Method for preparing biological carbon fertilizer by quickly decomposing agricultural straws and returning biological carbon fertilizer to field nearby and application of biological carbon fertilizer

Abstract

The invention belongs to the field of biological carbon fertilizers, and provides a method for preparing a biological carbon fertilizer from agricultural straws through rapid decomposition and returning the biological carbon fertilizer to the field nearby, which comprises the following steps: a, crushing the agricultural straws into crushed materials with the length of not more than 3mm; b, adding water which is 2-3 times of the weight of the crushed material and a composite oxidative degradation agent which accounts for 2-3% of the dry weight of the crushed material into the crushed material, and stirring and mixing for 15-20 minutes to obtain a semi-finished product of the biological carbon fertilizer; and c, directly returning the semi-finished product of the biological carbon fertilizer to the field or storing and decomposing. According to the invention, the agricultural straws can be quickly decomposed and cured, and the treated biological carbon fertilizer contains more than 70% of organic matters and more than 5% of humic acid; and bacteria and insect pests in the straws are killed, the carbon source of the soil is increased, the structure of the soil is improved, and the water and fertilizer retention capability of the soil is enhanced.

Description

Technical Field

[0001] This invention relates to the field of agricultural waste resource utilization and fertilizer technology, specifically to a method and application for rapidly decomposing agricultural straw into high-organic-matter bio-carbon fertilizer in the field and returning it to the field nearby. Background Technology

[0002] my country has a vast arable land area, but the soil organic matter content is generally low and showing a downward trend. Returning straw to the field is an important measure to replenish soil organic matter, but traditional direct straw return methods have many drawbacks: 1) The amount of straw returned to the field is limited, and a large amount of straw cannot be disposed of; the amount of straw returned to the field is not appropriate, with an annual straw production of about 1,000 kg per mu, while the amount of straw returned to the field should not exceed 300 kg per mu.

[0003] 2) Returning untreated straw directly to the field exacerbates pests and diseases in the next crop due to the insect eggs and pathogens it carries.

[0004] 3) The straw returned to the field is large and fluffy, making it difficult for the roots of the next crop to penetrate deep into the soil, thus making the crop prone to lodging.

[0005] 4) Crop roots have difficulty obtaining nutrients from the soil.

[0006] 5) The decomposition of straw requires the consumption of oxygen and water, which leads to a conflict between straw and crop roots in the process of competing for oxygen and water.

[0007] Although there are various straw composting methods in the existing technology, they are usually time-consuming (several months to a year), have complex processes, require large sites and turning equipment, and are difficult to achieve rapid field processing and large-scale promotion and application.

[0008] A search revealed that CN109534862A discloses a method for returning straw to the field in situ, including the following steps: first, crushing the straw and spreading it evenly on the soil surface; second, uniformly sprinkling dilute acid on the straw; third, uniformly sprinkling quicklime and water on the straw with the diluted acid; and fourth, spreading straw composting microbial inoculant on the straw surface, then tilling the land to incorporate the straw into the soil. This method uses substances such as acid that are unfriendly to the soil, is overly complex, and produces fertilizer with low organic matter content.

[0009] Therefore, it is urgent to develop a straw treatment technology that is efficient, fast, low-cost, has a high organic matter content in fertilizer, and can be operated on-site. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides a simple, short-cycle, and low-cost method for the rapid composting of agricultural straw, which can quickly convert straw into high-value-added bio-carbon fertilizer in the field, achieving efficient resource utilization of straw and rapid improvement of soil quality.

[0011] In response to the problems associated with returning straw to the field, this invention proposes a scheme of "collecting and crushing straw at the field edge, oxidizing and degrading lignin at the field edge, adding microbial inoculants, and returning straw to the field for fertilization nearby," which transforms straw into bio-carbon fertilizer and directly returns it to the field.

[0012] The technical solution of this invention is: A method for rapidly composting agricultural straw into bio-carbon fertilizer for local application to the field includes the following steps: a. Crush agricultural straw into a powder with a length not exceeding 3mm; b. Add 2-3 times its weight of water and 2%-3% of the dry weight of the pulverized material to the pulverized material, and stir for 15-20 minutes to obtain a semi-finished bio-carbon fertilizer; the composite oxidizing and degrading agent is K2CO3·(CaCO3). 0.5 ·(MgCO3) 0.5 ·3H2O2; c. The semi-finished bio-carbon fertilizer is directly returned to the field or stored for composting.

[0013] Preferably, the composite oxidative degradation agent is prepared by a method comprising the following steps: mixing K2CO3, CaCO3, and MgCO3 in a molar ratio of 1:0.5:0.5; adding hydrogen peroxide solution containing 5A molecular sieve dropwise under cooling and stirring conditions; controlling the reaction temperature at 20℃~30℃ for 30~40 minutes; then allowing it to stand for 60~80 minutes to obtain a reaction semi-finished product; and dehydrating and drying the reaction semi-finished product to obtain the composite oxidative degradation agent, wherein the amount of 5A molecular sieve is 0.2%~0.5% of the weight of K2CO3.

[0014] Preferably, in step b, 0.002% to 0.003% of a biological composting agent based on the dry weight of the crushed material can be added to the semi-finished bio-carbon fertilizer, and stirring can continue for 15 to 20 minutes. Adding the biological composting agent can further promote the rapid increase of microorganisms and improve the final viable count of the product. However, bio-carbon fertilizer meeting national standards can still be achieved without adding the biological composting agent.

[0015] Preferably, the biological decomposition-promoting agent is Xiangnong 502, provided by the Hunan Provincial Institute of Cultivated Land and Agricultural Environment Ecology; it can also be a biological agent disclosed in the prior art that can be used to treat crop straw, such as a biological agent for treating crop straw disclosed in CN107099490B.

[0016] Preferably, the bio-carbon fertilizer semi-finished product is decomposed into a finished product within 7 to 15 days.

[0017] Preferably, the agricultural straw includes agricultural straw rich in plant fiber, such as corn straw and rice straw.

[0018] The present invention also provides a bio-carbon fertilizer prepared by the above method, the physicochemical indicators of which are: pH ≥ 6, humidity about 50%, electrical conductivity less than 50 μS / cm, organic matter content > 70%, humic acid content ≥ 5%, and effective viable bacteria count > 121 million / gram.

[0019] This invention also provides the application of the biocarbon fertilizer in improving soil, increasing soil organic matter content, and promoting crop growth.

[0020] This invention proposes a composite oxidative degrading agent that can degrade lignin in straw under normal temperature and pressure conditions, thereby releasing substances such as cellulose and hemicellulose, which is beneficial for the rapid decomposition and maturation of straw. The inventors have creatively combined K₂CO₃ (potassium carbonate), CaCO₃ (calcium carbonate), and MgCO₃ (magnesium carbonate) through a specific process to obtain a synergistic product that combines fertilizer properties with strong oxidizing power. This product is specifically designed to break down the stubborn lignin structure in straw, converting lignin into water-soluble organic matter, thereby increasing the organic matter content of the soil. This composite oxidative degrading agent can rapidly degrade straw lignin under normal temperature and pressure, achieving rapid straw decomposition in the field. Our carbonates are mainly K, Ca, and Mg, which are components of fertilizers, and do not contain sodium salts, thus not causing soil salinization.

[0021] The preparation method of this invention uses 5A molecular sieve as a stabilizer and catalyst. During the hydrogen peroxide addition reaction, the molecular sieve can adsorb moisture and impurities, improve the stability of the final product, and prevent hydrogen peroxide from decomposing too quickly during the preparation process.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) High efficiency and speed: This invention uses a composite oxidative degradation agent to quickly break down the lignin structure at room temperature and pressure, shortening the traditional composting cycle of several months to 7-15 days, thus achieving rapid decomposition of straw.

[0023] 2) Excellent fertilizer effect: The bio-carbon fertilizer obtained by this invention has an organic matter content of over 70%, a humic acid content of ≥5%, and is rich in beneficial bacteria, which can significantly improve soil fertility, improve soil aggregate structure, and enhance water and fertilizer retention capacity.

[0024] 3) Thorough harmlessness: The process of this invention can effectively kill pathogens and insect eggs carried in straw (such as fecal coliform count, ascarid egg mortality rate, etc. all meet the standards), solving the problem of pest and disease transmission when directly returned to the field.

[0025] 4) Simple operation and low cost: The entire process can be completed in the field without the need for complex equipment and large sites, realizing the "removal of straw from the field but not from the land", and returning it to the field nearby after treatment, which greatly reduces transportation and application costs.

[0026] 5) Increased yield and improved quality: The embodiments of the present invention show that the application of the bio-carbon fertilizer of the present invention can significantly extend the crop growth cycle and improve crop yield and fruit quality.

[0027] The detailed structure of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0028] Figure 1 The process flow diagram of the method for rapidly composting agricultural straw into bio-carbon fertilizer and returning it to the field is shown in the present invention. Figure 2 This is a fertilizer organic matter test report according to an embodiment of the present invention; Figure 3 This is a test report on fertilizer microorganisms and other indicators in embodiments of the present invention; Figure 4 This is a test report on indicators such as humic acid content in fertilizers according to embodiments of the present invention; Figure 5 This is the second test report on indicators such as fertilizer humic acid content in an embodiment of the present invention. Figure 6 This is the second test report on fertilizer microorganisms and other indicators in this embodiment of the invention; Figure 7 These are photos of tomatoes at different stages in the control area of ​​Example 4. Figure 7 a is a photo of tomatoes in the control area at an early stage. Figure 7 b is a mid-stage photograph of tomatoes in the control area. Figure 7 c is a post-processed photo of tomatoes in the control area. Figure 7 d is a late-stage photograph of tomatoes in the control area; Figure 8 These are photos of tomatoes at different stages in the experimental area of ​​Example 4. Figure 8 a is an early photo of tomatoes in the experimental area. Figure 8 b is a mid-term photo of tomatoes in the experimental area. Figure 8 c is a later-stage photo of tomatoes from the experimental area. Figure 8 d is a late-stage photograph of tomatoes in the experimental area; Figure 9 These are photos of longan trees at different stages of fruiting, as shown in Example 5. Figure 9 Photo 'a' shows the initial fruiting stage. Figure 9 b is a photo of the fruit set at mid-stage. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0030] Equipment used in this invention: Crusher: Model 20B manufactured by Henan Hengchang Environmental Protection Machinery Co., Ltd. Mixer: Self-designed and manufactured. National patent application number: 2025 217715749 Reactor: SUS316L manufactured by Shandong Laizhou Shenglong Machinery Co., Ltd. Centrifugal Dryer: Changzhou Longtai Drying Technology Co., Ltd. LPG-100 model The biological probiotic used in this invention is Xiangnong 502, which was provided by the Hunan Provincial Institute of Cultivated Land and Agricultural Environment Ecology.

[0031] Please refer to the test report for the detection method used in this invention. Example 1

[0032] The composite oxidative degradation agent provided by this invention is prepared as follows: Reaction formula:

[0033] Raw materials: K2CO3 purity 98%; CaCO3 purity 96%; MgCO3 purity 99%; H2O2 purity 50%; 5A molecular sieve.

[0034] K2CO3, CaCO3, MgCO3, and H2O2 are all measured in molar amounts.

[0035] The specific operating steps of the composite oxidative degradation agent are as follows: First, dissolve 5A molecular sieve in hydrogen peroxide, using 0.2% of the weight of K2CO3. Second, K2CO3, CaCO3, and MgCO3 are weighed and added into a reaction vessel equipped with a cooling system and a stirring device in a molar ratio. Third, slowly drip hydrogen peroxide containing dissolved 5A molecular sieve into the reactor, start the cooling system and stirring device, control the reaction temperature at about 25°C, react for 30 minutes, and then let it stand for 60 minutes to obtain the reaction semi-finished product. Fourth, the reactants are dehydrated and dried using a centrifugal dryer to obtain a composite oxidative degradation agent.

[0036] Product characteristics: The composite oxidative degradation agent has the following appearance: white powder, non-toxic, and slightly salty.

[0037] Relative molecular weight: 332.45.

[0038] Surface density: γ≈2.1303 g / cm³ 3 Theoretical reactive oxygen species: 14.438% The obtained semi-finished product is dehydrated and dried using a centrifugal dryer to obtain a composite oxidizing and degrading agent.

[0039] A method for rapidly composting agricultural straw into bio-carbon fertilizer for local application to the field includes the following steps: First, collect agricultural straw away from the field (in this example, corn straw); Second, use a shredder to shred the straw at the edge of the field to make shredded material with a length of no more than 3 mm; Third, put the crushed material into a mixer, add water three times the weight of the crushed material, and then add 3% of the above-prepared composite oxidizing and degrading agent equivalent to the crushed material. Stir for 20 minutes to prepare a semi-finished bio-carbon fertilizer. This semi-finished bio-carbon fertilizer can be directly returned to the field for fertilization or packaged and stored in a metered manner. It will be basically decomposed into a finished product after seven days. Fourth, the bio-carbon fertilizer produced is brownish-brown in appearance, odorless, loose in texture, with a pH ≥ 6, a moisture content of about 50%, a salt content of less than 50 μs / cm, an organic matter content of > 70%, a humic acid content of ≥ 5%, and an effective live bacteria count of > 121 million / gram.

[0040] Three samples of the bio-carbon fertilizer prepared in Example 1 were taken and sent to relevant testing units for testing in the name of the applicant's company (Beijing Tongqu Agricultural and Animal Husbandry Technology Co., Ltd.): A report from the Beijing Academy of Science and Technology's Institute of Analysis and Testing shows (see...) Figure 2 (and Table 1): Organic matter content is as high as 897 g / kg (89.7%), pH value is 6.13, and water content is 51.9%.

[0041] Table 1. Organic Fertilizer Sample Test Data Report

[0042] The bio-carbon fertilizer sample 2 prepared by the method in Example 1 was tested for microorganisms, colonies, etc. The test report from the Agricultural Chemical Testing Center of Hunan Academy of Agricultural Sciences showed (see...). Figure 3 (and Table 2): pH 6.86, fecal coliform count <3, and ascarid egg mortality rate ≥100% are all qualified. The effective viable bacteria count (Bacillus subtilis) reaches 121 million / g, which is far greater than the industry standard.

[0043] Table 2. Test Report from the Agrochemical Testing Center of Hunan Academy of Agricultural Sciences

[0044] In addition, sample 3 of the bio-carbon fertilizer prepared by the method in Example 1 was sent for testing of humic acid content. The test report from Heilongjiang Huace Testing Technology Co., Ltd. showed that the humic acid content was as high as 16.06% (see...). Figure 4 (and Table 3) Table 3 Test Report from Heilongjiang Huace Testing Technology Co., Ltd.

[0045] The above data fully demonstrate that the bio-carbon fertilizer prepared by the method of the present invention has high quality and excellent agricultural value.

[0046] Example 2 Preparation of composite oxidative degradation agent Raw materials: K2CO3 with a purity of 98%, CaCO3 with a purity of 96%, MgCO3 with a purity of 99%, H2O2 with a purity of 50%, and 5A molecular sieve.

[0047] Weigh out 1 mol of K₂CO₃, 0.5 mol of CaCO₃, and 0.5 mol of MgCO₃ by molar ratio and add them to a SUS316L reactor. Dissolve 0.3% (by weight of K₂CO₃) of 5A molecular sieve in sufficient 50% H₂O₂ (ensuring complete reaction with the carbonate). Under stirring and cooling conditions, slowly add hydrogen peroxide solution dropwise to the reactor, control the temperature at approximately 22°C, react for 40 minutes, and let stand for 50 minutes. Dehydrate and dry the resulting material using an LPG-100 centrifugal dryer to obtain a white powdery composite oxidizing degradative agent.

[0048] Preparation of biochar fertilizer: In a certain area of ​​Guangdong, corn stalks were crushed to below 3mm. 1000kg of the crushed stalks were taken and put into a mixer, along with 2500kg of water and 25kg of the prepared compound oxidizing degradation agent, and stirred for 18 minutes. Then, 20g of Xiangnong 502 biological decomposition-promoting bacteria were added, and stirring continued for 20 minutes to obtain a semi-finished bio-carbon fertilizer. This semi-finished bio-carbon fertilizer matured into a finished product within 7 days.

[0049] Three samples of the biochar fertilizer prepared in Example 2 were taken and sent to relevant testing units for testing: The results showed that the organic matter content was as high as 807 g / kg (80.7%) and the electrical conductivity was 44.4 μS / cm.

[0050] Table 4 Organic Fertilizer Sample Test Data Report

[0051] The test report from Heilongjiang Huace Testing Technology Co., Ltd., for the bio-carbon fertilizer sample 2 prepared in Example 2, showed that the humic acid content was 8.15% (see Table 5 and 2). Figure 5 ).

[0052] Table 5 Humic Acid Detection Data

[0053] The microbial content of biochar fertilizer sample 3 prepared in Example 2 was detected (see Table 6 and ). Figure 6 The pH was 6.84, the fecal coliform count was <3, and the ascarid egg mortality rate was 100%, which met the national standards. The effective live bacteria count (Bacillus subtilis) was 135 million / g, which is far greater than the industry standard and significantly higher than the live bacteria count of the bio-carbon fertilizer prepared in Example 1.

[0054] Table 6 Microbial Detection Data

[0055] Example 3 The preparation method of the composite oxidative degradation agent is the same as in Example 1; Preparation of biochar fertilizer In a certain area of ​​Guangdong, corn stalks were crushed to below 3mm. 2000kg of the crushed stalks were taken and put into a mixer, along with 4900kg of water and 50kg of the composite oxidizing degradation agent prepared in Example 1, and stirred for 20 minutes. Then, 25g of Xiangnong 502 biological decomposition-promoting bacteria agent was added, and stirring continued for another 25 minutes to obtain a semi-finished bio-carbon fertilizer. This semi-finished bio-carbon fertilizer matured into a finished product within 8 days.

[0056] Three samples of the bio-carbon fertilizer prepared in Example 1 were taken and sent to relevant testing units for testing: Sample 1 of the bio-carbon fertilizer prepared in Example 3 was sent to a testing institution for testing: as shown in Table 7, the organic matter content was as high as 756 g / kg (75.6%), and the electrical conductivity was 45.1 μS / cm.

[0057] Table 7 Organic Fertilizer Sample Test Data Report

[0058] The humic acid content of sample 2 of the bio-carbon fertilizer prepared in Example 3 was found to be 5.48%, as shown in Table 8.

[0059] Table 8 Test Report from Heilongjiang Huace Testing Technology Co., Ltd.

[0060] The microbial content and other parameters of the bio-carbon fertilizer sample 3 prepared in Example 3 were tested and found to meet national standards.

[0061] Comparative Example 1 The preparation method was the same as in Example 1, but without the addition of the composite oxidizing degrading agent. The results showed that the crushed straw material only slightly changed color within the same time frame, remained hard, could not be fully decomposed, had an extremely low organic matter conversion rate, and still retained a noticeable plant fiber structure.

[0062] Comparative Example 2 The preparation method is the same as in Example 1, but the composite oxidative degradation agent of the present invention is replaced with acid and lime (prepared by referring to the method of Example CN109534862A in the background). The results showed that the straw crushed material did not change color much within the same time, had an odor, felt hard, had a low organic matter conversion rate, and still had obvious plant fiber structure.

[0063] Example 4 Tomato cultivation experiment Experimental design: 67 m² of soil (original organic matter 0.78%) was divided into two zones.

[0064] Control area: Applied with commercially available ordinary organic fertilizer (35% organic matter content). Photos of tomatoes at different stages in the control area are shown below. Figure 7 , Figure 7 a is a photo of tomatoes in the control area at an early stage. Figure 7 b is a mid-stage photograph of tomatoes in the control area. Figure 7 c is a post-processed photo of tomatoes in the control area. Figure 7 d is a late-stage photograph of tomatoes in the control area.

[0065] Experimental area: The bio-carbon fertilizer prepared in this embodiment (organic matter content >70%) was applied. Photos of tomatoes at different stages in the experimental area are shown below. Figure 8 , Figure 8 a is an early photo of tomatoes in the experimental area. Figure 8 b is a mid-term photo of tomatoes in the experimental area. Figure 8 c is a later-stage photo of tomatoes from the experimental area. Figure 8 Photo d shows a late-stage photograph of tomatoes in the experimental area.

[0066] 100 tomato seedlings will be planted in each area.

[0067] result: Soil improvement effect: One month after fertilization, the soil organic matter in the control area increased to 1.02%, and in the experimental area it increased to 4.3%.

[0068] Crop growth effect: Control area: The tomato growth cycle is 100 days. During the entire fruiting cycle, each plant produces 20-30 fruits, and the yield per plant is about 2.5 kg. Figure 7 d is a photo taken at 100 days, showing that the crop itself is about to wither and can no longer produce new fruit.

[0069] Experimental area: The tomato growth cycle is extended to 180 days, with 60-80 fruits per plant during the entire fruiting period, and a yield of about 5 kg per plant. Figure 8 Photo d is taken 180 days later, proving that our crops still bear fruit 180 days later, demonstrating a long fruiting cycle.

[0070] Experiments have shown that the bio-carbon fertilizer prepared by this invention has significant effects on improving soil and promoting crop yield.

[0071] Example 5 A longan cultivation experiment was conducted on a longan tree that had not borne fruit for many years. The bio-carbon fertilizer prepared in Example 1 was applied, and the experimental records are as follows: On August 19, 2024, in a factory in Maoming High-tech Zone, Guangdong Province, carbon fertilizer was applied to a longan tree that had been neglected for 7-8 years and had not borne fruit. On September 1, 2024, some leaves sprouted new leaves; by September 19, 2024, all the leaves had sprouted new leaves; by March 27, 2025, many new branches bearing fruit had grown; and by May 7, 2025, all the branches were covered with small longan fruits (see...). Figure 9 Experiments have shown that the bio-carbon fertilizer of this invention has a good effect on increasing the yield of longan.

[0072] The above description is a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for rapidly composting agricultural straw into bio-carbon fertilizer for local application to the field, characterized in that, Includes the following steps: a. Crush agricultural straw into a powder with a length not exceeding 3mm; b. Add 2-3 times its weight of water and 2%-3% of the dry weight of the pulverized material to the pulverized material, and stir for 15-20 minutes to obtain a semi-finished bio-carbon fertilizer; the composite oxidizing and degrading agent is K2CO3·(CaCO3). 0.5 ·(MgCO3) 0.5 ·3H2O2; c. The semi-finished bio-carbon fertilizer is directly returned to the field or stored for composting.

2. The method according to claim 1, characterized in that, The composite oxidative degradation agent is prepared by a method comprising the following steps: K₂CO₃, CaCO₃, and MgCO₃ in a molar ratio of 1:0.5:0.5 were mixed, and a hydrogen peroxide solution containing 5A molecular sieve was added dropwise under cooling and stirring conditions to carry out the reaction. The reaction temperature was controlled at 20℃~30℃ for 30~40 minutes, and then allowed to stand for 60~80 minutes to obtain a reaction semi-finished product. The reaction semi-finished product was dehydrated and dried to obtain a composite oxidative degradation agent, wherein the amount of 5A molecular sieve used was 0.2%~0.5% of the weight of K₂CO₃.

3. The method according to claim 1 or 2, characterized in that, In step b, 0.002% to 0.003% of a biological composting agent based on the dry weight of the crushed material can be added to the semi-finished biochar fertilizer, and stirring can be continued for 15 to 20 minutes.

4. The method according to claim 3, characterized in that, The biological composting agent is Xiangnong 502.

5. The method according to claim 1 or 2, characterized in that, The bio-carbon fertilizer semi-finished product is decomposed into a finished product within 7 to 15 days.

6. The method according to claim 1 or 2, characterized in that, The agricultural straw includes corn straw, rice straw, etc.

7. A biochar fertilizer prepared by the method according to any one of claims 1-6, characterized in that, Its physicochemical properties are: pH ≥ 6, humidity approximately 50%, electrical conductivity less than 50 μS / cm, organic matter content > 70%, humic acid content ≥ 5%, and effective viable bacteria count > 121 million / gram.

8. The application of the biocarbon fertilizer according to claim 7 in improving soil, increasing soil organic matter content, and promoting crop growth.

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