Method for promoting microbial balance and improving ecological function of soil by straw returning to field

Abstract

The invention discloses a method for promoting microbial balance and improving the ecological function of soil through straw returning, and relates to the technical field of agricultural soil improvement. In a raw material pretreatment link, microbial agents A and B are added and fixed in a biochar pore structure, and a good foundation is laid for subsequent field returning through operations of pyrolysis carbonization, biological enzyme addition, foliage spraying of a microbial activator and the like. During field returning operation, measures such as specific deep ploughing depth, straw covering thickness and soil improvement agent adding are adopted according to different soil characteristics. In the fertigation process, the relative water content of soil is accurately controlled, fertilization is conducted according to the specific nitrogen-phosphorus-potassium proportion, and drip irrigation and spray irrigation modes are combined. The change of soil microbial communities is monitored by a high-throughput sequencing technology every 15 days, and the soil oxidation-reduction potential is measured by an oxidation-reduction potential instrument and is regulated and controlled in time. The problem of traditional straw returning is effectively solved, and the soil ecological function and the crop yield are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural soil improvement, and specifically provides a method for returning straw to the field to promote microbial balance and enhance soil ecological functions. Background Art

[0002] In agricultural production, directly crushing straw and returning it to the field after crop harvest is the main current utilization method of straw. This single straw returning mode is easy to operate and can increase the content of soil organic matter to a certain extent.

[0003] However, China has a rich variety of soil types, and there are significant differences in environmental factors such as soil texture, pH, fertility level, and water content in different regions. For example, in acidic red soil areas, the content of active aluminum in the soil is relatively high, and the microbial activity is easily inhibited; in saline-alkali soil areas, the high-salt environment is not conducive to the growth of straw-decomposing microorganisms; in sandy soils, the water and fertilizer retention capacity is poor, and the decomposition rate of straw is fast after returning to the field but it is easy to cause nutrient loss. The single straw returning mode does not fully consider these soil environmental differences, resulting in many problems in actual production. In sticky soils, after straw is crushed and returned to the field, the soil aeration is easily deteriorated, affecting the root respiration of crops; in poor soils, the decomposition of straw is slow and it is difficult to effectively improve soil fertility; and due to not adapting to the survival needs of soil microorganisms, it may also cause an imbalance in the soil microbial community structure, reducing the stability and functions of the soil ecosystem, and preventing the full realization of the comprehensive benefits of straw returning to the field.

[0004] Traditional straw returning methods have many problems, such as slow straw decomposition, affecting the sowing and growth of the next crop; harmful microorganisms are easily bred during the straw returning process, causing soil-borne diseases; at the same time, due to the imbalance of the carbon-nitrogen ratio of straw, the soil microbial community structure is unreasonable, and the microbial activity is inhibited, and its improvement effect on the soil cannot be fully exerted.

[0005] Currently, although there are some improved technologies for straw returning to the field, the comprehensive benefits of straw returning to the field are still difficult to be fully realized. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for returning straw to the field to promote microbial balance and enhance soil ecological functions, so as to solve the problems of slow straw decomposition, easy breeding of harmful microorganisms, unreasonable soil microbial community structure, and inability to adapt to different soil environments existing in traditional straw returning methods.

[0007] To achieve the above purpose, the present invention provides the following technical solution: A method for returning straw to the field to promote microbial balance and enhance soil ecological functions, including.

[0008] 1. Raw material pretreatment: Harvest and collect crop straw as raw material. Take part of the straw and crush it. Add microbial inoculant A and microbial inoculant B to the straw and carry out pyrolytic carbonization to fix the microorganisms in the pore structure of biochar. Microbial inoculant A contains Bacillus subtilis and Trichoderma, and the mass ratio of Bacillus subtilis to Trichoderma is 2:1. The addition amount of microbial inoculant A is 0.1% of the weight of the raw material. Microbial inoculant B contains Bacillus and Pseudomonas, and the addition amount is 0.05% of the weight of the raw material. The pyrolysis temperature is controlled at 400 - 600 °C, the heating rate is 5 - 10 °C / min, and the pyrolysis time is 2 - 4 h. Crush the remaining straw to a length of 2 - 4 cm and mix it evenly with biochar. The mass ratio of biochar to straw is 1:4 - 6. Bioenzymes can be added to the mixture of straw and biochar. The bioenzymes include cellulase and ligninase. The addition amount of cellulase is 0.05% of the weight of the straw, and the addition amount of ligninase is 0.03% of the weight of the straw. Before harvesting the crop straw, a microbial activator can be sprayed on the leaf surface. The microbial activator contains various trace elements and amino acids, and the spraying concentration is 0.2%.

[0009] When microbial inoculants A and B are added during raw material pretreatment and fixed in the biochar pores through pyrolytic carbonization, it provides a stable living environment for the microorganisms. Beneficial microorganisms such as Bacillus subtilis, Trichoderma, Bacillus, and Pseudomonas can survive and reproduce better in the soil under the protection of biochar, increasing the quantity and variety of beneficial microorganisms in the soil, optimizing the soil microbial community structure, and enhancing the stability and function of the soil ecosystem. These beneficial microorganisms can participate in processes such as nutrient cycling and organic matter decomposition in the soil, providing a better soil environment for crop growth.

[0010] 2. Field return operation: Evenly spread the treated mixture of straw and biochar on the soil surface, and then carry out deep plowing with a depth of 18 - 22 cm. After deep plowing, rice straw can be covered on the soil surface with a thickness of 4 - 6 cm. A soil conditioner layer can also be set in the soil after field return. The soil conditioner is a mixture of biochar and zeolite, and the mass ratio of the two is 3:2, with an application rate of 150 kg per mu.

[0011] After pyrolyzing and carbonizing part of the straw and then mixing it with the remaining straw for returning to the field, biochar can not only adsorb and preserve nutrients, but also promote the decomposition of straw. Microorganisms are fixed inside the pores of biochar, making contact with the straw more sufficient, and can decompose components such as cellulose and lignin in the straw more efficiently. The mass ratio of biochar to straw of 1:4 - 6 ensures the maximization of the promoting effect of biochar on straw decomposition, accelerates the decomposition rate of straw in the soil after returning to the field, enables the nutrients in the straw to be released more quickly, and be absorbed and utilized by the soil and crops, reducing the impact on the sowing and growth of the next-season crops. During the operation of returning to the field, plow deeply by 18 - 22 cm to turn the straw and biochar mixture into the deep layer of the soil, breaking the plow sole layer of the soil, increasing the air permeability and water permeability of the soil. The straw and biochar can also promote the formation of soil aggregates in the soil, improve the soil structure, enhance the water-holding and fertilizer-holding capacity of the soil, create a good physical environment for the growth of crop roots, and be conducive to the growth and nutrient absorption of crop roots.

[0012] 3. Irrigation and fertilization: After returning to the field, use a soil moisture sensor for real-time monitoring, control the irrigation amount to keep the relative soil water content at 60% - 70%, and fertilize according to the ratio of nitrogen, phosphorus, and potassium of 3:1:2. Select urea for nitrogen fertilizer, superphosphate for phosphorus fertilizer, and potassium sulfate for potassium fertilizer. During the irrigation process, adopt a combination of drip irrigation and sprinkler irrigation.

[0013] 4. Monitoring and regulation: Use high-throughput sequencing technology to monitor the changes in soil microbial communities every 15 days, and at the same time use an oxidation-reduction potential meter to measure the soil oxidation-reduction potential. When the oxidation-reduction potential deviates from the range of -100 mV to 300 mV, adjust the soil oxidation-reduction potential by adjusting the irrigation amount or adding an oxidation-reduction regulator. When it is detected that the genus Bacillus in the soil is lower than 1×10 6 cfu / g and the genus Pseudomonas is lower than 5×10 5 cfu / g, top-dress the microbial agent B.

[0014] In the present invention, the in-situ generation of microorganisms on biochar has significant advantages compared with the prior art. The pore structure of biochar provides physical protection and a stable microenvironment for microorganisms, regulates the acidity, alkalinity, and oxidation-reduction potential, which is conducive to the survival and reproduction of microorganisms; microorganisms are in close contact with the straw and cooperate with the added bioenzymes to greatly improve the straw decomposition efficiency; a variety of beneficial microorganisms can better colonize in the soil with the help of biochar, optimize the microbial community structure, inhibit harmful microorganisms, and at the same time, the microbial metabolism and biochar interact with each other to promote the formation of soil aggregates, regulate the acidity and alkalinity, and improve the physical and chemical properties such as soil aeration, water retention, and fertilizer retention, creating an excellent soil environment for crop growth and effectively solving the problems of traditional straw returning to the field.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. The present invention provides a method for improving soil ecological function, which includes adding microbial inoculants A and B and fixing them in the pore structure of biochar, providing a suitable living environment for beneficial microorganisms, promoting the growth and reproduction of beneficial microorganisms, effectively adjusting the soil microbial community structure, and enhancing the stability of the soil ecosystem.

[0017] 2. The addition of bioenzymes in the present invention can accelerate the decomposition of cellulose and lignin in straw. The synergistic effect of microbial inoculants and microbial activators can also improve the activity of straw-decomposing microorganisms, accelerate the straw decomposition rate, and reduce the impact on the sowing and growth of the next crop.

[0018] 3. For different soil types, such as acidic red soil, saline-alkali soil, sandy soil, etc., the present invention can improve the soil environment, enhance the effect of straw returning to the field, strengthen the water and fertilizer retention capacity of the soil, and improve soil fertility by adjusting the types and dosages of microbial inoculants and adding soil conditioners.

[0019] 4. The optimized microbial community structure in the present invention can inhibit the growth and reproduction of harmful microorganisms, reduce the occurrence probability of soil-borne diseases, and ensure the healthy growth of crops. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a line graph comparing the straw decomposition rates between the methods for improving soil ecological function provided in the examples and comparative examples of the present invention;

[0021] Figure 2 It is a line graph comparing the improvement of soil organic matter content between the methods for improving soil ecological function provided in the examples and comparative examples of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] Example 1

[0024] 1. Raw material pretreatment: Wheat straw is selected as the raw material. After collection, 100 kg of straw is taken. 20 kg of the straw is pulverized, and microbial inoculant A (the mass ratio of Bacillus subtilis to Trichoderma is 2:1) is added at a ratio of 0.1% of the raw material weight, and microbial inoculant B is added at a ratio of 0.05% of the raw material weight. During the pyrolysis carbonization process, the pyrolysis temperature is controlled at 500 °C, the heating rate is 8 °C / min, and the pyrolysis time is 3 h to fix the microorganisms in the pore structure of the biochar. The remaining 80 kg of straw is pulverized to a length of 3 cm and mixed evenly with the biochar at a mass ratio of 1:5. At the same time, cellulase (the addition amount is 0.05% of the straw weight) and ligninase (the addition amount is 0.03% of the straw weight) are added to the straw and biochar mixture. One week before wheat harvest, a microbial activator is sprayed on the leaf surface at a spraying concentration of 0.2%.

[0025] 2. Field application operation: The treated straw and biochar mixture is evenly spread on the field of loamy fluvo-aquic soil, and then deep plowing is carried out with a depth of 20 cm. After deep plowing, straw is covered on the soil surface with a thickness of 5 cm, and a soil conditioner layer is set in the soil after field application, with an application rate of 150 kg per mu. The soil conditioner is composed of biochar and zeolite mixed at a mass ratio of 3:2.

[0026] 3. Irrigation and fertilization: After field application, the soil moisture sensor is used to monitor the soil moisture in real time, and the irrigation amount is controlled by a combination of drip irrigation and sprinkler irrigation to keep the relative soil water content at 65%. Fertilization is carried out according to the ratio of nitrogen, phosphorus and potassium of 3:1:2. Urea is selected as the nitrogen fertilizer, superphosphate is selected as the phosphorus fertilizer, and potassium sulfate is selected as the potassium fertilizer.

[0027] 4. Monitoring and regulation: The change of soil microbial community is monitored by high-throughput sequencing technology every 15 days, and the soil redox potential is measured by a redox potentiometer. During the monitoring process, if the redox potential deviates from the range of -100 mV to 300 mV, the irrigation amount is adjusted according to the actual situation. When the number of Bacillus in the soil is detected to be less than 1×10 6 cfu / g and the number of Pseudomonas is less than 5×10 5 cfu / g, microbial inoculant B is topdressed.

[0028] Example 2

[0029] 1. Raw material pretreatment: Use corn straw as the raw material and collect 150 kg. Take 30 kg of straw and crush it. Add microbial agent A (the mass ratio of Bacillus subtilis to Trichoderma is 2:1, and the addition amount is 0.1% of the raw material weight) and microbial agent B (the addition amount is 0.05% of the raw material weight). During pyrolytic carbonization, control the temperature at 450 °C, the heating rate at 6 °C / min, and the pyrolysis time at 3.5 h. Crush the remaining 120 kg of straw to a length of 2 cm, mix it evenly with biochar at a mass ratio of 1:4, and add the corresponding bioenzyme. Before corn harvest, spray the microbial activator as required.

[0030] 2. Returning to the field operation: Conduct the returning-to-field operation on sandy fluvo-aquic soil. After spreading the straw and biochar mixture, plow deeply by 18 cm, cover the straw by 4 cm, and add soil conditioner.

[0031] 3. Irrigation and fertilization: Control the relative soil water content at 60% through monitoring, and use a combination of drip irrigation and sprinkler irrigation to fertilize in proportion.

[0032] 4. Monitoring and regulation: Regularly monitor the soil microbial community and redox potential, and conduct regulation according to the standards.

[0033] Example 3

[0034] Raw material pretreatment: Select rice straw as the raw material and collect 200 kg in total. Take 50 kg of straw and crush it. Add microbial agent A (the mass ratio of Bacillus subtilis to Trichoderma is 2:1, and the addition amount is 0.1% of the raw material weight) and microbial agent B (the addition amount is 0.05% of the raw material weight), and conduct pyrolytic carbonization. During the pyrolysis process, control the temperature at 550 °C, set the heating rate at 7 °C / min, and the pyrolysis time at 3 h. Then, crush the remaining 150 kg of straw to a length of 4 cm, mix it evenly with biochar at a mass ratio of 1:6, and add cellulase (the addition amount is 0.05% of the straw weight) and ligninase (the addition amount is 0.03% of the straw weight). Ten days before rice harvest, spray the microbial activator with a concentration of 0.2% on the leaf surface.

[0035] Returning to the field operation: Conduct the returning-to-field operation in the experimental field of acidic red soil. Evenly spread the treated straw and biochar mixture on the soil surface, and then conduct deep plowing with a depth of 22 cm. After the deep plowing is completed, cover the straw on the soil surface with a thickness of 6 cm. At the same time, lay a soil conditioner layer (the mass ratio of biochar to zeolite is 3:2, and the application amount per mu is 150 kg) in the soil after returning to the field.

[0036] Irrigation and fertilization: The soil moisture is monitored in real time using a soil moisture sensor. A combination of drip irrigation and sprinkler irrigation is adopted to stably control the relative soil water content at 70%. Fertilizer is applied in the ratio of nitrogen, phosphorus, and potassium of 3:1:2. Urea is selected as the nitrogen fertilizer, superphosphate as the phosphorus fertilizer, and potassium sulfate as the potassium fertilizer.

[0037] Monitoring and regulation: The changes in the soil microbial community are monitored every 15 days using high-throughput sequencing technology, and at the same time, a redox potentiometer is used to measure the soil redox potential. Once the redox potential deviates from the range of -100 mV to 300 mV, it is immediately adjusted by regulating the irrigation volume. When the number of Bacillus in the soil is detected to be less than 1×10 6 cfu / g and the number of Pseudomonas is less than 5×10 5 cfu / g, the microbial agent B is promptly topdressed.

[0038] Control example 1 (without adding microbial agents A and B)

[0039] Raw material pretreatment: Similarly, 200 kg of rice straw is selected. 50 kg of the straw is directly pyrolyzed and carbonized after being crushed. The pyrolysis temperature is 550 °C, the heating rate is 7 °C / min, and the pyrolysis time is 3 h. The remaining 150 kg of straw is crushed to 4 cm and mixed with biochar at a ratio of 1:6. Cellulase and ligninase are added, and a microbial activator is sprayed 10 days before rice harvest.

[0040] Returning to the field operation: In the same acidic red soil test field as in Example 3, the operation steps are the same.

[0041] Irrigation and fertilization: The same irrigation and fertilization methods as in Example 3 are maintained.

[0042] Monitoring and regulation: The monitoring methods and frequencies are the same as in Example 3, but the operation of topdressing microbial agents due to changes in the number of microorganisms is not carried out.

[0043] Control example 2 (without adding bioenzymes)

[0044] Raw material pretreatment: 200 kg of rice straw is taken. 50 kg of the straw is pyrolyzed and carbonized after adding microbial agents A and B, with the same parameters as in Example 3. The remaining 150 kg of straw is crushed to 4 cm and mixed with biochar at a ratio of 1:6. A microbial activator is sprayed 10 days before rice harvest, but cellulase and ligninase are not added.

[0045] Returning to the field operation: In the acidic red soil test field, the operation is the same as in Example 3.

[0046] Irrigation and fertilization: The same irrigation and fertilization plan as in Example 3 is adopted.

[0047] Monitoring and regulation: The monitoring methods and frequencies are the same as in Example 3. The redox potential is regulated according to the standard, and microbial agent B is topdressed as required when the number of microorganisms changes.

[0048] Comparative Example 3 (without pyrolytic carbonization for fixing microorganisms)

[0049] Raw material pretreatment: 200 kg of rice straw was collected. 50 kg of the straw was directly crushed, and microbial agents A and B, cellulase, and ligninase were directly added thereto. The remaining 150 kg of straw was crushed to 4 cm and mixed with the above. 10 days before rice harvest, a microbial activator was sprayed.

[0050] Returning to the field operation: In the acidic red soil test field, the operation was the same as that in Example 3.

[0051] Irrigation and fertilization: The irrigation and fertilization methods were the same as those in Example 3.

[0052] Monitoring and regulation: The monitoring methods and frequencies were the same as those in Example 3. According to the standards, the redox potential was regulated, the microbial quantity was monitored, and microbial agents were topdressed.

[0053] The comparative experimental data of the above various examples and comparative examples are as follows in the table:

[0054]

[0055] Analysis of the experimental data shows that Examples 1 - 3 are significantly superior to Comparative Examples 1 - 3 in all indicators. In terms of soil microbial diversity, the Shannon index of the examples is higher, indicating that their microbial communities are richer and the ecosystem is more stable; in terms of the quantity of beneficial microorganisms, the contents of Bacillus and Pseudomonas in the examples are far higher than those in the comparative examples, which benefits from technologies such as microbial agents, bioenzymes, and pyrolytic carbonization for fixing microorganisms; in terms of the straw decomposition rate and soil organic matter content, the examples also perform better, which is conducive to improving soil fertility; finally, reflected in the crop yield, the examples are significantly higher than the comparative examples. This fully proves that a series of technical means adopted in the present invention, including adding microbial agents, bioenzymes, and pyrolytic carbonization for fixing microorganisms, can effectively adjust the soil microbial mechanism, optimize the soil environment, promote straw decomposition and nutrient release, and thus significantly increase the crop yield.

[0056] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non - restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A method for promoting microbial balance and enhancing soil ecological functions by returning straw to the field, characterized in that, It includes the following steps: (1) Raw material pretreatment: Harvest and collect crop straw as raw material, take part of the straw and crush it, add microbial inoculant A and microbial inoculant B to the straw, and carry out pyrolytic carbonization to fix the microorganisms in the pore structure of biochar. Microbial inoculant A contains Bacillus subtilis and Trichoderma; Microbial inoculant B contains Bacillus and Pseudomonas; Crush the remaining straw to a length of 2 - 4 cm and mix it evenly with biochar. The mass ratio of biochar to straw is 1:4 - 6; (2) Returning to the field operation: Evenly spread the treated straw and biochar mixture on the soil surface, and then carry out deep plowing. The deep plowing depth is 18 - 22 cm; (3) Irrigation and fertilization: After returning to the field, use a soil moisture sensor to monitor in real time, control the irrigation amount to keep the relative soil water content at 60% - 70%, and fertilize according to the ratio of nitrogen, phosphorus and potassium of 3:1:2; (4) Monitoring and regulation: Use high-throughput sequencing technology to monitor the changes in soil microbial communities every 15 days, and at the same time measure the soil redox potential with a redox potentiometer.

2. The method for promoting microbial balance and enhancing soil ecological functions by returning straw to the field according to claim 1, wherein, In step (1), the addition amount of microbial inoculant A is 0.1% of the raw material weight, and the addition amount of microbial inoculant B is 0.05% of the raw material weight; The mass ratio of the Bacillus subtilis to Trichoderma is 2:1; The pyrolysis temperature is controlled at 400 - 600 °C, the heating rate is 5 - 10 °C / min, and the pyrolysis time is 2 - 4 h.

3. The method for promoting microbial balance and enhancing soil ecological function by straw returning to the field according to claim 1, characterized in that, In step (1), add bioenzymes to the straw and biochar mixture. The bioenzymes include cellulase and ligninase. The addition amount of cellulase is 0.05% of the straw weight, and the addition amount of ligninase is 0.03% of the straw weight.

4. A method for returning straw to the field to promote microbial balance and enhance soil ecological functions according to claim 1, characterized in that, In step (1), before harvesting the crop straw, spray a microbial activator on its leaf surface. The microbial activator contains various trace elements and amino acids, and the spraying concentration is 0.2%.

5. A method for promoting microbial balance and enhancing soil ecological functions by returning straw to the field according to claim 1, characterized in that, In step (2), after deep plowing, cover the soil surface with rice straw, and the covering thickness is 4 - 6 cm.

6. The method for promoting microbial balance and improving soil ecological function by returning straw to the field according to claim 1, characterized in that, In step (2), set a soil conditioner layer in the soil after returning to the field. The soil conditioner is a mixture of biochar and zeolite, and the mass ratio of the two is 3:2, and the application amount per mu is 150 kg.

7. A method for promoting microbial balance and enhancing soil ecological functions by returning straw to the field according to claim 1, characterized in that In step (3), urea is selected as the nitrogen fertilizer, superphosphate is selected as the phosphate fertilizer, and potassium sulfate is selected as the potassium fertilizer.

8. A method for returning straw to the field to promote microbial balance and enhance soil ecological functions according to claim 1, characterized in that, In step (3), during the irrigation process, a combination of drip irrigation and sprinkler irrigation is adopted.

9. A method for returning straw to the field to promote microbial balance and enhance soil ecological functions according to claim 1, characterized in that, In step (4), when the redox potential deviates from the range of -100 mV to 300 mV, adjust the soil redox potential by adjusting the irrigation amount or adding a redox regulator.

10. A method for promoting microbial balance and enhancing soil ecological functions by returning straw to the field according to claim 1, characterized in that, In step (4), when the Bacillus in the soil is detected to be less than 1×10 6 cfu / g and the Pseudomonas is less than 5×10 5 cfu / g, apply microbial inoculant B as topdressing.

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