A low-carbon, multifunctional bio-compound fertilizer made from straw, its preparation method and application

Abstract

This invention belongs to the field of crop straw treatment technology, specifically disclosing a low-carbon, multifunctional bio-compound fertilizer made from straw, its preparation method, and its application. The bio-compound fertilizer provided by this invention, through the scientific formulation of functional microbial strains and the use of microbial immobilization technology to load the fertilizer, combines highly efficient strains with EM bacteria and nitrification inhibitors, thereby improving the straw return-to-field effect, sequestering carbon and reducing emissions, and promoting sustainable agricultural development.

Description

Technical Field

[0001] This invention belongs to the field of crop straw treatment technology, specifically relating to a low-carbon, multifunctional bio-compound fertilizer made from straw, its preparation method, and its application. Background Technology

[0002] In current agricultural practices, in-situ straw return to the field, as an important measure for resource recycling and soil fertility improvement, is widely adopted but still faces multiple challenges. First, the natural degradation process of straw is slow, mainly due to its high content of cellulose and hemicellulose, components that are difficult for soil microorganisms to directly utilize, leading to delayed nutrient release and affecting the timely absorption of nutrients by crops. Second, pathogens and insect eggs carried in straw become potential sources of pests and diseases for subsequent crops after straw return, increasing the difficulty and cost of pest and disease control. Third, insufficient regulation of nitrogen conversion and greenhouse gas emissions during straw return results in significant nitrogen loss and increased greenhouse gas emissions, adversely affecting the environment. Fourth, in actual transportation, microbial fertilizers still suffer from unstable fertilizer efficacy and short shelf life. Summary of the Invention

[0003] In view of the numerous problems existing in the aforementioned background technology, this invention aims to provide a straw composting agent, its preparation method, and its application. This invention prepares a straw composting agent by combining a compound functional microbial inoculant powder with EM bacteria and nitrification inhibitors. The straw composting agent of this invention can achieve rapid straw composting, effective nutrient conversion, significant improvement of the soil micro-ecological environment, stable fertilizer effect, and soil carbon sequestration. This innovative technology not only reduces agricultural production costs but also promotes the improvement of farmland fertility and the achievement of carbon sequestration and emission reduction goals, providing strong support for sustainable agricultural development.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] One of the technical solutions is a straw composting agent, which, by weight, comprises the following components: 10-20 parts corn straw, 50-60 parts compound functional microbial inoculant powder, 10-20 parts nitrification inhibitor, and 10-20 parts EM bacteria.

[0006] The compound functional microbial inoculant powder, by weight, is composed of the following single-functional microbial inoculant powders: 20-30 parts of functional microbial inoculant powder 1 (Staphylococcus xylose) powder, 20-30 parts of functional microbial inoculant powder 2 (Procambarus chrysosporus) powder, and 1-5 parts of functional microbial inoculant powder 3 (nitrite oxidizing bacteria) powder.

[0007] The nitration inhibitor is selected from any one of pyridine, dicyandiamide, and 3,4-dimethylpyrazole phosphate (DMPP).

[0008] The EM bacteria are rich in a variety of beneficial microorganisms, such as photosynthetic bacteria, lactic acid bacteria, yeast, fermenting filamentous fungi, and actinomycetes, which can improve the soil micro-ecological environment, promote plant growth, and reduce the occurrence of diseases.

[0009] The length of the corn stalks is 3-5cm.

[0010] The preparation method of the functional microbial inoculant powder includes the following steps:

[0011] S1. Inoculate the functional microbial agent into the compound culture medium and activate it for 24-48 hours. The activation temperature for Staphylococcus aureus is 25-30℃, the activation temperature for Phanerochaete chrysosporium is 28-32℃, and the activation temperature for nitrite oxidizing bacteria is 30-35℃, so that the strains reach the logarithmic growth phase and preserve the bacterial solution.

[0012] S2. Mix the bacterial solution obtained in step S1 with biochar, shake to adsorb, pass through a 200-mesh sieve, wash, dry, and pulverize to obtain functional microbial agent raw powder.

[0013] Further, in step S2, the biochar is nitrogen-phosphorus-loaded biochar; preferably, the preparation method of the biochar is as follows: first, corn stalks are calcined at high temperature to obtain biochar, then the biochar is added to a mixed solution containing urea and diammonium hydrogen phosphate, ultrasonically treated for 2 hours, dried, and the solid powder is pyrolyzed at 600°C for 30 minutes to obtain nitrogen-phosphorus-loaded biochar; wherein, the mass ratio of urea, diammonium hydrogen phosphate and biochar is 2-3:4-5:10.

[0014] Furthermore, the conditions for obtaining biochar from corn stalks by high-temperature calcination are: pyrolysis at 600℃ for 1 hour.

[0015] Furthermore, the adsorption conditions were: constant temperature adsorption at 25-35℃ and 160-220r / min for 24-48 hours.

[0016] Furthermore, the bacterial solution and biochar were mixed at a ratio of 10-15 mL: 1 g.

[0017] Further, in step S1, each liter of the composite culture medium comprises: 250-300g glucose, 150-200g soybean meal powder, 100-120g magnesium sulfate, 10-20g corn stalk powder, 30-50g potassium dihydrogen phosphate, 8-10g vitamin B1, and the balance being water, wherein the pH of the composite culture medium is 7.0. The corn stalk powder has a particle size that passes through a 60-100 mesh sieve.

[0018] Technical Solution Two: The preparation method of the above-mentioned straw composting agent involves taking 10-20 parts of corn straw, 50-60 parts of compound functional microbial inoculant powder, 10-20 parts of nitrification inhibitor, and 10-20 parts of EM bacteria by weight, mixing and stirring evenly to obtain the straw composting agent.

[0019] Technical solution three: the application of the above-mentioned straw composting agent and the straw composting agent prepared by the above method in in-situ straw return to the field, carbon sequestration, and soil nutrient enhancement. The straw composting agent is suitable for straw from gramineous crops. The soil nutrients refer to one or more of organic matter, available phosphorus, and available potassium.

[0020] The composite functional microbial agent powder, a key component of the straw composting agent provided by this invention, is activated by inoculating the functional microbial agent into a composite culture medium. Corn straw powder added to the composite culture medium acts as an inducer to enhance the cellulose-degrading ability of the microbial agent, significantly strengthening the cellulose-degrading capacity of the cultured microorganisms. This method improves the cellulose-degrading ability of the straw composting agent and also significantly reduces the cost of preparing the straw composting agent. Glucose, as a carbon source, provides the main nutrients for the growth of the microbial agent; soybean meal powder, as a nitrogen source, provides the nitrogen element required for the synthesis of proteins and other cellular substances by the microbial agent; magnesium sulfate, as an inorganic salt, provides magnesium ions required for enzyme activators in the microbial agent; potassium dihydrogen phosphate provides phosphorus and potassium sources for the microbial agent; and vitamin B1 promotes microbial metabolism.

[0021] After activation and cultivation, functional microbial agents are loaded onto nitrogen- and phosphorus-loaded biochar using microbial immobilization technology to obtain functional microbial agent raw powder. This method can achieve carbon sequestration, improve soil environmental quality (reduce organic carbon mineralization in soil), reduce soil greenhouse gas emissions, reduce fertilizer use, and promote crop yield, representing a new approach to carbon sequestration and emission reduction.

[0022] The straw composting agent provided by this invention not only effectively promotes the decomposition of straw and the conversion of nutrients, but also improves the soil micro-ecological environment through the action of compound functional microbial inoculant powder and EM bacteria, reducing the incidence of plant diseases and promoting healthy crop growth. Simultaneously, the addition of nitrification inhibitors helps reduce nitrogen loss and greenhouse gas emissions, achieving the goals of improving farmland fertility and carbon sequestration and emission reduction.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] This invention provides a straw composting agent. This straw composting agent, through the scientific formulation of functional microbial strains and the use of microbial immobilization technology to load and combine high-efficiency strains with EM bacteria and nitrification inhibitors, can improve the straw return to the field, fix carbon and reduce emissions, and promote sustainable agricultural development.

[0025] This invention promotes straw decomposition and nutrient conversion through scientific formulation: The straw composting agent is rich in microorganisms. *Staphylococcus xylosus* and *Phanerochaete chrysosporium* can rapidly decompose recalcitrant components in straw, such as cellulose and hemicellulose, accelerating the straw composting process. This allows nutrients in the straw to be quickly converted into forms that plants can absorb and utilize, such as ammonium nitrogen, nitrate nitrogen, phosphorus, and potassium, thereby improving soil fertility. Nitrite-oxidizing bacteria can effectively inhibit nitrification in the soil, reducing nitrogen fertilizer loss during the conversion to nitrate nitrogen. These three types of bacteria work together to enhance farmland fertility.

[0026] Improving the soil microecological environment: The addition of EM bacteria to the straw composting agent of this invention further enriches the soil microbial community, forming a favorable microecological system. These microorganisms, through competition and symbiosis, effectively inhibit the reproduction of pathogens and pests, reduce the incidence of plant diseases, and create a healthy soil environment for crop growth.

[0027] Reducing greenhouse gas emissions and nitrogen loss: The nitrification inhibitor and nitrite-oxidizing bacteria in the straw composting agent of this invention can effectively inhibit nitrification in the soil, reduce nitrogen fertilizer loss during the conversion to nitrate nitrogen, and simultaneously reduce the emission of greenhouse gases such as CH4. This not only improves the utilization rate of nitrogen fertilizer but also reduces environmental pollution, achieving the goals of improving farmland fertility and carbon sequestration and emission reduction.

[0028] Stable and long-term fertilizer effect: Immobilizing functional microbial strains on biochar allows the biochar's porous structure and adsorption properties to provide a favorable growth environment for the microorganisms and protect them from adverse external factors. Furthermore, biochar itself has a certain nutrient release capacity and soil-improving effect, creating a synergistic effect with microbial fertilizers.

[0029] In summary, the straw composting agent of this invention, through its unique formula and efficacy, effectively solves the problems existing in traditional straw return-to-field technology, providing strong support for sustainable agricultural development. This invention not only has significant economic and environmental benefits, but also has important value for widespread application. Detailed Implementation

[0030] The applicant will now provide a more detailed description of the technical solution of the present invention with reference to specific embodiments. It should be understood that the following content should not be construed as limiting the scope of protection of the present invention in any way.

[0031] Examples 1-3 below provide a microbial inoculant culture medium for straw composting agents. All raw materials used are commercially available products: glucose was purchased from Suzhou Quanding Chemical Technology Co., Ltd.; soybean meal powder was purchased from Shandong Hongwei Biotechnology Co., Ltd.; magnesium sulfate was purchased from Weifang Botai Chemical Co., Ltd.; potassium dihydrogen phosphate was purchased from Qingdao Hisense Biochemical Co., Ltd.; sodium tetraborate (pH buffer) was purchased from Hubei Rishengchang New Material Technology Co., Ltd.; and corn straw powder was obtained by crushing dried corn straw and passing it through a 100-mesh sieve.

[0032] Preparation Example 1

[0033] The preparation steps for the liquid culture medium for the straw composting agent provided in this example are as follows: Take 300g of glucose, 200g of soybean meal powder, 120g of magnesium sulfate, 20g of corn straw powder, 50g of potassium dihydrogen phosphate and 10g of vitamin B1, add an appropriate amount of water and mix, then add water to 1L, and adjust the pH to 7.0 using sodium tetraborate (pH buffer).

[0034] Preparation Example 2

[0035] The preparation steps for the liquid culture medium for the straw composting agent provided in this example are as follows: Take 250g of glucose, 150g of soybean meal powder, 100g of magnesium sulfate, 10g of corn straw powder, 30g of potassium dihydrogen phosphate and 8g of vitamin B1, add an appropriate amount of water and mix, then add water to 1L, and adjust the pH to 7.0 using sodium tetraborate (pH buffer).

[0036] Preparation Example 3

[0037] The preparation steps for the liquid culture medium for the straw composting agent provided in this example are as follows: Take 280g of glucose, 180g of soybean meal powder, 110g of magnesium sulfate, 15g of corn straw powder, 40g of potassium dihydrogen phosphate and 9g of vitamin B1, add an appropriate amount of water and mix, then add water to 1L, and adjust the pH to 7.0 using sodium tetraborate (pH buffer).

[0038] The following culture examples 1-3 provide a method for preparing functional microbial inoculant powders. The functional microbial inoculants used are as follows: *Staphvlococcus pseudooxylosus*, named XW-4, registered in GenBank, number OO443074.1; *Phanerochaetechrysosporium* CGMCC 5.0776, purchased from the Chinese Academy of Sciences Culture Collection Center; and nitrite-oxidizing bacteria: *Nitrobacter Winogradskyi* Y3-2, CCTCC NO: M2014203, purchased from the China Center for Type Culture Collection.

[0039] Cultivation Example 1

[0040] The method for preparing functional microbial inoculant powder provided in this culture example includes the following steps:

[0041] S1, Pre-culture

[0042] Staphylococcus pseudoxylosus (XW-4), Phanerochaete chrysosporium (CGMCC 5.0776), and nitrite-oxidizing bacteria were inoculated into the compound culture medium prepared in Preparation Example 1, respectively. The activation temperature of Staphylococcus pseudoxylosus was controlled at 25-30℃, the activation temperature of Phanerochaete chrysosporium was controlled at 28-32℃, and the activation temperature of nitrite-oxidizing bacteria (bacteria) was controlled at 30-35℃. The bacteria were activated and cultured for 24-48 hours to allow them to reach the logarithmic growth phase and the bacterial culture was preserved.

[0043] S2, Carbon-based Functional Microbial Fixative

[0044] The activated Staphylococcus xylose, Phanerochaete chrysospora, and nitrite-oxidizing bacteria solutions from step S1 were mixed with nitrogen-phosphorus-loaded biochar at a ratio of 10 mL: 1 g, and then the mixture was fixed by constant temperature shaking at 35 °C and 160 r / min for 24 h to obtain a carbon-based functional microbial fixative.

[0045] The preparation method of the nitrogen-phosphorus-loaded biochar is as follows: First, corn stalks are placed in a muffle furnace and pyrolyzed at 600℃ for 1 hour, then cooled to room temperature to obtain biochar; 2.17g of urea and 4.35g of diammonium hydrogen phosphate are weighed and dissolved in water, and the volume is adjusted to 1L with deionized water. Then, 10g of biochar is added, and the mixture is ultrasonically treated for 2 hours, dried, and the solid powder is placed in a muffle furnace and pyrolyzed at 600℃ for 30 minutes. After cooling to room temperature, the nitrogen-phosphorus-loaded biochar is obtained. The obtained nitrogen-phosphorus-loaded biochar material was analyzed by ICP, and the elemental ratio of C, N, and P was 0.5%:0.5%:1.

[0046] S3, Functional Microbial Agent Raw Powder

[0047] The carbon-based functional microbial fixative obtained in step S2 was filtered through a 200-mesh sieve, then slowly rinsed with 0.85% sterile physiological saline, dried at room temperature for 24 hours, and then pulverized into fine powder to obtain functional microbial inoculant powders: Staphylococcus xylose original powder, Protozoa chrysospora original powder, and nitrite oxidizing bacteria original powder.

[0048] Cultivation Example 2

[0049] Staphylococcus pseudoxylosus (XW-4), Phanerochaete chrysosporium (CGMCC 5.0776), and nitrite-oxidizing bacteria were inoculated into the compound culture medium prepared in Preparation Example 2, and the other operation steps were exactly the same as those in Culture Example 1.

[0050] Cultivation Example 3

[0051] Staphylococcus pseudoxylosus (XW-4), Phanerochaete chrysosporium (CGMCC 5.0776), and nitrite-oxidizing bacteria were inoculated into the compound culture medium prepared in Preparation Example 3, and the other operation steps were exactly the same as those in Culture Example 1.

[0052] Experimental testing

[0053] The number of viable bacteria and cellulase activity in the functional microbial inoculant powders obtained from culture examples 1 to 3 were detected, and the results are recorded in Table 1.

[0054] Table 1

[0055]

[0056] As shown in Table 1, the Staphylococcus aureus and Protozoa chrysospora powders obtained in Culture Example 1 exhibited the strongest fiber-degrading ability. Subsequent preparations of straw composting agents all utilized the Staphylococcus aureus, Protozoa chrysospora, and nitrite-oxidizing bacteria powders obtained in Culture Example 1.

[0057] Examples 1-3 below provide a method for preparing a straw composting agent; the *Staphylococcus xylostella* powder, *Phanerochaete chrysospora* powder, and nitrite-oxidizing bacteria powder used were prepared using the culture method described in Example 1. The corn straw used was dried corn straw, crushed into 5cm pieces. The nitrification inhibitor used was 3,4-dimethylpyrazole phosphate, purchased from Wuhan Jiyesheng Chemical Co., Ltd. The EM bacteria (powder) used was purchased from Shandong Junde Biotechnology Co., Ltd.

[0058] Example 1

[0059] The method for preparing the straw composting agent provided in this embodiment includes the following steps: First, take 15 kg of Staphylococcus aureus raw powder, 15 kg of Protozoa chrysospora raw powder, and 1 kg of nitrite oxidizing bacteria raw powder and mix them evenly to obtain a compound functional microbial agent raw powder; then take 5.2 kg of corn straw, 31 kg of compound functional microbial agent raw powder, 5.2 kg of nitrification inhibitor, and 5.2 kg of EM bacteria and mix them evenly to obtain the straw composting agent.

[0060] Example 2

[0061] The method for preparing the straw composting agent provided in this embodiment includes the following steps: First, take 12.5 kg of Staphylococcus aureus raw powder, 12.5 kg of Protozoa chrysospora raw powder, and 1.25 kg of nitrite oxidizing bacteria raw powder and mix them evenly to obtain a compound functional microbial agent raw powder; then take 4.38 kg of corn straw, 26.25 kg of compound functional microbial agent raw powder, 4.38 kg of nitrification inhibitor, and 4.38 kg of EM bacteria and mix them evenly to obtain the straw composting agent.

[0062] Example 3

[0063] The method for preparing the straw composting agent provided in this embodiment includes the following steps: First, take 10 kg of Staphylococcus aureus raw powder, 10 kg of Protozoa chrysospora raw powder, and 0.5 kg of nitrite oxidizing bacteria raw powder and mix them evenly to obtain a compound functional microbial agent raw powder; then take 3.42 kg of corn straw, 20.5 kg of compound functional microbial agent raw powder, 3.42 kg of nitrification inhibitor, and 3.42 kg of EM bacteria and mix them evenly to obtain the straw composting agent.

[0064] Experimental testing

[0065] A test field (4m*5m) was selected, and 10.0 kg of wheat straw was crushed into 5cm pieces and evenly spread in the field. The straw composting agent provided in Examples 1-3 was evenly applied to the field at a dosage of 2 kg per acre. The field was turned over to ensure even mixing of the straw and the composting agent. The initial moisture content of the fermentation material was controlled between 55% and 65% to promote microbial growth and prevent anaerobic fermentation caused by excessive moisture. The performance of the straw composting agents provided in Examples 1-3 was tested using this method. A blank control experiment was conducted using a field with straw laid out without the added composting agent. During the fermentation process, the pH value of the fermentation material was monitored and adjusted to 6.5-7.5 (if necessary, appropriate amounts of lime or potassium dihydrogen phosphate were added as regulators). The pile was turned over every 3 days to promote oxygen entry into the pile and accelerate microbial activity. After a period of fermentation, when the pile temperature gradually decreases, the color darkens, there is no foul odor, and a certain amount of humus is produced, the straw composting is considered complete. Specifically, the testing items are as follows:

[0066] 1. Detect the highest temperature and duration of straw after adding straw composting agent, and record the above test results in Table 2;

[0067] 2. Detect the weight of straw before and 50 days after decomposition, calculate the weight loss rate of straw after 50 days of decomposition, and record the above test results in Table 2;

[0068] 3. After the straw has been composted with straw composting agent for 50 days, it is returned to the field. The growth of pests, diseases and weeds is observed to detect the pest and weed rate. The test results are recorded in Table 2.

[0069] Table 2 Summary of Performance Test Results of Straw Composting Agents in Examples 1-3

[0070]

[0071]

[0072] As shown in Table 2, without the addition of straw composting agent, the highest temperature of the straw could only reach 45℃ and the duration was short. After adding the straw composting agent provided in this application, the highest temperature could reach above 50℃ and the duration was longer (more than 8 days). In particular, with the addition of the straw composting agent provided in Example 1, the highest temperature could reach 70℃ and the duration was as long as 10 days. Without the addition of straw composting agent, the straw's weight loss rate due to its own degradation could only reach 20%. After adding the straw composting agent provided in this application, the straw weight loss rate could reach above 57%. Without the addition of straw composting agent, the pest and weed rate after straw return to the field was 10.5%. After adding the straw composting agent provided in this application, the pest and weed rate after straw return to the field was below 0.3%. This demonstrates that the straw composting agent provided in this application can achieve rapid heating and maintain a high temperature for a long time during the straw composting process; at the same time, the straw composting agent provided in this application has a good composting and degradation effect on straw, and no pests, diseases or weeds will occur when the composted and degraded straw is returned to the field.

[0073] Comparative Example 1

[0074] Based on Example 1, the difference between this comparative example and Example 1 is that: this comparative example does not add nitrite oxidizing bacteria raw powder; specifically: 15 kg of Staphylococcus xylose raw powder and 15 kg of Protozoa chrysospora raw powder are mixed evenly to obtain compound functional microbial agent raw powder; then 5.2 kg of corn straw, 30 kg of compound functional microbial agent raw powder, 5.2 kg of nitrification inhibitor and 5.2 kg of EM bacteria are mixed evenly to obtain straw composting agent.

[0075] Comparative Example 2

[0076] Based on Example 1, the difference between this comparative example and Example 1 is that: no *Plasmodium chrysosporium* powder was added in this comparative example; specifically: 15 kg of *Staphylococcus xylose* powder and 1 kg of nitrite-oxidizing bacteria powder were mixed evenly to obtain a compound functional microbial agent powder; then 5.2 kg of corn straw, 16 kg of compound functional microbial agent powder, 5.2 kg of nitrification inhibitor and 5.2 kg of EM bacteria were mixed evenly to obtain a straw composting agent.

[0077] Comparative Example 3

[0078] Based on Example 1, the difference between this comparative example and Example 1 is that: no Staphylococcus aureus raw powder was added in this comparative example; specifically: 15 kg of Phanerochaete chrysosporium raw powder and 1 kg of nitrite oxidizing bacteria raw powder were mixed evenly to obtain compound functional microbial agent raw powder; then 5.2 kg of corn straw, 16 kg of compound functional microbial agent raw powder, 5.2 kg of nitrification inhibitor and 5.2 kg of EM bacteria were mixed evenly to obtain straw composting agent.

[0079] Comparative Example 4

[0080] Based on Example 1, the difference between this comparative example and Example 1 is that: no Staphylococcus aureus powder or Protozoa chrysospora powder was added in this comparative example; specifically: 5.2 kg of corn stalks, 1 kg of nitrite oxidizing bacteria powder, 5.2 kg of nitrification inhibitor and 5.2 kg of EM bacteria were mixed evenly to prepare a straw composting agent.

[0081] Comparative Example 5

[0082] Based on Example 1, the difference between this comparative example and Example 1 is that: no Staphylococcus aureus powder or nitrite oxidizing bacteria powder was added in this comparative example; specifically: 5.2 kg of corn stalks, 15 kg of Phanerochaete chrysosporium powder, 5.2 kg of nitrification inhibitor and 5.2 kg of EM bacteria were mixed evenly to prepare a straw composting agent.

[0083] Comparative Example 6

[0084] Based on Example 1, the difference between this comparative example and Example 1 is that: no nitrification inhibitors and EM bacteria were added in this comparative example; specifically: first, 15 kg of Staphylococcus xylostella raw powder, 15 kg of Phanerochaete chrysospora raw powder, and 1 kg of nitrite oxidizing bacteria raw powder were mixed evenly to obtain a compound functional microbial agent raw powder; then, 5.2 kg of corn straw and 31 kg of compound functional microbial agent raw powder were mixed evenly to obtain a straw composting agent.

[0085] Comparative Example 7

[0086] Based on Example 1, the difference between this comparative example and Example 1 is that no compound functional microbial inoculant powder was added in this comparative example; specifically, 5.2 kg of corn stalks, 5.2 kg of nitrification inhibitor and 5.2 kg of EM bacteria were taken and mixed evenly to prepare a straw composting agent.

[0087] Comparative Example 8

[0088] Based on Example 1, the difference between this comparative example and Example 1 is that the raw powders of Staphylococcus xylostella, Phanerochaete chrysosporium, and nitrite-oxidizing bacteria used were not carbon-loaded. The bacterial solution obtained in step S1 of culture example 1 was dried at room temperature and then pulverized into fine powder to obtain unloaded functional microbial inoculum raw powders: unloaded Staphylococcus xylostella raw powder, unloaded Phanerochaete chrysosporium raw powder, and unloaded nitrite-oxidizing bacteria raw powder.

[0089] Experimental testing

[0090] A test field (4m*5m) was selected. 10.0kg of wheat straw was crushed into 5cm pieces and evenly spread in the field. The straw composting agent provided in Comparative Examples 1-8 was evenly spread on the prepared field at a dosage of 2kg per acre. The field was turned over to ensure even mixing of the straw and the composting agent. The initial moisture content of the fermentation material was controlled between 55% and 65% to promote microbial growth and prevent anaerobic fermentation caused by excessive moisture. This was used to test the performance of the straw composting agents provided in Comparative Examples 1-8. During this period, the pH value of the fermentation material was monitored and adjusted to 6.5-7.5 (if necessary, appropriate amounts of lime or potassium dihydrogen phosphate were added as regulators). The pile was turned over every 3 days to promote oxygen entry into the pile and accelerate microbial activity. After a period of fermentation, when the pile temperature gradually decreased, the color darkened, there was no foul odor, and a certain amount of humus was produced, the straw composting was considered complete. Specific testing items are as follows:

[0091] 1. Detect the highest temperature and duration of straw after adding straw composting agent, and record the above test results in Table 3;

[0092] 2. Detect the weight of straw before and 50 days after decomposition, calculate the weight loss rate of straw after 50 days of decomposition, and record the above test results in Table 3;

[0093] 3. Return the straw that has been composted with straw composting agent for 50 days to the field, observe the growth of pests, diseases and weeds, and use this to detect the pest and weed damage rate. Record the above test results in Table 3.

[0094] 4. Straw that has been composted with straw composting agent for 50 days was returned to the field. The organic carbon content in the soil (0-20cm soil layer) was tested to evaluate the carbon sequestration effect of straw return to the field. The test results were recorded in Table 4.

[0095] 5. After the straw has been composted for 50 days with straw composting agent, it was returned to the field. The contents of organic matter, available phosphorus, and available potassium in the soil were tested according to "Bio-organic Fertilizer (NY884-2012)" to evaluate the soil stabilization effect of straw composting agent applied to the field. The test results were recorded in Table 5.

[0096] Table 3 Summary of performance test results of straw composting agents for comparative examples 1-8

[0097]

[0098] As shown in Table 3, the performance of the straw composting agents provided in Comparative Examples 1-8 was inferior to that of Example 1. Compared with the blank control group, the maximum temperature of Example 1 increased by 25°C, the duration of the temperature was extended by 7 days, the weight loss rate after composting increased by 42%, and the rate of pests, diseases, and weeds decreased by 10.2%.

[0099] Compared to Example 1, the straw composting agents provided by Comparative Examples 1 to 3, which added two strains, were all inferior in performance. For Comparative Examples 1 to 3, the maximum temperatures were 66℃, 64℃, and 58℃, respectively, with temperature durations of 8 days, 7 days, and 7 days, respectively. The weight loss rates after composting were 60%, 57%, and 44%, respectively, and the rates of pests, diseases, and weeds were 1.3%, 1.8%, and 4.8%, respectively. The straw composting agents provided by Comparative Example 4, which only added nitrite-oxidizing bacteria powder, and Comparative Example 5, which added *Procambarus chrysospora* powder, were both inferior in performance to Example 1. The maximum temperatures for Comparative Examples 4 and 5 were 49℃ and 55℃, respectively, with temperature durations of 4 days and 5 days, respectively. The weight loss rates after composting were 25% and 28%, respectively, and the rates of pests, diseases, and weeds were 6.1% and 5.3%, respectively. Comparative Example 6, without the addition of nitrification inhibitors and EM bacteria, had a maximum temperature of 50°C for 5 days. After composting, the weight loss rate was 22%, and the rate of pests, diseases, and weeds was 8.7%. Compared to Example 1, the maximum temperature decreased by 20°C, the duration of the temperature was shortened by 5 days, the weight loss rate decreased by 40%, and the rate of pests, diseases, and weeds increased by 8.4%. Comparative Example 7, without the addition of compound functional microbial inoculant powder, had a maximum temperature of 48°C for 3 days. After composting, the weight loss rate was 19%, and the rate of pests, diseases, and weeds was 7.8%. Compared to Example 1, the maximum temperature decreased by 22°C, the duration of the temperature was shortened by 7 days, the weight loss rate decreased by 43%, and the rate of pests, diseases, and weeds increased by 7.5%. Comparative Example 8, with the addition of functional microbial inoculant powder without carbon loading, had a maximum temperature decreased by 2°C, the duration of the temperature was shortened by 1 day, the weight loss rate decreased by 1%, and the rate of pests, diseases, and weeds increased by 0.7%.

[0100] In Comparative Examples 1 to 5, the maximum temperature showed a significant downward trend as the number of strains decreased. Simultaneously, the gradual increase in the incidence of pests, diseases, and weeds indicates that the synergistic effect of multiple strains has a positive effect on inhibiting the growth of harmful organisms. In particular, Comparative Examples 4 and 5 showed the highest incidence of pests, diseases, and weeds, further illustrating that adding only two strains or a single strain of composting agent has a more limited effect on increasing the compost pile temperature and promoting straw decomposition compared to a composting agent with three strains. Compound functional microbial inoculant powder is an indispensable key component in the straw composting process. It not only effectively increases the compost pile temperature, prolongs the duration of high temperatures, and promotes rapid decomposition and composting of straw, but also effectively inhibits the survival of pathogens, pests, and weed seeds through its rich microbial community and synergistic mechanism. The absence of EM bacteria in Comparative Example 6 directly reduced the diversity of the microbial community in the compost pile. This directly resulted in a compost environment unfavorable to the growth of beneficial microorganisms, thus failing to effectively inhibit the survival of pathogens, pests, and weed seeds. Furthermore, due to the reduced diversity of the microbial community, the heat generated during its reproduction process also decreased accordingly, resulting in the fermentation material temperature in Comparative Example 6 not rising as significantly. Specifically, in Example 1, when the highest temperature reached 70°C and was maintained for 10 days, this treatment group showed a significant performance advantage compared to other treatment groups, indicating a synergistic heating effect among the three microbial strains and a longer duration of high temperature. Under these conditions, the straw decomposed extremely quickly, with a particularly significant composting effect. In addition, the incidence of pests, diseases, and weeds in Example 1 was only 0.3%, a figure far lower than other treatment groups, further demonstrating that this composting agent can not only efficiently promote the decomposition of straw but also effectively inhibit the occurrence of pests, diseases, and weeds.

[0101] Table 4 Summary of the carbon sequestration effect of straw composting agents applied during straw return to the field

[0102] test <![CDATA[Organic carbon storage (t·hm -2 )]]> Increase Blank control 14.5±0.26c - Example 1 22.2±0.55a 53.10％ Comparative Example 1 20.7±0.13a 42.76％ Comparative Example 2 21.1±0.06a 45.52％ Comparative Example 3 21.3±0.66a 46.90％ Comparative Example 4 20.0±0.24a 37.93％ Comparative Example 5 19.8±0.06a 36.55％ Comparative Example 6 19.1±0.36ab 31.72％ Comparative Example 7 17.2±0.20bc 18.62％ Comparative Example 8 17.5±0.13b 20.69％

[0103] Soil carbon sequestration is mainly achieved by reducing soil carbon pool decomposition and increasing soil carbon pool input. In the 0-20 cm soil layer, the average organic carbon storage in each treatment group increased by 18.62%-53.10% compared to the control, with Example 1 showing a particularly significant increase. Notably, Comparative Examples 7 and 8 were not loaded with biochar, and their organic carbon storage was only 17.2 t·hm². -2 17.5 t·hm -2，Compared to Example 1, the average soil organic carbon storage decreased by 34.48% and 32.41%. Example 1 has an advantage in increasing the organic carbon storage in the topsoil. The porosity and large specific surface area of ​​biochar can adsorb soil organic carbon, isolating microorganisms and their extracellular enzymes from this organic carbon and slowing down its decomposition. Returned straw enters the paddy field as exogenous carbon, and after decomposition and utilization by soil microorganisms, some of it is fixed in the soil carbon pool as organic matter components of soil aggregates and microbial biomass carbon. In particular, in Comparative Example 6, no nitrification inhibitor was added, and the organic carbon storage was only 31.72 t·hm². -2 Compared to Example 1, the average soil organic carbon storage decreased by 20.38%. Nitrification inhibitors indirectly promote carbon sequestration by slowing down the nitrification process and reducing N2O emissions; while nitrifying bacteria indirectly affect carbon sequestration by participating in the nitrification process and influencing soil nitrogen cycling, improving plant nitrogen absorption and utilization.

[0104] Table 5 Summary of Experiments on the Effect of Applying Straw Composting Agent to Improve Soil Consolidation Capacity When Returning Straw to the Field

[0105] test Organic matter (g / kg) Available phosphorus (mg / kg) Available potassium (mg / kg) Blank control 23.6 31.65 164.86 Example 1 27.9 36.12 205.97 Comparative Example 1 24.6 33.36 182.97 Comparative Example 2 26.3 35.24 194.07 Comparative Example 3 25.1 34.08 185.19 Comparative Example 4 24.3 33.12 179.99 Comparative Example 5 24.1 32.89 175.49 Comparative Example 6 25.8 35.32 199.98 Comparative Example 7 23.8 31.32 165.73 Comparative Example 8 26.5 35.61 200.31

[0106] As shown in Table 5, the soil stabilization effect of the straw composting agents provided in Comparative Examples 1-8 was not as good as that in Example 1. The soil stabilization effect of the straw composting agents gradually weakened with the decrease in the number of bacterial strains. Compared to Example 1, the contents of organic matter, available phosphorus, and available potassium in Comparative Example 7 decreased by 4.1 g / kg, 4.8 mg / kg, and 40.24 mg / kg, respectively, indicating that the addition of functional compound microorganisms is beneficial to improving soil stabilization.

[0107] Compared to the blank control group, the straw composting agent in Example 1 increased the content of soil organic matter, available phosphorus, and available potassium by 18.22%, 14.12%, and 24.93%, respectively. The experiment shows that the straw composting agent prepared in Example 1 helps to better decompose straw and improve soil nutrient content.

Claims

1. A straw decomposing agent, characterized by comprising: a microorganism; and a carrier for the microorganism. By weight, it comprises the following components: corn straw 10-20 parts, composite functional microbial inoculant 50-60 parts, nitrification inhibitor 10-20 parts, EM bacteria 10-20 parts; The composite functional microbial inoculant is composed of the following single functional microbial inoculant by weight: Staphylococcus xylosus XW-4 20-30 parts, Phanerochaete chrysosporium CGMCC 5.0776 20-30 parts, and nitrite oxidizing bacteria CCTCC NO: M2014203 1-5 parts; The preparation method of the functional microbial inoculant comprises the following steps: S1, inoculate the functional microbial inoculant into the composite culture medium, activate and culture for 24-48h, so that the strain reaches the logarithmic growth phase, and store the bacterial liquid; S2, mix the bacterial liquid obtained in step S1 with biochar, oscillate and adsorb, pass through a 200-mesh screen, wash, dry, and crush to obtain the functional microbial inoculant.

2. The straw decomposing agent according to claim 1, characterized in that, In step S1, the activation temperature of Staphylococcus xylosus is 25-30℃, the activation temperature of Phanerochaete chrysosporium is 28-32℃, and the activation temperature of nitrite oxidizing bacteria is 30-35℃; and / or in step S2, the biochar is nitrogen and phosphorus loaded biochar.

3. The straw decomposing agent according to claim 1, characterized in that, In step S2, the oscillation and adsorption conditions are: constant temperature oscillation and adsorption at 25-35℃ and 160-220r / min for 24-48h.

4. The straw decomposing agent according to claim 1, characterized in that, In step S2, the conditions for obtaining biochar by calcining corn straw are: pyrolysis at 600℃ for 1h.

5. The straw decomposing agent according to claim 1, characterized in that, In step S1, the composition of the composite culture medium per liter is: 250-300g glucose, 150-200g soybean meal powder, 100-120g magnesium sulfate, 10-20g corn straw powder, 30-50g potassium dihydrogen phosphate, 8-10g vitamin B1, and the balance is water, and the pH of the composite culture medium is 7.

0.

6. The straw decomposing agent according to claim 5, characterized in that, The particle size of the corn straw powder is passed through a 60-100-mesh screen.

7. The straw decomposing agent according to claim 1, characterized in that, The nitrification inhibitor is selected from any one of nitrogen pyridine, dicyandiamide, and 3,4-dimethylpyrazole phosphate.

8. The straw decomposing agent according to claim 1, characterized in that, The length of the corn straw is 3-5cm.

9. The straw decomposing agent according to claim 2, characterized in that, The preparation method of the biochar is: first, obtain biochar by calcining corn straw, then add the biochar into a mixed solution containing urea and diammonium hydrogen phosphate, ultrasonic treatment for 2h, dry, take the solid powder, pyrolysis at 600℃ for 30min to obtain nitrogen and phosphorus loaded biochar.

10. The straw decomposing agent according to claim 9, characterized in that, The mass ratio of urea, diammonium hydrogen phosphate, and biochar is 2-3:4-5:

10.

11. The straw decomposing agent according to claim 2, characterized in that, The bacterial liquid and biochar are mixed in a ratio of 10-15mL:1g.

12. The application of the straw decomposition agent of any one of claims 1-11 in straw in-situ return, carbon sequestration, and improving soil nutrients, wherein the soil nutrients refer to one or more of organic matter, available phosphorus, and available potassium.

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