Method suitable for reducing N2O emission of medium-weak acid soil after straw returning to field

Abstract

The invention discloses a method suitable for reducing N2O emission of medium-weak acid soil after straw returning, and relates to the technical field of environmental protection. According to the method, the adopted medium-weak acid soil is the soil which is completely smashed, buried and returned to the field, after the medium-weak acid soil is pre-cultured, the nitrogen fertilizer and the inhibitor are sequentially applied to the pre-cultured medium-weak acid soil, and the emission of N2O in the medium-weak acid soil is reduced through culture. Wherein the inhibitor is prepared by compounding 3, 4-dimethyl pyrazole phosphate and a nano carbon solution. The 3, 4-dimethylpyrazole phosphate and the nanocarbon solution are compounded to achieve a synergistic effect on reducing the total discharge amount of N2O in the medium-weak acid soil. Specifically, compared with a blank treatment group, the inhibitor prepared by combining the 3, 4-dimethyl pyrazole phosphate and the nano carbon solution has the advantage that the discharge amount of N2O is reduced by 0.422 kg.hm <-2 >.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection, and in particular to a method suitable for reducing soil N2O emission after returning straw to the field in medium-weakly acidic soil. Background Art

[0002] Nitrous oxide (N2O) is one of the most important greenhouse gases in the atmosphere, and its warming trend is 265-298 times that of CO2. N2O emissions mainly come from agricultural soils. The widespread use of nitrogen fertilizers has driven the growth of soil N2O emissions, accounting for 60-70% of total atmospheric emissions, and has a significant impact on the global greenhouse effect.

[0003] As a protective tillage measure, returning straw to the field has the effects of improving soil structure, increasing soil nutrient content, promoting crop yield, increasing direct input of soil organic carbon to achieve carbon fixation, maintaining soil organic matter balance, and promoting soil nutrient cycling. The paper "Study on the Effect of Returning Straw to the Field and Its Impact on the Biological Release Path of N2O" (Qu Zhaoqi, Shandong Agricultural University, May 2024) is based on three straw return methods: no return of straw to the field, only wheat straw return to the field, and full return of wheat and corn straw to the field, six return amounts of no return to the field, return to the field every other year, half return to the field, full return to the field, 1.5 times the amount, and double the amount, as well as four return modes of no return to the field, crushing and burying, deep plowing and composting, and composting. Field experiments were carried out in medium and weak acidic soils to study the effect of returning straw to the field on N2O emissions. The results showed that no matter which type of straw return treatment, N2O emissions will increase, and the total N2O emissions will increase by 3.67-24.76%. The full-amount crushing and burying of straw is the main technical model for returning straw to the fields in the Huanghuaihai region for wheat-corn rotation. Therefore, developing effective N2O emission reduction measures based on this model is of great significance for the rational use of straw and the realization of sustainable agricultural development in the Huanghuaihai region.

[0004] In the prior art, the paper "The Effects of Biochar and Nitrification Inhibitors on N2O and NO Emissions from Organically Managed Vegetable Soils" (Wang Danfeng, Huazhong Agricultural University, June 2023) discloses that the combined use of biochar and nitrification inhibitors can significantly affect the physical and chemical properties of tropical vegetable soils and the conversion of soil inorganic carbon, thereby affecting N2O emissions. However, the soil targeted in the above paper is tropical vegetable soil. The emission of N2O in this soil is due to the unreasonable and unscientific use of nitrogen fertilizers, which leads to an increase in the soil nitrogen pool load, causing soil nitrogen loss and decreased utilization rate, while promoting N2O emissions. The reason for the increase in N2O emissions in the soil after the full amount of crushed and buried straw is that as the straw gradually decomposes, a large amount of NO3 accumulates in the soil. — N provides abundant substrates for nitrifying and denitrifying microorganisms, promoting the increase of N2O emissions.

[0005] Therefore, how to develop a method suitable for medium-to-weakly acidic soils to reduce soil N2O emissions after returning straw to the fields based on the full-amount crushing and burying soil return model is of great significance for controlling agricultural source pollution and greenhouse gas emissions and achieving ecological sustainable development. Summary of the invention

[0006] In view of the above-mentioned prior art, the purpose of the present invention is to provide a method suitable for reducing soil N2O emissions after returning straw to the field in medium-weak acidic soil. The medium-weak acidic soil in the present invention is soil in which the straw is fully crushed and buried and returned to the field. After pre-cultivation, nitrogen fertilizer and inhibitor are applied to the pre-cultivated soil in sequence, and the emission of nitrous oxide in the medium-weak acidic soil is reduced after cultivation. Wherein, the inhibitor is compounded by 3,4-dimethylpyrazole phosphate (DMPP) and nano-carbon solution. The present invention uses 3,4-dimethylpyrazole phosphate (DMPP) and nano-carbon solution to compound, which has a synergistic effect in reducing the total amount of N2O emissions in medium-weak acidic soil.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] The present invention provides a method for reducing soil N2O emissions after returning straw to the field, which is applicable to medium-weakly acidic soil, and comprises the following steps:

[0009] After pre-cultivating the moderately weakly acidic soil, nitrogen fertilizer is applied to the pre-cultivated moderately weakly acidic soil, and then inhibitors are applied for cultivation to reduce the emission of N2O in the moderately weakly acidic soil;

[0010] The inhibitor comprises a nitrification inhibitor and a nano carbon solution.

[0011] Preferably, the medium to weakly acidic soil is soil in which all the straw powder is turned over and returned to the field.

[0012] Preferably, the operation of pre-culturing the moderately weakly acidic soil is: after screening the moderately weakly acidic soil, adjusting the soil moisture content to 40% of the field water holding capacity, and culturing it at 25° C. and in the dark for 10 days.

[0013] Preferably, the nitrogen fertilizer is urea, and the amount of nitrogen fertilizer applied is 100 μg urea-N·g -1 dws.

[0014] Preferably, the nitrification inhibitor is 3,4-dimethylpyrazole phosphate (DMPP).

[0015] Preferably, the nanocarbon solution is a mixture of nanocarbon and water, the concentration of the nanocarbon solution is 0.0652 mg / mL, and the nanocarbon is purchased from Shanghai Fangdian Biotechnology Co., Ltd.

[0016] Preferably, in the inhibitor, the mass ratio of the nano-carbon in the nano-carbon solution to the nitrification inhibitor is 1:2.

[0017] Preferably, the amount of nitrification inhibitor applied is 1.5% of the nitrogen content in the nitrogen fertilizer, and the amount of nanocarbon in the nanocarbon solution applied is 0.75% of the nitrogen content in the nitrogen fertilizer.

[0018] Preferably, during the culture process, the culture temperature is 25° C., the conditions are dark, and the culture time is 28 days.

[0019] Beneficial effects of the present invention:

[0020] The medium-weakly acidic soil in the present invention is the soil in which the straw is fully crushed, turned over and returned to the field. After pre-cultivation, nitrogen fertilizer and inhibitor are applied to the pre-cultivated soil in sequence, and the emission of N2O in the medium-weakly acidic soil is reduced by cultivation. Wherein, the inhibitor is compounded by 3,4-dimethylpyrazole phosphate (DMPP) and nanocarbon solution. The present invention utilizes the combined application of inhibitors and nitrogen fertilizers to effectively slow down the conversion of ammonium nitrogen to nitrate nitrogen in the soil by inhibiting the activities of soil nitrification and denitrification microorganisms. It is an effective management method commonly used in agricultural production to improve the utilization rate of nitrogen fertilizers and reduce the application of chemical fertilizers.

[0021] The present invention uses a nitrification inhibitor and a nanocarbon solution for medium to weak acidic soils, which has a synergistic effect in reducing the total amount of N2O emissions in the soil. Specifically, compared with the blank treatment group, the N2O emissions in the soil were reduced by 0.233 kg / hm after only using the nitrification inhibitor DMPP for treatment. 2 After treatment with nanocarbon solution alone, the N2O emission in the soil decreased by 0.170 kg / hm 2 , and the present invention uses nitrification inhibitor DMPP and nanocarbon solution for treatment, and the emission of N2O in the soil is reduced by 0.422kg / hm 2 . DETAILED DESCRIPTION

[0022] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0023] At present, different ways of returning to the field, different amounts of returning to the field and different patterns of returning to the field will increase the emission of N2O in medium and weak acidic soils, and the full amount of crushing and burying returning to the field is the main technical pattern of returning wheat-corn rotation straw to the field in the Huanghuaihai region. Therefore, based on the full amount of crushing and burying returning to the field soil returning model, developing effective N2O emission reduction measures is of practical significance for the rational use of straw and the realization of sustainable agricultural development in the Huanghuaihai region.

[0024] Based on this, the present invention selects the wheat-corn rotation area widely existing in the Huanghuaihai region, and the soil where the straw is fully crushed and buried and returned to the field is used as the test soil, and provides a method suitable for reducing the N2O emission of the soil after the straw is returned to the field in the medium-weak acidic soil, comprising the following steps: pre-culturing the medium-weak acidic soil, and then sequentially adding nitrogen fertilizer and inhibitor to the pre-cultured medium-weak acidic soil, and culturing to reduce the emission of N2O in the medium-weak acidic soil. Wherein, the inhibitor includes a nitrification inhibitor and a nanocarbon solution.

[0025] Among them, the nitrification inhibitor is 3,4-dimethylpyrazole phosphate DMPP, which is an off-white powdery substance that is easily adsorbed by soil colloids, migrates slowly in the soil, and is not easily washed by water. It is non-toxic to crops, non-polluting to the soil, and non-irritating to humans. Its biggest advantage is that the nitrification inhibition lasts for a long time and the dosage is small, and the nitrification inhibition efficiency is high. DMPP can effectively reduce the emission of N2O. On the one hand, DMPP delays the conversion process of soil ammonium nitrogen to nitrate nitrogen, thereby reducing the substrate source for soil denitrification; on the other hand, DMPP reduces the emission of soil N2O by inhibiting the activity of AOB and Comammox.

[0026] Nanocarbon is a modified carbon material. As a common nanomaterial, it is well-known for its small size, large surface area and strong adsorption capacity. On the one hand, nanocarbon has a large specific surface area and rich pore structure, which enables it to more effectively adsorb and fix nitrogen in the soil and reduce the production and emission of N2O. On the other hand, nanocarbon is rich in alkaline functional groups, which can effectively improve the physical and chemical properties of soil, reduce soil nutrient loss and improve fertilizer utilization, thereby reducing greenhouse gas emissions from farmland. Nanocarbon is widely present in soil and soil-vegetation-atmosphere cycle, affecting soil structure, element migration in soil and chemical and biological reactions. Nanocarbon can promote the reduction of soil N2O and reduce soil N2O emissions by increasing the abundance of nitrous oxide reductase genes (nosZ) and reducing the ratio of nitrite reductase genes to nitrous oxide reductase genes [(nirS+nirK) / nosZ].

[0027] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0028] The experimental materials used in the embodiments of the present invention are all conventional experimental materials in the art and can be purchased through commercial channels.

[0029] Embodiment 1:

[0030] The medium-slightly acidic soil in which the straw was fully powdered and buried was used as the target soil. The medium-slightly acidic soil was sieved to remove plant residues and stones, and the moisture content of the target soil was adjusted to 40% of the field water holding capacity, and was cultured at 25°C and in the dark for 10 days.

[0031] Urea was applied to the pre-cultured medium-slightly acidic soil at a rate of 100 μg urea-N g - 1 dws, then the inhibitor was applied and cultured at 25 °C in the dark for 28 days to reduce N2O emissions in moderately and slightly acidic soils;

[0032] The inhibitor consists of 3,4-dimethylpyrazole phosphate (DMPP) and a nanocarbon solution, the nanocarbon solution is a mixture of nanocarbon and water, the concentration of the nanocarbon solution is 0.0652 mg / mL, the mass ratio of nanocarbon to 3,4-dimethylpyrazole phosphate (DMPP) in the nanocarbon solution is 1:2, the application amount of 3,4-dimethylpyrazole phosphate (DMPP) is 1.5% of the nitrogen content in the nitrogen fertilizer, and the application amount of nanocarbon in the nanocarbon solution is 0.75% of the nitrogen content in the nitrogen fertilizer.

[0033] Test example: Microcosm cultivation test

[0034] The experiment took the soil from the experimental field of straw crushing and burying in Mazhuang Town, Shandong Province, China as the research object. The 0-20 cm tillage layer soil was collected. The collected soil was sieved (2 mm) to remove plant residues and stones as the test soil and stored at room temperature until use.

[0035] The specific steps are:

[0036] The moisture content of the test soil was adjusted to 40% of the field water holding capacity, that is, 14.0 mL of deionized water was added to every 100 g of dry soil, and the test soil was cultured at 25 °C in the dark for 10 days; 120 g of the pre-cultured soil was transferred to a 1 L glass bottle, and urea was first applied to the pre-cultured test soil at a dosage of 100 μg urea-N g -1 dws, that is, 26.08 mg was added to each bottle, and then the inhibitors in treatment groups 1-4 were applied respectively. At this time, the soil moisture content was 60% of the field water holding capacity. It was cultured at 25°C and dark conditions for 28 days, and ventilated for 5 minutes every 3 days under plastic wrap. The gas was taken on 0, 1, 3, 7, 14, 21, and 28 days, and then the N2O emission flux was determined using a gas chromatograph. Finally, the total N2O emission of each treatment was calculated. The results are shown in Table 1.

[0037] The calculation formula for the total N2O emissions is:

[0038]

[0039] Where E is the total N2O emission, in kg·hm -2 ; F is the gas flux, in μgN2O-N·m -2 ·h -1 , n is the total number of gas measurements, i is the sampling time, (t i+1 -t i ) is the number of days between two gas measurements.

[0040] Among them, this experiment set up four treatment groups, each treatment group set up 3 replicates, as follows:

[0041] Treatment group 1: CK group, using water as an inhibitor;

[0042] Treatment group 2: DMPP group, using only 3,4-dimethylpyrazole phosphate as an inhibitor;

[0043] Treatment group 3: nanocarbon group, using only nanocarbon solution as an inhibitor, wherein the preparation method and concentration of the nanocarbon solution are the same as those in Example 1;

[0044] Treatment group 4: DMPP+nanocarbon group, using a mixture of 3,4-dimethylpyrazole phosphate DMPP and nanocarbon solution as an inhibitor, and the preparation method of the inhibitor is the same as that of Example 1;

[0045] Ensure that the amount of inhibitor applied in each treatment group remains consistent.

[0046] Table 1 N2O emissions in different treatment groups

[0047] Group <![CDATA[N2O emissions (kg·hm -2 )]]> CK group 0.593 DMPP group 0.360 Nanocarbon Group 0.423 DMPP+Nanocarbon Group 0.171

[0048] As can be seen from Table 1, the N2O emission from CK treatment is 0.593 kg hm -2 DMPP treatment of N2O emissions is 0.360kghm -2 , the N2O emission after nanocarbon treatment is 0.423 kg hm -2 DMPP+nanocarbon treatment N2O emissions are 0.171kg hm -2 Compared with the blank treatment group, the N2O emission was reduced by 0.233 kg·hm -2 Using only nanocarbon as an inhibitor, N2O emissions were reduced by 0.170 kg·hm -2 The present invention uses DMPP and nanocarbon compound as inhibitors, and the N2O emission is reduced by 0.422kg·hm -2It can be seen that the present invention uses 3,4-dimethylpyrazole phosphate (DMPP) and nano-carbon solution as an inhibitor, which has a synergistic effect in reducing the total amount of N2O emissions in the soil.

[0049] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for reducing soil N2O emissions after returning straw to the field in moderately or slightly acidic soils, comprising the following steps: After pre-cultivating the moderately weakly acidic soil, nitrogen fertilizer is applied to the pre-cultivated moderately weakly acidic soil, and then inhibitors are applied for cultivation to reduce the emission of N2O in the moderately weakly acidic soil; The inhibitor comprises a nitrification inhibitor and a nano-carbon solution.

2. The method according to claim 1, characterized in that The medium to weak acidic soil is the soil in which the straw is fully powdered and buried in the field.

3. The method according to claim 1, characterized in that The operation of pre-cultivating the medium-slightly acidic soil is as follows: after screening the medium-slightly acidic soil, the soil moisture content is adjusted to 40% of the field water holding capacity, and the soil is placed under 25° C. and dark conditions for 10 days.

4. The method according to claim 1, characterized in that The nitrogen fertilizer is urea, and the amount of nitrogen fertilizer applied is 100 μg urea-N g -1 dws.

5. The method according to claim 1, characterized in that The nitrification inhibitor is 3,4-dimethylpyrazole phosphate; the nanocarbon solution is a mixture of nanocarbon and water, and the concentration of the nanocarbon solution is 0.0652 mg / mL.

6. The method according to claim 1, characterized in that In the inhibitor, the mass ratio of the nano-carbon in the nano-carbon solution to the nitrification inhibitor is 1:

2.

7. The method according to claim 1, characterized in that The amount of nitrification inhibitor applied is 1.5% of the nitrogen content in the nitrogen fertilizer, and the amount of nanocarbon in the nanocarbon solution applied is 0.75% of the nitrogen content in the nitrogen fertilizer.

8. The method according to claim 1, characterized in that During the cultivation process, the cultivation temperature was 25°C, the conditions were dark, and the cultivation time was 28 days.

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