficient concentration leading to weak modification and excessive concentration damaging the biochar framework.
[0026] The preparation method of aminated superphosphate involved in the embodiments / comparative examples of the present invention is as follows: superphosphate and urea are mixed at a mass ratio of 1:0.12, water is added to a moisture content of 23%, and the mixture is stirred at 82°C for 2.3 hours (so that the ammonia gas generated by the hydrolysis of urea reacts with the free phosphoric acid contained in superphosphate). After drying, the mixture is pulverized to obtain aminated superphosphate.
[0027] The preparation method of *Phanerochaete chrysosporium* suspension involved in the embodiments / comparative examples of this invention is as follows: *Phanerochaete chrysosporium* is inoculated onto PDA medium and cultured for 3 days. Spores are scraped off to prepare a bacterial suspension, and its concentration is adjusted to obtain the *Phanerochaete chrysosporium* suspension with a concentration of 2.7 × 10⁻⁶. 8 Cells / mL. *Phanerochaete chrysosporium* (Walner Biotechnology / N-53097) was purchased from Wuhan Walner Biotechnology Co., Ltd.
[0028] The preparation method of the Bacillus subtilis activation solution involved in the embodiments / comparative examples of this invention is as follows: Based on weight, 1 part of Bacillus subtilis (viable count 5.1 × 10⁻⁶) was used. 8 Mix 1 part brown sugar and 24.5 parts warm water at 34℃ with 1 part brown sugar and let stand for 30 minutes to activate, thus obtaining the Bacillus subtilis activation solution. Bacillus subtilis (ATCC / WN-14384) was purchased from Wuhan Huanna Biotechnology Co., Ltd.
[0029] Other specific details of the embodiments / comparative examples of the present invention are as follows.
[0030] Example 1: This example specifically provides a method for preparing compound organic fertilizer, including the following steps: S1. By weight, mix 28 parts of rice straw (cut into 20-40mm pieces), 9.5 parts of wheat bran, and 8.5 parts of animal manure to obtain the initial raw materials.
[0031] The animal excrement is a mixture of pig manure, chicken manure, and sheep manure in a mass ratio of 1:1.2:1.2.
[0032] S2. Add 0.87 parts of oxidized modified straw biochar and 0.53 parts of ammonified superphosphate to the initial raw material obtained in S1, mix them, and then add water to adjust the moisture content to 53.9% to obtain the base material.
[0033] S3. Add *Phanerochaete chrysosporium* suspension and *Bacillus subtilis* activation solution to the substrate obtained in S2 and mix well to obtain fermentation material; the ratio of the amount of *Phanerochaete chrysosporium* suspension added to the mass of the substrate is 10.5 mL / kg; the ratio of the amount of *Bacillus subtilis* activation solution added to the mass of the substrate is 9.5 mL / kg.
[0034] S4. The fermented material obtained in S3 is composted for 35 days. Composting itself is an existing technology in this field. During this period, the compost is turned over 3 times a week for the first two weeks and then 2 times a week thereafter, thus obtaining compound organic fertilizer.
[0035] Example 2: This example specifically provides a method for preparing compound organic fertilizer, including the following steps: S1. By weight, mix 27 parts of rice straw (cut into 20-40mm pieces), 9 parts of wheat bran, and 8 parts of animal manure to obtain the initial raw materials.
[0036] The animal excrement is a mixture of pig manure, chicken manure, and sheep manure in a mass ratio of 1:1.2:1.2.
[0037] S2. Add 0.85 parts of oxidized modified straw biochar and 0.5 parts of ammonified superphosphate to the initial raw material obtained in S1, mix them, and then add water to adjust the moisture content to 54.4% to obtain the base material.
[0038] S3. Add *Phanerochaete chrysosporium* suspension and *Bacillus subtilis* activation solution to the substrate obtained in S2 and mix well to obtain fermentation material; the ratio of the amount of *Phanerochaete chrysosporium* suspension added to the substrate is 10.5 mL / kg; the ratio of the amount of *Bacillus subtilis* activation solution added to the substrate is 9.5 mL / kg. S4. Compost the fermented material obtained in S3 for 35 days. During the composting process, turn the compost pile 3 times a week for the first two weeks and 2 times a week thereafter to obtain compound organic fertilizer.
[0039] Example 3: This example specifically provides a method for preparing compound organic fertilizer, including the following steps: S1. By weight, mix 30 parts of rice straw (cut into 20-40mm pieces), 10 parts of wheat bran, and 9 parts of animal manure to obtain the initial raw materials.
[0040] The animal excrement is a mixture of pig manure, chicken manure, and sheep manure in a mass ratio of 1:1.2:1.2.
[0041] S2. Add 0.9 parts of oxidized modified straw biochar and 0.55 parts of ammonified superphosphate to the initial raw material obtained in S1, mix them, and then add water to adjust the moisture content to 53.2% to obtain the base material.
[0042] S3. Add *Phanerochaete chrysosporium* suspension and *Bacillus subtilis* activation solution to the substrate obtained in S2 and mix well to obtain fermentation material; the ratio of the amount of *Phanerochaete chrysosporium* suspension added to the substrate is 10.5 mL / kg; the ratio of the amount of *Bacillus subtilis* activation solution added to the substrate is 9.5 mL / kg. S4. Compost the fermented material obtained in S3 for 35 days. During the composting process, turn the compost pile 3 times a week for the first two weeks and 2 times a week thereafter to obtain compound organic fertilizer.
[0043] Comparative Example 1: The difference between this comparative example and Example 1 is that no oxidized modified straw biochar and ammonified superphosphate are added in the preparation of the compound organic fertilizer.
[0044] Specifically, a method for preparing a compound organic fertilizer includes the following steps: S1. By weight, mix 28 parts of rice straw (cut into 20-40mm pieces), 9.5 parts of wheat bran, and 8.5 parts of animal manure to obtain the initial raw materials.
[0045] The animal excrement is a mixture of pig manure, chicken manure, and sheep manure in a mass ratio of 1:1.2:1.2.
[0046] S2. Add water to the initial raw material obtained in S1 to adjust the moisture content to 53.9% to obtain the base material.
[0047] S3. Add *Phanerochaete chrysosporium* suspension and *Bacillus subtilis* activation solution to the substrate obtained in S2 and mix well to obtain fermentation material; the ratio of the amount of *Phanerochaete chrysosporium* suspension added to the mass of the substrate is 10.5 mL / kg; the ratio of the amount of *Bacillus subtilis* activation solution added to the mass of the substrate is 9.5 mL / kg.
[0048] S4. Compost the fermented material obtained in S3 for 35 days. During the composting process, turn the compost pile 3 times a week for the first two weeks and 2 times a week thereafter to obtain compound organic fertilizer.
[0049] Comparative Example 2: The difference between this comparative example and Example 1 is that ammonified superphosphate is not added in the preparation of the compound organic fertilizer.
[0050] Specifically, a method for preparing a compound organic fertilizer includes the following steps: S1. By weight, mix 28 parts of rice straw (cut into 20-40mm pieces), 9.5 parts of wheat bran, and 8.5 parts of animal manure to obtain the initial raw materials.
[0051] S2. Add 0.87 parts of oxidized modified straw biochar to the initial raw material obtained in S1 and mix. Then add water to adjust the moisture content to obtain the base material.
[0052] S3. Add *Phanerochaete chrysosporium* suspension and *Bacillus subtilis* activation solution to the substrate obtained in S2 and mix well to obtain fermentation material; the ratio of the amount of *Phanerochaete chrysosporium* suspension added to the mass of the substrate is 10.5 mL / kg; the ratio of the amount of *Bacillus subtilis* activation solution added to the mass of the substrate is 9.5 mL / kg.
[0053] S4. Compost the fermented material obtained in S3 for 35 days. During the composting process, turn the compost pile 3 times a week for the first two weeks and 2 times a week thereafter to obtain compound organic fertilizer.
[0054] Comparative Example 3: The difference between this comparative example and Example 1 is that no oxidized modified straw biochar is added in the preparation of the compound organic fertilizer.
[0055] Specifically, a method for preparing a compound organic fertilizer includes the following steps: S1. By weight, mix 28 parts of rice straw (cut into 20-40mm pieces), 9.5 parts of wheat bran, and 8.5 parts of animal manure to obtain the initial raw materials.
[0056] S2. Add 0.53 parts of aminated superphosphate to the initial raw material obtained in S1 and mix. Then add water to adjust the moisture content to obtain the base material.
[0057] S3. Add *Phanerochaete chrysosporium* suspension and *Bacillus subtilis* activation solution to the substrate obtained in S2 and mix well to obtain fermentation material; the ratio of the amount of *Phanerochaete chrysosporium* suspension added to the mass of the substrate is 10.5 mL / kg; the ratio of the amount of *Bacillus subtilis* activation solution added to the mass of the substrate is 9.5 mL / kg.
[0058] S4. Compost the fermented material obtained in S3 for 35 days. During the composting process, turn the compost pile 3 times a week for the first two weeks and 2 times a week thereafter to obtain compound organic fertilizer.
[0059] Experimental Example: Experimental Subjects: Compound organic fertilizer samples prepared in Examples 1-3 and Comparative Examples 1-3.
[0060] Experimental item: Seed germination index determination experiment.
[0061] Experimental Methods: Samples were taken from the compost at days 0, 3, 7, 14, 21, 28, and 35. A multi-point sampling method was used, taking samples from the top, middle, and bottom of three sections (left, middle, and right) of the compost and mixing them. 5.00 g of fertilizer sample was weighed into a 250 mL Erlenmeyer flask, 100 mL of deionized water was added, and the flask was sealed with a rubber stopper. The flask was then shaken at 200 rpm for 1 hour, filtered, and the extract was obtained. 10 mL of the extract was added to a 15 cm petri dish lined with filter paper. 20 plump white radish seeds were evenly placed on the filter paper and placed in a dark incubator at (25±1)℃ for 48 hours. The germination rate was calculated, and the root length was measured. Each sample was repeated three times, with distilled water used as a control. The calculation formula was: Seed germination index = (Seed germination rate in extract × Root length) / (Seed germination rate in distilled water × Root length) × 100%.
[0062] Experimental results: see Table 1.
[0063] Table 1. Experimental Results Data for the Experimental Case
[0064] Results Analysis: Combining the data in Table 1 and... Figure 1 The analysis focused on Example 1 and Comparative Examples 1-3: Specifically, by comparing Comparative Example 1 and Comparative Example 2, it can be seen that, compared with Comparative Example 1, the addition of oxidative modified straw biochar in Comparative Example 2 alone resulted in a decrease in the composting rate (the seed germination index-composting time curve decreased), especially in the early stage of composting (before 21 days).
[0065] This is mainly because, when oxidized modified straw biochar is introduced alone, on the one hand, it can have a positive effect: the porous structure of oxidized modified straw biochar can directly increase the porosity of the compost pile, improve the ventilation conditions of the pile in the long term, provide sufficient oxygen for aerobic microorganisms, promote / accelerate the aerobic composting process, and increase the composting rate to reduce phytotoxicity more quickly; on the other hand, it can also have a negative effect: the well-developed porous structure of oxidized modified straw biochar is easily blocked by the adsorption of moisture and organic matter in the early stage of composting, which obstructs air circulation in local areas, forms an anaerobic microenvironment, promotes the production of organic acids, leads to increased phytotoxicity, and inhibits seed germination (reduces the germination index); and for the entire composting cycle, the negative effect outweighs the positive effect. Therefore, introducing oxidized modified straw biochar alone will actually lead to a decrease in the composting rate, requiring a longer composting time to reach complete composting.
[0066] Specifically, by comparing Comparative Example 1 and Comparative Example 3, it can be seen that compared with Comparative Example 1, the addition of ammonified superphosphate in Comparative Example 3 significantly improved the composting rate (the seed germination index-composting time curve increased).
[0067] This is mainly because when ammonified superphosphate is introduced alone (ammoniation eliminates the acidity of superphosphate to avoid inhibiting microbial activity due to its low pH during addition), the water-soluble phosphorus it provides can directly meet the needs of microorganisms (Bacillus subtilis, Protozoa chrysospora), quickly activate microbial activity, accelerate the degradation of cellulose and lignin, shorten the decomposition cycle of organic matter, and improve the decomposition rate.
[0068] In comparison with Example 1, it can be seen that the simultaneous introduction of oxidized modified straw biochar and ammonified superphosphate can produce a synergistic effect, synergistically improving the composting rate.
[0069] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a compound organic fertilizer, characterized in that, Includes the following steps: S1. By weight, mix 27-30 parts of rice straw, 9-10 parts of wheat bran and 8-9 parts of animal manure to obtain the initial raw materials; S2. Add 0.85-0.9 parts of oxidized modified straw biochar and 0.5-0.55 parts of ammonified superphosphate to the initial raw material obtained in S1, mix them, and adjust the moisture content to 53±3% to obtain the base material. S3. Add *Phanerochaete chrysosporium* suspension and *Bacillus subtilis* activation solution to the substrate obtained in S2 and mix well to obtain fermentation material; the ratio of the amount of *Phanerochaete chrysosporium* suspension added to the substrate is 10-11 mL / kg; the ratio of the amount of *Bacillus subtilis* activation solution added to the substrate is 9-10 mL / kg. S4. The fermented material obtained in S3 is composted for more than 28 days to obtain the compound organic fertilizer.
2. The method for preparing compound organic fertilizer according to claim 1, characterized in that, The oxidized modified straw biochar is prepared by carbonizing rice straw at 500±10℃ for 2-2.3h, followed by oxidation treatment with 28-30wt% hydrogen peroxide aqueous solution for 1.8-2.2h.
3. The method for preparing compound organic fertilizer according to claim 1, characterized in that, The preparation method of the aminated superphosphate is as follows: superphosphate and urea are mixed at a mass ratio of 1:(0.1-0.15), water is added to a moisture content of 21-24%, and the mixture is stirred and reacted at 80-85℃ for 2-2.5 hours. After drying, it is pulverized to obtain the final product.
4. The method for preparing compound organic fertilizer according to claim 1, characterized in that, The preparation method of the *Phanerochaete chrysosporium* suspension is as follows: *Phanerochaete chrysosporium* is inoculated onto PDA medium and cultured for 3 days. Spores are scraped off to prepare a bacterial suspension, and its concentration is adjusted to 2-3 × 10⁻⁶. 8 The result is obtained as [number] cells / mL.
5. The method for preparing compound organic fertilizer according to claim 1, characterized in that, The preparation method of the Bacillus subtilis activation solution is as follows: by weight, mix 1 part of Bacillus subtilis with 1 part of brown sugar and 23-25 parts of warm water at 32-35℃, and let it stand for 28-32 minutes to activate.
6. The method for preparing compound organic fertilizer according to claim 5, characterized in that, The viable count of the Bacillus subtilis was 4.7-5.4 × 10⁻⁶. 8 / g.
7. The method for preparing compound organic fertilizer according to claim 1, characterized in that, In S1, the animal excrement includes pig manure, chicken manure and sheep manure, and the mass ratio of the three is 1:(1-1.5):(1-1.5).
8. The method for preparing compound organic fertilizer according to claim 1, characterized in that, In S4, during the composting fermentation period, the compost pile should be turned over 2-3 times a week for the first two weeks, and then 1-2 times a week thereafter.
9. A compound organic fertilizer, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 8.