Preparation method of acidic soil straw compost product modifier

Abstract

The invention provides a preparation method of an acid soil straw compost product modifier. The method comprises the following steps: 1) collecting river suspended particulate matters in an acid soil area; 2) placing the river suspended particulate matters in a container, and adding a proper amount of KNO3 solution and NaHCO3 solution to form a mixed solution; 3) maintaining dissolved oxygen in the mixed solution through aeration, and culturing for a certain time; (4) supplementing a carbon source into the cultured mixed solution, and then continuously culturing for a certain time to form a primary compost product; step 5) adding straws and CaO into the preliminary compost product, then adding a certain amount of pure water, and continuing to culture for a certain time to form a compost mixture containing flora; (6) continuing to add the straws into the compost mixture containing the flora, and decomposing the straws by utilizing the flora to obtain the acidic soil straw compost product modifier; the acidic soil straw compost product improver prepared by the invention can be suitable for improving acidic soil.

Description

Technical Field

[0001] The present invention relates to a preparation method of an acidic soil straw compost product improver, belonging to the technical fields of solid waste resource utilization and acidic soil improvement. Background Art

[0002] At present, suspended particles in rivers and lakes are one of the main causes of water turbidity. They are not only an important source of water pollution but also have potential value for resource utilization. In recent years, with the development of environmental protection technologies and the concept of circular economy, related resource utilization technologies have gradually matured. The main directions include building materials (such as the preparation of sintered bricks / ceramsite, permeable pavement materials), soil improvers (such as organic-inorganic compound fertilizers, saline-alkali land remediation materials), energy utilization (such as pyrolysis gasification, anaerobic fermentation to produce biogas), material recovery (such as the extraction of elements such as silicon and aluminum, the preparation of adsorption materials), and ecological restoration (such as artificial wetland substrates, bottom mud covering materials), etc.

[0003] Meanwhile, the problem of agricultural straw resource utilization is also one of the major challenges faced by agricultural development. How to quickly degrade straw and improve the agricultural application effect of its degradation products has become a hot topic in the field of agricultural scientific research. As a rich organic substance, straw can be converted into resources such as organic fertilizers, feeds, and energy after reasonable treatment, improving soil fertility, reducing the use of chemical fertilizers, and even providing raw materials for the energy industry. For example, using straw as biochar can not only improve soil structure and fertility but also play a positive role in emission reduction. At present, research mainly focuses on how to promote the rapid degradation of straw through methods such as microbial degradation, enzymatic hydrolysis technology, and pyrolysis technology, and explore efficient utilization methods of its degradation products.

[0004] Common methods for improving acidic soil at present include: applying lime materials, organic material improvement, biological improvement technology, mineral material improvement, and chemical improvers. There are even technologies that combine the application of lime, organic matter, and microbial agents, combined with tillage measures (such as deep subsoiling) for synergistic improvement. However, the continuous addition of chemical materials is not strong; the integration of multiple technologies is difficult for farmers to operate and the input cost doubles (such as microbial agents + organic fertilizers + lime), resulting in limited promotion; the microbial agents used in bioremediation often have poor application effects due to different regional environments and weak applicability.

[0005] Therefore, if the river suspended particles can be combined with straw resource utilization and applied to acidic soil improvement, it will be able to well solve the respective dilemmas of river suspended particles, straw resource utilization, and acidic soil improvement at the same time. Summary of the Invention

[0006] The present invention provides a method for preparing an acidic soil straw compost product improver, aiming to combine river suspended particles with straw resources to prepare an acidic soil straw compost product improver that can be applied to acidic soil improvement.

[0007] The technical solution of the present invention: A method for preparing an acidic soil straw compost product improver, the method comprising:

[0008] Step 1) Collect river suspended particles in acidic soil areas;

[0009] Step 2) Place the river suspended particles in a container, and add appropriate amounts of KNO3 solution and NaHCO3 solution to form a mixed solution;

[0010] Step 3) Maintain the dissolved oxygen in the mixed solution by aeration, and cultivate for a certain period of time to form a cultivated mixed solution;

[0011] Step 4) Supplement a carbon source to the cultivated mixed solution, and then continue to cultivate for a certain period of time to form a preliminary compost product;

[0012] Step 5) Add straw and CaO to the preliminary compost product to form a compost mixture, then add a certain amount of pure water and continue to cultivate for a certain period of time to form a compost mixture containing bacteria; the bacteria obtained here have the function of cellulose degradation and can produce alkaline substances.

[0013] Step 6) Continuously add straw to the compost mixture containing bacteria, and use the bacteria to decompose the straw to obtain an acidic soil straw compost product improver.

[0014] Furthermore, the concentration of KNO3 in the KNO3 solution is 5 mmol / L to 20 mmol / L; the concentration of NaHCO3 in the NaHCO3 solution is 0.1 mol / L to 1 mol / L; after adding appropriate amounts of KNO3 solution and NaHCO3 solution to form a mixed solution, the pH value is adjusted to 8.0 - 9.0; in step 3), the dissolved oxygen in the mixed solution is maintained by aeration ≥ 5 mg / L.

[0015] Furthermore, in step 3), cultivating for a certain period of time at room temperature to form a cultivated mixed solution specifically means cultivating for one week at room temperature to form a cultivated mixed solution; step 5) is repeated 1 - 2 times and then step 6) is performed; in step 6), the ratio of adding straw to the compost mixture containing bacteria is the mass of the compost mixture containing bacteria: the mass of straw = 1:4.

[0016] Furthermore, supplementing a carbon source to the cultivated mixed solution specifically means supplementing cellulose filter paper to the cultivated mixed solution.

[0017] Further, supplementing a carbon source to the culture mixture specifically means supplementing cellulose filter paper equivalent to 1% - 10% of the mass of the culture mixture as the only carbon source during the process of forming the preliminary compost product.

[0018] Further, the mass ratio of the straw added in step 5) to the carbon source supplemented in step 4) is 50:(0.5 - 2), and the mass ratio of the added CaO to the straw is 1:1000 - 5:1000.

[0019] Further, a nitrogen source is added simultaneously with the straw and CaO in step 5) to adjust the carbon-nitrogen ratio in the compost mixture to (25 - 30):1.

[0020] Further, the straw added in step 7) is the same kind of straw as that added in step 5).

[0021] Further, the straw is any one kind of straw or a combination of several kinds of straws among rice straw, corn straw, rapeseed straw, wheat straw, and soybean straw.

[0022] Further, in step 5), straw and CaO are added to the preliminary compost product to form a compost mixture, and then a certain amount of pure water is added and the mixture is continuously cultured for a certain period of time. Specifically, it includes: adding straw and CaO to the preliminary compost product to form a compost mixture, then adding a certain amount of pure water to keep the moisture content of the compost mixture between 60% and 70%, and then continuously culturing for 15 days to 60 days.

[0023] Advantages of the present invention:

[0024] 1) The present invention provides a method for the resource utilization of river suspended particles and straw. The acidic soil straw compost product improver prepared by the present invention can be applied to the improvement of acidic soil;

[0025] 2) The present invention collects river suspended particles in acidic soil areas, and the cultured microbial flora adapts to the environment with good effects. The method of the present invention is simple to operate and easy to promote. Description of the drawings

[0026] Appendix Figure 1It is a comparison chart of the effects of growing plants after using acidic soil (corresponding to CK in the attached drawings), using conventional rice straw compost products (corresponding to RS1 - RS3 in the attached drawings) to improve acidic soil, using conventional corn straw compost products (corresponding to CS1 - CS3 in the attached drawings) to improve acidic soil, using the acidic soil rice straw compost product improver prepared by the present invention (corresponding to SPMRS1 - SPMRS3 in the attached drawings) to improve acidic soil, and using the acidic soil corn straw compost product improver prepared by the present invention (corresponding to SPMCS1 - SPMCS3 in the attached drawings) to improve acidic soil.

[0027] Appendix Figure 2 It is a comparison chart of the effects of using acidic soil (corresponding to CK in the attached drawings), using conventional rice straw compost products (corresponding to RS1 - RS3 in the attached drawings) to improve acidic soil, using conventional corn straw compost products (corresponding to CS1 - CS3 in the attached drawings) to improve acidic soil, using the acidic soil rice straw compost product improver prepared by the present invention (corresponding to SPMRS1 - SPMRS3 in the attached drawings) to improve acidic soil, and using the acidic soil corn straw compost product improver prepared by the present invention (corresponding to SPMCS1 - SPMCS3 in the attached drawings) to improve acidic soil (soil quality: improver quality = 50:1). Appendix Figure 3 It is a comparison chart of stacked columnar diagrams of the microbial community structures detected in ordinary acidic soil (corresponding to CK in the attached drawings), the microbial community structures detected in the soil after improving acidic soil with conventional corn straw compost products (corresponding to CS1 - CS3 in the attached drawings), and the microbial community structures detected in the soil after improving acidic soil with the acidic soil corn straw compost product improver prepared by the present invention (corresponding to SPMCS1 - SPMCS3 in the attached drawings) (soil quality: improver quality = 50:1).

[0028] Appendix Figure 4 It is the pH value measurement results after two - week degradation of corn straw by different microbial species screened from the microbial flora obtained in the present invention.

[0029] Appendix Figure 5 It is the straw degradation rate chart after two - week degradation of corn straw by different microbial species screened from the microbial flora obtained in the present invention. Detailed implementation methods

[0030] A preparation method of an acidic soil straw compost product improver, the method comprising:

[0031] Step 1) Collect river suspended particles in acidic soil areas;

[0032] Step 2) Place the river suspended particulate matter in a container, add an appropriate amount of KNO3 solution and NaHCO3 solution to form a mixed solution, and adjust the pH value to 8.0 - 9.0; the concentration of KNO3 in the KNO3 solution is preferably 5 mmol / L to 20 mmol / L, and the concentration of KNO3 in the KNO3 solution is further preferably 10 mmol / L; the concentration of NaHCO3 in the NaHCO3 solution is preferably 0.1 mol / L to 1 mol / L, and the concentration of NaHCO3 in the NaHCO3 solution is further preferably 0.2 mol / L;

[0033] Step 3) Maintain the dissolved oxygen in the mixed solution ≥ 5 mg / L by aeration, and cultivate at room temperature for a certain period of time to form a post-cultivation mixed solution; preferably cultivate at room temperature for one week to form a post-cultivation mixed solution;

[0034] Step 4) Supplement a carbon source in the post-cultivation mixed solution, and then continue to cultivate for a certain period of time to form a preliminary compost product, preferably continue to cultivate for one week to form a preliminary compost product; the carbon source is preferably filter paper; the filter paper is preferably cellulose filter paper; preferably supplement cellulose filter paper equivalent to 1% - 10% of the mass of the post-cultivation mixed solution as the only carbon source during the formation of the preliminary compost product; further preferably supplement cellulose filter paper equivalent to 2% of the mass of the post-cultivation mixed solution as the only carbon source during the formation of the preliminary compost product;

[0035] Step 5) Add straw and CaO to the preliminary compost product to form a compost mixture, then add a certain amount of pure water to keep the moisture content of the compost mixture between 60% - 70%, and then continue to cultivate for 15 days - 60 days, further preferably continue to cultivate for 30 days; the mass ratio of the added straw to the cellulose filter paper is preferably 50:(0.5 - 2); the mass ratio of the added straw to the cellulose filter paper is further preferably 50:1; the mass ratio of the added CaO to the straw is 1:1000 - 5:1000; preferably add a nitrogen source while adding straw and CaO, and preferably adjust the carbon-nitrogen ratio in the compost mixture to (25 - 30):1, and the nitrogen source is preferably urea;

[0036] Step 6) After repeating Step 5) 1 - 2 times, obtain a flora with cellulose degradation function and capable of producing alkaline substances in the compost mixture to form a compost mixture containing the flora. Here, the produced flora can adapt to the alkaline environment provided by CaO; not repeating Step 5) will also obtain a flora with cellulose degradation function and capable of producing alkaline substances, and repeating Step 5) 1 - 2 times will more fully obtain a flora with cellulose degradation function and capable of producing alkaline substances;

[0037] Step 7) Continuously add straw to the compost mixture containing the microbial community. Preferably, add straw according to the ratio of the mass of the compost mixture containing the microbial community: the mass of straw = 1:4. Utilize the microbial community to decompose the straw to obtain an acidic soil straw compost product improver with a pH between 8.0 and 9.0. The acidic soil straw compost product improver is beneficial to the improvement of acidic soil. The straw added in step 7) and the straw added in step 5) are preferably the same kind of straw, and further preferably any one kind of straw or a combination of several kinds of straws selected from corn straw, wheat straw, rapeseed straw, soybean straw, and rice straw. When the straw added in step 7) and step 5) is rice straw, the acidic soil rice straw compost product improver prepared by the present invention is obtained. When the straw added in step 7) and step 5) is corn straw, the acidic soil corn straw compost product improver prepared by the present invention is obtained.

[0038] The acidic soil straw compost product improver obtained by the present invention has a good improvement effect on acidic soil. The microbial flora in the microbial community can adapt to the local environment of acidic soil areas. In addition, the microbial flora can adapt to the CaO environment and can combine with CaO to improve acidic soil, effectively maintaining the improvement effect of acidic soil. The acidic soil straw compost product improver can also provide nutrients for acidic soil crops, increase plant biomass, and increase farmers' income.

[0039] The present invention can be used in areas with a need for acidic soil improvement. First, it is preferred to collect river suspended particles in acidic soil areas. Since river suspended particles are carriers for multi-interface material exchange between land sources, aquatic environments, and sediments, the microbial communities carried in river suspended particles have the following irreplaceability after long-term natural selection: The microbial communities in river suspended particles have adapted to the degradation of complex organic matters (such as cellulose, lignin, and humus), and there is a co-metabolic network (such as fungal-bacterial interaction) within the microbial communities, which is difficult to replicate by laboratory pure culture strains. The microbial communities in river suspended particles have been exposed to natural rivers for a long time. Some natural rivers may contain pollutants (such as heavy metals and pesticides). The microbial communities in river suspended particles are more likely to adapt to adverse environments after long-term exposure to natural rivers. In addition, in the main distribution areas of acidic soil, the soil pH value is mostly between 4.0 and 6.5. When the soil pH is lower than 5.5, it is considered that improvement and treatment are needed. Usually, the pH of rivers is neutral or slightly acidic, which is higher than the soil pH. Therefore, the function of alkali-producing bacteria in river suspended particles is not easily inhibited and is more easily cultured.

[0040] Apply the acidic soil straw compost product improver prepared by the present invention and the conventional straw compost product in the same addition method to the improvement of acidic soil respectively. After improving the same acidic soil and then planting the same plants for comparison, as shown in the appendix Figure 1The leftmost figure shows the growth of plants directly planted in acidic soil (with corn planted in it) as a reference group (CK group); Figure 1 The figure in the middle shows the growth of plants planted after improving acidic soil with conventional rice straw compost products (RS1 - RS3) and the growth of plants planted after improving acidic soil with conventional corn straw compost products (CS1 - CS3); Figure 1 The figures other than the reference group show the growth of plants planted after improving acidic soil with the acidic soil rice straw compost product improver (SPMRS1 - SPMRS3) prepared by the present invention and the growth of plants planted after improving acidic soil with the acidic soil corn straw compost product improver (SPMCS1 - SPMCS3) prepared by the present invention; From the comparison in Figure 1 it can be seen that the growth of corn planted after improving acidic soil with the acidic soil straw compost product improver prepared by the present invention is significantly better than that of corn planted after improving acidic soil with conventional straw compost products, indicating that the acidic soil straw compost product improver prepared by the present invention can not only improve acidic soil, but also improve soil structure and fertility, and promote the healthy growth of crops. Figure 1 The comparison in the figure shows that the growth of corn planted after improving acidic soil with the acidic soil straw compost product improver prepared by the present invention is significantly better than that of corn planted after improving acidic soil with conventional straw compost products, indicating that the acidic soil straw compost product improver prepared by the present invention can not only improve acidic soil, but also improve soil structure and fertility, and promote the healthy growth of crops.

[0041] In Figure 2 the figure, the comparison of the improvement effects of improving acidic soil with conventional straw compost products and different acidic soil straw compost product improvers prepared by the present invention is shown, and the corresponding improved soils are respectively used for planting corn for comparison; Figure 2 In the figure, CK corresponds to the growth of corn directly planted in unimproved acidic soil, RS1 - RS3 and CS1 - CS3 respectively correspond to the growth of corn planted after improving acidic soil with conventional rice straw compost products and conventional corn straw compost products, and SPMRS1 - SPMRS3 and SPMCS1 - SPMCS3 respectively correspond to the growth of corn planted after improving acidic soil with the acidic soil rice straw compost product improver prepared by the present invention and the acidic soil corn straw compost product improver prepared by the present invention; From Figure 2It can be seen that after the acidic soil is improved by using the conventional rice straw compost product, the pH value of the soil is between 5.62 and 5.84. After the acidic soil is improved by using the acidic soil rice straw compost product improver prepared by the present invention, the pH value of the soil is between 6.15 and 6.21. After the acidic soil is improved by using the conventional corn straw compost product, the pH value of the soil is between 5.78 and 5.99. After the acidic soil is improved by using the acidic soil corn straw compost product improver prepared by the present invention, the pH value of the soil is between 6.24 and 6.30. It is obvious that the improvement effect of the acidic soil straw compost product improver prepared by the present invention on the acidity of the acidic soil is better. After the corresponding improved soil is used to plant corn under the same conditions and the single corn plants are measured and compared, under the same growth time period and environmental conditions, after the acidic soil is improved by using the conventional rice straw compost product, the above-ground dry weight of the corn is between 4.410 and 5.033 g. After the acidic soil is improved by using the acidic soil rice straw compost product improver prepared by the present invention, the above-ground dry weight of the corn is between 5.739 and 5.977 g. After the acidic soil is improved by using the conventional corn straw compost product, the above-ground dry weight of the corn is between 5.067 and 5.233 g. After the acidic soil is improved by using the acidic soil corn straw compost product improver prepared by the present invention, the above-ground dry weight of the corn is between 6.112 and 6.378 g. It can be seen that the above-ground dry weight of the corn grown in the soil improved by using the conventional straw compost product for the acidic soil is significantly lower than that of the corn grown in the soil improved by using different acidic soil straw compost product improvers prepared by the present invention for the acidic soil. It shows that the acidic soil straw compost product improver prepared by the present invention can not only improve the acidic soil, but also improve the soil structure and fertility, and promote the healthy growth of crops.

[0042] Through screening and verification of the strains, it is found that the acidic soil straw compost product improver prepared by the present invention contains one or several of the microorganisms Bacillus subtilis, Bacillus wiedmannii, Acinetobacter baumannii, Enterobacter sakazakii, Enterobacter cloacae, Enterobacter SP., Escherichia coli, Enterobacter bugandensis. After laboratory culture, it is confirmed that it has the functions of promoting straw degradation and increasing the pH value of the compost product. The microorganisms at the species level cultured in the laboratory are corresponding as shown in the appendix Figure 3The detected genus-level microorganisms, Bacillus subtilis and Bacillus wiedmannii are species-level microorganism names and they belong to the genus Bacillus; Acinetobacter baumannii is a species-level microorganism name and it belongs to the genus Acinetobacter; Enterobacter sakazakii, Enterobacter cloacae, Enterobacter SP., Escherichia coli, and Enterobacter bugandensis belong to the genus Enterobacter.

[0043] Appendix Figure 4 , Appendix Figure 5 They are respectively the pH value measurement and the corn straw degradation rate measurement after two weeks of degradation of different microbial species screened from the microbial community obtained in step 6) of the method of the present invention; from Appendix Figure 4 From the pH value measurement results in, it can be seen that each microbial species screened from the different strains formed in the present invention can produce alkaline substances after decomposing corn straw, increase the pH of the straw compost product conditioner, and can obtain an acidic soil straw compost product conditioner with a pH greater than 7, ensuring that the overall microbial community obtained from step 6) can obtain an acidic soil straw compost product conditioner with a pH between 8.0 and 9.0 after decomposing corn straw; from Appendix Figure 5 It can be seen that each microbial species screened from the different strains formed in the present invention has a good degradation effect on corn straw, ensuring that the overall microbial community obtained from step 6) decomposes straw more effectively, can degrade and convert corn straw into resources such as organic fertilizers and feeds, is beneficial to using straw to improve soil fertility, reduce the use of chemical fertilizers, and even provide raw materials for the energy industry.

[0044] As shown in Appendix Figure 3 is a comparison of stacked column charts of the microbial community structures detected in ordinary acidic soil (corresponding to CK in the attached figure), the microbial community structures detected in the soil after improving acidic soil with conventional corn straw compost products (corresponding to CS in the attached figure), and the microbial community structures detected in the soil after improving acidic soil with the acidic soil corn straw compost product conditioner prepared in the present invention (corresponding to SPMCS in the attached figure); from Appendix Figure 3It can be seen from the above that the difference in the relative abundance of microorganisms detected in the acidic soil improved by the conventional corn straw compost product is relatively small compared with that detected in the ordinary acidic soil, indicating that the conventional corn straw compost product has a relatively small impact on the relative abundance of microorganisms in the acidic soil after improvement. However, the difference in the relative abundance of microorganisms detected in the acidic soil improved by the acidic soil corn straw compost product improver prepared by the present invention is obvious compared with that detected in the ordinary acidic soil, indicating that the impact of the acidic soil corn straw compost product improver prepared by the present invention on the microbial community structure in the acidic soil is significantly higher than that of the conventional corn straw compost product.

Claims

1. A preparation method of an acidic soil straw compost product improver, characterized in that Including: Step 1) Collect river suspended particulate matter in acidic soil areas; Step 2) Place the river suspended particulate matter in a container, and add an appropriate amount of KNO3 solution and NaHCO3 solution to form a mixed solution; Step 3) Maintain the dissolved oxygen in the mixed solution by aeration, and culture for a certain period of time to form a cultured mixed solution; Step 4) Supplement a carbon source in the cultured mixed solution, and then continue to culture for a certain period of time to form a preliminary compost product; Step 5) Add straw and CaO to the preliminary compost product to form a compost mixture, then add a certain amount of pure water and continue to culture for a certain period of time to form a compost mixture containing bacteria; Step 6) Continuously add straw to the compost mixture containing bacteria, and use the bacteria to decompose the straw to obtain an acidic soil straw compost product improver.

2. The preparation method of an acidic soil straw compost product conditioner according to claim 1, characterized in that The concentration of KNO3 in the KNO3 solution is 5 mmol / L to 20 mmol / L; the concentration of NaHCO3 in the NaHCO3 solution is 0.1 mol / L to 1 mol / L; after adding an appropriate amount of KNO3 solution and NaHCO3 solution to form a mixed solution, adjust the pH value to 8.0 - 9.0; in step 3), maintain the dissolved oxygen in the mixed solution ≥ 5 mg / L by aeration.

3. The preparation method of an acidic soil straw compost product improver according to claim 1, characterized in that In step 3), culturing for a certain period of time to form a cultured mixed solution specifically means culturing at room temperature for one week to form a cultured mixed solution; step 5) is repeated 1 - 2 times and then step 6) is carried out; in step 6), the ratio of adding straw to the compost mixture containing bacteria is: the mass of the compost mixture containing bacteria : the mass of straw = 1 :

4.

4. The preparation method of an acidic soil straw compost product conditioner according to claim 1, characterized in that Supplementing a carbon source in the cultured mixed solution specifically means supplementing cellulose filter paper in the cultured mixed solution.

5. The preparation method of an acidic soil straw compost product conditioner according to claim 1, characterized in that Supplementing a carbon source in the cultured mixed solution specifically means supplementing cellulose filter paper equivalent to 1% - 10% of the mass of the cultured mixed solution as the only carbon source during the process of forming the preliminary compost product.

6. The preparation method of an acidic soil straw compost product conditioner according to claim 1, characterized in that In step 5), the mass ratio of the added straw to the supplemented carbon source in step 4) is 50 : (0.5 - 2), and the mass ratio of the added CaO to the straw is 1 : 1000 - 5 : 1000.

7. The preparation method of an acidic soil straw compost product conditioner according to claim 1, characterized in that In step 5), while adding straw and CaO, a nitrogen source is also added to adjust the carbon-nitrogen ratio in the compost mixture to (25 - 30) :

1.

8. The preparation method of an acidic soil straw compost product conditioner according to claim 1, characterized in that The straw added in step 7) is the same kind of straw as the straw added in step 5).

9. The preparation method of an acidic soil straw compost product conditioner according to claim 1, characterized in that The straw is any one kind of straw or a combination of several kinds of straws among rice straw, corn straw, rape straw, wheat straw, and soybean straw.

10. The preparation method of an acidic soil straw compost product improver according to claim 1, characterized in that Step 5) adding straw and CaO to the preliminary compost product to form a compost mixture, then adding a certain amount of pure water and continuing to culture for a certain period of time specifically includes: adding straw and CaO to the preliminary compost product to form a compost mixture, then adding a certain amount of pure water to keep the moisture content of the compost mixture between 60% - 70%, and then continuing to culture for 15 days - 60 days.

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