Method for reducing greenhouse gas emission of rice soil

Abstract

The invention belongs to the technical field of greenhouse gas emission reduction, and provides a method for reducing greenhouse gas emission of rice soil. The method comprises the following steps that a microbial electrochemical breather pipe is vertically inserted into rice field soil, the microbial electrochemical breather pipe is composed of a carbon rod and a carbon felt, the carbon rod is vertically placed and extends out of the surface of the soil, and the carbon felt is buried in the soil; a water layer is arranged on the soil surface of the rice field, the waterflooding environment of rice soil is simulated, and cultivation is conducted in the waterflooding environment. The carbon rods are used for inducing electron transfer in the rice field soil, transmission of electrons from the bottom soil to the surface soil is accelerated, the electron transfer mode effectively inhibits the methane production process of the bottom anaerobic zone, and the methane production dynamics is changed by adjusting the competition of soil microorganisms, so that the methane production efficiency is improved. The method is different from a traditional method for inhibiting methane emission through chemical additives or exogenous microorganisms, and methane inhibition in the natural soil environment is achieved through physical action.

Description

Technical Field

[0001] The invention relates to the technical field of greenhouse gas emission reduction, and in particular to a method for reducing greenhouse gas emission from paddy soil. Background Art

[0002] Methane (CH4) and nitrous oxide (N2O) are important greenhouse gases that cause global climate change. Their 20-year warming effects are 84 times and 264 times that of carbon dioxide (CO2), respectively. In recent years, countries around the world have successively announced their "double carbon" (carbon peak and carbon neutrality) voluntary emission reduction targets and implemented carbon neutrality action plans, committed to slowing global warming. China is an active promoter of the "carbon neutrality" action. Greenhouse gases released from agricultural sources account for more than 17% of my country's greenhouse gas emissions. As the largest anthropogenic wetland system, rice fields provide a good anaerobic environment for the emission of greenhouse gases such as methane; in agricultural greenhouse gas emissions, the greenhouse gas effect of rice fields is 1.6 times that of corn and 4.6 times that of wheat. Therefore, carbon sequestration and emission reduction in the agricultural and rural areas is to achieve energy conservation and emission reduction in the planting industry with a focus on the main rice producing areas on the basis of strengthening food security. Effectively reducing the methane emission intensity of rice fields is one of the core contents of carbon sequestration and emission reduction in agriculture and rural areas. Therefore, it is crucial to study how to reduce greenhouse gas emissions from paddy soil.

[0003] At present, the main ways to reduce greenhouse gas emissions include changing land use, increasing field management measures and applying emission reduction materials. Changing land use, such as changing land from rice planting in paddy fields to fruit tree planting in orchards, can significantly reduce methane emission flux, but will increase nitrous oxide emission flux, and fail to fundamentally reduce greenhouse gas emissions. Field management measures such as fertilization, irrigation and pesticide application are also commonly used greenhouse gas emission control measures. They can alleviate methane emission flux to a certain extent, but will increase soil health risks and may also cause food security problems such as pesticide residues. Applying emission reduction materials is a potential effective way to mitigate greenhouse gas emissions from rice fields. These materials are mainly divided into soil improvement, oxygenation, methanogen inhibition and electron acceptor. As a soil conditioner, biochar has the potential to reduce greenhouse gas emissions. The soil carbon sequestration effect of biochar is mainly based on its high degree of aromatization and strong stability. After being applied to the soil, it can be stably present in the soil for decades to thousands of years, while increasing the soil stable carbon pool reserves and achieving carbon sequestration. Although biochar can reduce methane emissions, it promotes the process of ammonia oxidation to produce nitrous oxide in paddy soil under anaerobic conditions, increasing nitrous oxide emissions. Oxygen-enhancing substances such as calcium peroxide can effectively reduce the total amount of reducing substances in paddy soil and increase the concentration of active oxygen, but the addition of calcium peroxide has a poor effect on inhibiting methane emissions in the later stage, and coating is required to prolong its inhibitory effect on methane emissions from paddy fields. Both methanogen inhibitors and electron acceptors have a great influence on the basic physical and chemical properties of soil.

[0004] Therefore, it is very important to develop a method to effectively reduce greenhouse gas emissions from paddy soil while having less impact on the soil environment and crop growth. Summary of the invention

[0005] The object of the present invention is to provide a method for reducing greenhouse gas emissions from paddy soil in order to overcome the deficiencies of the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for reducing greenhouse gas emissions from paddy soil, comprising the following steps:

[0008] 1) vertically inserting a microbial electrochemical ventilation tube into paddy soil, the microbial electrochemical ventilation tube consisting of a carbon rod and a carbon felt, the carbon rod is vertically placed and extends out of the soil surface, and the carbon felt is buried in the soil;

[0009] 2) A water layer is set on the surface of paddy field soil to simulate the flooded environment of paddy soil and culture is carried out under the flooded environment.

[0010] Preferably, in the microbial electrochemical ventilation tube, the carbon rod vertically passes through the center of the carbon felt, the length of the carbon rod is 90 to 110 mm, the diameter of the carbon rod is 5 to 7 mm, and the carbon felt is a round carbon felt.

[0011] Preferably, the paddy field soil is pretreated paddy field soil, and the pretreatment process of the paddy field soil is: removing impurities from the paddy field soil, and mixing the impurity-removed paddy field soil with water; the impurities include gravel and plant residues.

[0012] Preferably, the carbon rod and carbon felt are independently rinsed with hydrochloric acid, sodium hydroxide solution and water before use, the number of times of rinsing with hydrochloric acid, sodium hydroxide solution and water is independently 3 to 5 times, the concentration of hydrochloric acid is 0.08 to 0.12 mol / L, and the concentration of sodium hydroxide solution is 0.08 to 0.12 mol / L.

[0013] Preferably, the thickness of the paddy field soil is 6 to 9 cm.

[0014] Preferably, the water layer height on the paddy field soil surface is 0.8 to 1.2 cm.

[0015] Preferably, the culture temperature is 23-28°C and the illumination time is 11-13h / d.

[0016] Preferably, during the cultivation period, water is supplemented to maintain the water layer height on the paddy field soil surface at 0.8 to 1.2 cm.

[0017] Preferably, the cultivation method is open, and the water layer on the surface of the paddy field soil is in contact with the air.

[0018] The beneficial effects of the present invention include the following:

[0019] 1) The method of the present invention effectively reduces the emission of methane and carbon dioxide at the same time, and avoids the increase of the emission of other greenhouse gases (such as nitrous oxide). The present invention regulates the electron transfer process in the soil through physical action, regulates methane emissions through electron transfer, and thus achieves efficient and low-cost greenhouse gas emission reduction effects without introducing any exogenous chemicals, significantly reducing interference with the planting environment, and ensuring soil health and food security.

[0020] 2) One of the innovations of the present invention is that carbon rods are used to induce electron transfer in paddy soil, accelerating the transfer of electrons from the bottom soil to the surface soil. This electron transfer method effectively inhibits the methane production process in the bottom anaerobic zone, and changes the dynamics of methane production by regulating the competition of soil microorganisms. This method is different from the traditional method of inhibiting methane emissions through chemical additives or exogenous microorganisms, but achieves methane inhibition in the natural soil environment through physical action. Another innovation of the present invention is that it can reduce the emissions of methane and carbon dioxide at the same time without increasing the emissions of greenhouse gases such as nitrous oxide. By accelerating soil electron transfer, carbon rods induce changes in the transformation pathway of organic matter and promote the decomposition of macromolecular organic matter, but do not immediately cause complete oxidation of organic matter, directly inhibiting the production of methane without promoting the methane oxidation process, thereby achieving the dual reduction goals of methane and carbon dioxide emissions and avoiding possible side effects in conventional methods.

[0021] 3) The method of the present invention has low input cost and maintenance cost. The present invention does not need to add any biological or chemical exogenous substances (such as bacterial agents, improvers and buffer solutions, etc.), nor does it need to apply other intervention measures, and can achieve the simultaneous inhibition of methane and carbon dioxide emissions in paddy field soil, and the cost is relatively low. The carbon rod used in the present invention mainly induces accelerated electron transfer in the soil through physical action, and itself hardly participates in chemical changes, has no adverse effects on the soil environment and crop growth, and has little loss during use; the microbial electrochemical ventilation tube is easily separated from the soil and can be recycled and reused, thereby reducing costs.

[0022] 4) The method of the present invention is environmentally friendly and highly safe. The present invention relies solely on the physical conductor effect to accelerate the upward transfer of electrons at the bottom of flooded soil, regulate the competition between microorganisms in the soil, and reduce greenhouse gas emissions without substantially interfering with the original habitat of the soil; the microbial electrochemical ventilation tube induces the upward transfer of electrons generated in the bottom anaerobic zone, and eventually reacts with oxygen in the air to generate water without secondary pollution; at the same time, the ventilation tube device operates under normal growth conditions of paddy soil. Compared with other emission reduction technologies, the conditions are mild and no other harmful substances are produced, and there is no risk of invasion of exogenous microorganisms and heavy metals, which can ensure the simultaneous realization of food security and greenhouse gas emission reduction goals.

[0023] 5) The microbial electrochemical ventilation tube of the present invention has a simple structure, is easy to operate, and is easy to promote and implement. The present invention can be completed by directly inserting the carbon rod into the carbon felt to fix it, and then burying the device in the rice field before flooding; then, the rice and other crops are planted by normal flooding, so as to reduce greenhouse gas emissions during the planting period. The microbial electrochemical ventilation tube of the present invention is buried deep in the soil, and only the carbon rod extends out of the soil surface, which has little interference with the upper layer of the soil and does not affect the growth of crops such as rice on the surface of the soil. At the same time, it has a wide range of applicability, and can achieve good greenhouse gas emission reduction effects in common flooded soil environments such as paddy fields, lakes and wetlands. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The microbial electrochemical ventilation tube of the present invention, wherein 1 is a carbon rod, 2 is a carbon felt, and 3 is a gas sampling port;

[0025] Figure 2 : is the methane emission rate during the cultivation period of rice soil in Example 1 (CC) and Comparative Example 1 (CK), where * indicates significant difference between the groups;

[0026] Figure 3 : is the methane emission during the cultivation period of rice soil in Example 1 (CC) and Comparative Example 1 (CK), where * indicates significant difference between the groups;

[0027] Figure 4 : CO2 emission rate during rice soil cultivation in Example 1 (CC) and Comparative Example 1 (CK), where * indicates significant difference between the groups;

[0028] Figure 5 : CO2 emissions during rice soil cultivation in Example 1 (CC) and Comparative Example 1 (CK), where * indicates significant differences between the groups;

[0029] Figure 6 is the emission rate of nitrous oxide during cultivation in the rice soil of Example 1 (CC) and Comparative Example 1 (CK);

[0030] Figure 7The emission of nitrous oxide during cultivation in rice soil of Example 1 (CC) and Comparative Example 1 (CK). DETAILED DESCRIPTION

[0031] The present invention provides a method for reducing greenhouse gas emissions from paddy soil, comprising the following steps:

[0032] 1) vertically inserting a microbial electrochemical ventilation tube into paddy soil, the microbial electrochemical ventilation tube consisting of a carbon rod and a carbon felt, the carbon rod is vertically placed and extends out of the soil surface, and the carbon felt is buried in the soil;

[0033] 2) A water layer is set on the surface of paddy field soil to simulate the flooded environment of paddy soil and culture is carried out under the flooded environment.

[0034] In the present invention, in the microbial electrochemical ventilation tube, the carbon rod preferably passes vertically through the center of the carbon felt, and the length of the carbon rod is preferably 90-110 mm, more preferably 95-105 mm, and more preferably 100 mm; the diameter of the carbon rod is preferably 5-7 mm, more preferably 5.5-6.5 mm, and more preferably 6 mm; the carbon felt is preferably a circular carbon felt.

[0035] In the present invention, the carbon felt is the anode.

[0036] In the present invention, by adjusting the number of carbon rods and the area of ​​carbon felt, it is suitable for reducing greenhouse gas emissions from paddy fields of different areas, thereby achieving the goal of reducing greenhouse gas emissions from paddy fields of large areas.

[0037] In the present invention, carbon rods are used to promote the transfer of electrons in the soil from the bottom anaerobic area to the surface layer, inhibit the activity of methanogens, and promote the enrichment of electroactive microorganisms, thereby reducing the emissions of methane and carbon dioxide without increasing the emissions of nitrous oxide.

[0038] In the present invention, the paddy field soil is preferably pretreated paddy field soil, and the pretreatment process of the paddy field soil is preferably: removing impurities from the paddy field soil, and mixing the impurity-removed paddy field soil with water; the impurities include gravel and plant residues.

[0039] In the present invention, the mass volume ratio of the de-impurated paddy field soil and water is preferably 400 g:180-220 mL, more preferably 400 g:190-210 mL, and even more preferably 400 g:200 mL.

[0040] In the present invention, the carbon rod and carbon felt are preferably independently rinsed with hydrochloric acid, sodium hydroxide solution and water before use. The number of times of rinsing with hydrochloric acid, sodium hydroxide solution and water is independently preferably 3 to 5 times, and more preferably 4 times. The concentration of hydrochloric acid is preferably 0.08 to 0.12 mol / L, more preferably 0.09 to 0.11 mol / L, and more preferably 0.1 mol / L. The concentration of sodium hydroxide solution is preferably 0.08 to 0.12 mol / L, more preferably 0.09 to 0.11 mol / L, and more preferably 0.1 mol / L.

[0041] In the present invention, the thickness of the paddy field soil is preferably 6 to 9 cm, more preferably 7 to 8 cm, and even more preferably 7.5 cm.

[0042] In the present invention, the height of the water layer on the paddy field soil surface is preferably 0.8 to 1.2 cm, more preferably 0.9 to 1.1 cm, and even more preferably 1 cm.

[0043] In the present invention, the culture temperature is preferably 23-28°C, more preferably 24-26°C, more preferably 25°C, and the light exposure time is preferably 11-13 h / d, more preferably 11.5-12.5 h / d, more preferably 12 h / d.

[0044] In the present invention, during the culture period, water is supplemented to maintain the water layer height on the paddy field soil surface preferably at 0.8 to 1.2 cm, more preferably at 0.9 to 1.1 cm, and even more preferably at 1 cm.

[0045] In the present invention, the cultivation method is preferably open, and the water layer on the surface of the paddy field soil is in contact with the air to replenish the consumed oxygen.

[0046] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0047] In the embodiments and comparative examples, soil samples were collected from paddy field soil in Changsha City, Hunan Province (28°72′N, 112°30′E); gravel and plant residues were removed from the paddy field soil samples.

[0048] Example 1

[0049] The microbial electrochemical ventilation tube consists of a carbon rod with a length of 100 mm and a diameter of 6 mm and a circular carbon felt anode (with a diameter of 50 mm) planted at the bottom. The carbon rod passes vertically through the center of the carbon felt. Before use, the carbon rod and carbon felt are rinsed with 0.1 mol / L hydrochloric acid, 0.1 mol / L sodium hydroxide aqueous solution and deionized water in turn. The hydrochloric acid, sodium hydroxide aqueous solution and deionized water are rinsed 4 times respectively to remove surface impurities of the carbon rod and carbon felt.

[0050] 400g of paddy soil from which impurities were removed was stirred and mixed with 200mL of deionized water to obtain mixed paddy soil. After adding the mixed paddy soil (the thickness of the mixed paddy soil was 2cm) to a glass jar with a diameter of 9cm and a height of 15cm, the microbial electrochemical vent was vertically inserted into the paddy soil, the carbon rod was placed vertically and extended out of the soil surface, the carbon felt was buried in the soil, and then the remaining 5cm thick paddy soil was added. The paddy soil surface was covered with deionized water (water layer height 1cm, the height was marked outside the jar), simulating the flooded environment of paddy soil, as a vent CC treatment.

[0051] Comparative Example 1

[0052] Comparative Example 1 The microbial electrochemical ventilation tube was omitted, and 400 g of paddy field soil and 200 mL of deionized water were stirred and mixed to obtain a mixed paddy field soil. The mixed paddy field soil was placed in a glass wide-mouth bottle with a diameter of 9 cm and a height of 15 cm. The paddy field soil depth after placement was 7 cm. Deionized water was added to cover the paddy field soil surface (the water layer height was 1 cm, and the height was marked on the outside of the wide-mouth bottle) to simulate the flooded environment of paddy soil, which was used as the control group CK treatment.

[0053] The treatment group (CC) of Example 1 and the control group (CK) of Comparative Example 1 were cultured in an incubator (temperature 25°C, light 12h / d) simulating a paddy soil environment for 28 days. The height of the water layer was marked on the outside of the glass jar, and water was regularly added to the glass jar to the marked position during the culture period, simulating the flooded environment of paddy soil. Except for sampling, the incubator was kept open for culture, and the water layer on the surface of the paddy soil was in contact with the air to replenish the consumed oxygen.

[0054] When sampling, the glass jar in the incubator was sealed with a lid with a gas sampling port for 24 hours, and the remaining time was kept open for cultivation. 20 mL of headspace gas was sampled from the glass jar on the 1st, 3rd, 7th, 14th and 28th day, and the concentrations of CH4, CO2 and N2O were measured. The concentrations were measured using a gas chromatograph (GC7890B, Agilent, USA) with a front detector FID (flame ionization detector) and a rear detector ECD (electron capture detector). The carrier gas of the front detector FID is 99.999% high-purity N2, the working temperature of the detector is 250℃, the combustion gas is 99.999% high-purity H2, the flow rate is 50mL / min, and the combustion gas is 99.999% high-purity air, the flow rate is 400mL / min; the carrier gas of the rear detector ECD is 99.999% high-purity N2, the tail gas is argon methane (the volume ratio of Ar2 and CH4 is 95:5), and the working temperature of the detector is 300℃. The analytical column of the gas chromatograph is a Porpak.Q packed column, and the column temperature is 50℃.

[0055] The emission rates of greenhouse gases from paddy field soil in Example 1 and Comparative Example 1 were calculated based on the concentrations of CH4, CO2 and N2O in the gas samples. The calculation formula is as follows:

[0056] The calculation formula for the emission rate of CH4 and CO2 is shown in Equation 1:

[0057] R CH4(CO2) =(ρ×C×V×273) / [m×(273+θ)×t] Formula 1

[0058] In formula 1, R CH4(CO2) is the emission rate of the gas being measured, mg·kg -1 ·d -1 ; ρ is the density of the gas under standard conditions (CH4 = 0.717 kg / m 3 , CO2=1.97kg / m 3 ); C is the concentration of the gas being measured, mL / m 3 ; V is the effective space of the gas in the culture bottle, m 3 ; m is the weight of dry soil in the culture bottle, kg; θ is the temperature of the measuring gas, ℃; t is the culture time, d.

[0059] The calculation formula of N2O emission rate is shown in formula 2:

[0060] R N2O =(ρ×C×(V g +V l ×α)×273) / [m×(273+θ)×t] Formula 2

[0061] In formula 2, R N2O is the N2O emission rate, mg·kg -1 ·d -1 ; ρ is the density of N2O under standard conditions, 1.25kg / m 3 ; C is N2O gas concentration, mL / m 3 ; V g is the effective space volume above the culture bottle, m 3 ; V l is the volume of the liquid, m 3 ; α is the Bunsen correction coefficient, which is 0.472 at 30℃; m is the weight of dry soil in the culture bottle, kg; θ is the temperature of the measuring gas, ℃; t is the culture time, d.

[0062] Figure 2 is the methane emission rate during the rice soil cultivation of Example 1 (CC) and Comparative Example 1 (CK), Figure 3 is the methane emission during the cultivation period of rice soil in Example 1 (CC) and Comparative Example 1 (CK), where * indicates significant difference between the groups. Figure 2and 3 It can be seen that Example 1 (CC) significantly reduced the methane emission of paddy soil. In the early stage of cultivation (<3d), the methane emission rate of Example 1 (CC) was similar to that of Comparative Example 1 (CK). As the cultivation progressed, the methane emission rate of CK increased rapidly and was always higher than that of CC. On the 14th day, the methane emission rates of paddy soils in both treatments reached a peak, and the methane emission rate in CC decreased by 30 mg kg -1 ·d -1 This may be due to the reduction of easily degradable carbon sources in the soil. After 28 days of cultivation, compared with CK (1312 mg kg -1 ) compared to the cumulative methane emissions of CC (775 mg kg -1 ) was reduced by 41%, reaching a statistically significant level (p<0.05). Calculated according to the global warming potential value, it is equivalent to a reduction of 14985 mg·kg -1 This indicates that carbon rods transfer electrons from the bottom soil to the surface soil, which is not conducive to the methane production process in the bottom anaerobic zone and has a significant inhibitory effect on methane emissions from paddy field soil.

[0063] Figure 4 is the emission rate of carbon dioxide during cultivation in the rice soil of Example 1 (CC) and Comparative Example 1 (CK), Figure 5 is the carbon dioxide emission during the rice soil cultivation period of Example 1 (CC) and Comparative Example 1 (CK), where * indicates significant difference between the groups. Figure 4 and Figure 5 It can be seen that compared with comparative example 1 (CK), the microbial electrochemical ventilation tube (CC) treatment in Example 1 reduced 1359 mg·kg -1 CO2 emissions; the CO2 emission rate of the CC group reached its peak 7 days later than that of CK. On the 14th and 28th days, the CO2 emission rates of CC decreased by 54% and 52% respectively compared with CK (p<0.05). The microbial electrochemical ventilation tube induced changes in the organic matter transformation pathway by regulating electron transfer and promoted the decomposition of macromolecular organic matter, but did not promote the complete oxidation of organic matter in a short period of time. During the cultivation period, the CO2 emissions of Example 1 were 13-45% lower than that of Comparative Example 1 (p<0.05), which indicates that the microbial electrochemical ventilation tube treatment reduced CH4 emissions without increasing CH4 oxidation.

[0064] Figure 6 is the emission rate of nitrous oxide during cultivation in the rice soil of Example 1 (CC) and Comparative Example 1 (CK), Figure 7 is the emission of nitrous oxide during cultivation in the rice soil of Example 1 (CC) and Comparative Example 1 (CK). Figure 6 and Figure 7It can be seen that during the cultivation period, there was no significant difference in the cumulative N2O emissions and emission rates between CC and CK, that is, the microbial electrochemical aeration tube treatment had no significant effect on N2O emissions from paddy soil, which indicates that the microbial electrochemical aeration tube did not promote nitrous oxide emissions while inhibiting methane emissions from paddy soil.

[0065] Example 2

[0066] The microbial electrochemical ventilation tube consists of two carbon rods with a length of 95 mm and a diameter of 5.5 mm and a circular carbon felt anode (with a diameter of 45 mm) planted at the bottom. The carbon rod passes vertically through the center of the carbon felt. Before use, the carbon rod and carbon felt are rinsed with 0.09 mol / L hydrochloric acid, 0.09 mol / L sodium hydroxide aqueous solution and deionized water in turn. The hydrochloric acid, sodium hydroxide aqueous solution and deionized water are rinsed 5 times respectively to remove surface impurities of the carbon rod and carbon felt.

[0067] 400 g of impurity-removed paddy soil was stirred and mixed with 200 mL of deionized water to obtain mixed paddy soil. After adding the mixed paddy soil to a glass jar with a diameter of 9 cm and a height of 15 cm (the thickness of the mixed paddy soil was 2 cm), the microbial electrochemical ventilation tube was vertically inserted into the paddy soil, the carbon rod was placed vertically and extended out of the soil surface, the carbon felt was buried in the soil, and then the remaining 5 cm thick paddy soil was added. The surface of the paddy soil was covered with deionized water (the water layer height was 1 cm, and the height was marked on the outside of the jar) to simulate the flooded environment of paddy soil. The culture was carried out for 28 days in an incubator (temperature 23°C, light 11.5h / d) simulating the paddy soil environment.

[0068] Example 3

[0069] The microbial electrochemical ventilation tube consists of a carbon rod with a length of 105 mm and a diameter of 6.5 mm and a circular carbon felt anode (diameter of 55 mm) planted at the bottom. The carbon rod passes vertically through the center of the carbon felt. Before use, the carbon rod and carbon felt are rinsed with 0.11 mol / L hydrochloric acid, 0.11 mol / L sodium hydroxide aqueous solution and deionized water in turn. The hydrochloric acid, sodium hydroxide aqueous solution and deionized water are rinsed three times respectively to remove surface impurities of the carbon rod and carbon felt.

[0070] 400 g of impurity-removed paddy soil was stirred and mixed with 200 mL of deionized water to obtain mixed paddy soil. After adding the mixed paddy soil to a glass jar with a diameter of 9 cm and a height of 15 cm (the thickness of the mixed paddy soil was 2 cm), the microbial electrochemical ventilation tube was vertically inserted into the paddy soil, the carbon rod was placed vertically and extended out of the soil surface, the carbon felt was buried in the soil, and then the remaining 5 cm thick paddy soil was added. The surface of the paddy soil was covered with deionized water (the water layer height was 1 cm, and the height was marked on the outside of the jar) to simulate the flooded environment of paddy soil. The culture was carried out for 28 days in an incubator (temperature 28°C, light 12.5h / d) simulating the paddy soil environment.

[0071] The present invention is based on the theory of microbial electrochemical extracellular electron transfer, using the soil's own organic matter as an electron source, a conductive carbon rod as a conductive material and an electron transmission channel, i.e., a vent, and oxygen in the air as an electron acceptor to achieve efficient transfer of soil electrons, thereby directionally enriching electroactive microorganisms in the soil microenvironment, allowing them to compete with methanogens for electrons, significantly reducing the amount of methane generated, and ultimately achieving in situ inhibition of soil methane production by regulating soil microbial communities and functions. At the same time, by regulating the soil microbial metabolic pathways and microbial community functions, excessive decomposition of organic matter is inhibited, thereby reducing carbon dioxide emissions. The present invention does not cause a significant increase in nitrous oxide during the reduction of methane and carbon dioxide, reflecting significant environmental friendliness and technical superiority. The method of the present invention can provide a new technical approach for greenhouse gas emission reduction in rice fields and soil carbon sequestration, and contribute scientific solutions to achieving the "dual carbon" goals in the agricultural field and global climate governance.

[0072] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for reducing greenhouse gas emissions from paddy soil, characterized in that: The following steps are included: 1) vertically inserting a microbial electrochemical ventilation tube into paddy soil, the microbial electrochemical ventilation tube consisting of a carbon rod and a carbon felt, the carbon rod is vertically placed and extends out of the soil surface, and the carbon felt is buried in the soil; 2) A water layer is set on the surface of paddy field soil to simulate the flooded environment of paddy soil and culture is carried out under the flooded environment.

2. The method according to claim 1, characterized in that In the microbial electrochemical ventilation tube, the carbon rod vertically passes through the center of the carbon felt, the length of the carbon rod is 90 to 110 mm, the diameter of the carbon rod is 5 to 7 mm, and the carbon felt is a round carbon felt.

3. The method according to claim 2, characterized in that The paddy field soil is pretreated paddy field soil, and the pretreatment process of the paddy field soil is: removing impurities from the paddy field soil, and mixing the impurity-removed paddy field soil with water; the impurities include gravel and plant residues.

4. The method according to claim 1, characterized in that: The carbon rod and carbon felt are independently rinsed with hydrochloric acid, sodium hydroxide solution and water before use. The number of times of rinsing with hydrochloric acid, sodium hydroxide solution and water is independently 3 to 5 times. The concentration of hydrochloric acid is 0.08 to 0.12 mol / L, and the concentration of sodium hydroxide solution is 0.08 to 0.12 mol / L.

5. The method according to claim 4, characterized in that The thickness of paddy field soil is 6 to 9 cm.

6. The method according to claim 1 or 5, characterized in that: The water layer height on the surface of paddy field soil is 0.8 to 1.2 cm.

7. The method according to claim 6, characterized in that The culture temperature is 23-28° C., and the light exposure time is 11-13 h / d.

8. The method according to claim 7, characterized in that During the cultivation period, water was added to keep the water layer height on the paddy field soil surface at 0.8 to 1.2 cm.

9. The method according to claim 7 or 8, characterized in that: The cultivation method is open, and the water layer on the surface of the rice field soil is in contact with the air.

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