A method suitable for reducing N2O emission of soil after straw returning in medium-weak acid soil

Abstract

The application discloses a method suitable for reducing N2O emission of straw returned to field in medium-weak acidic soil, and relates to the technical field of environmental protection. The medium-weak acidic soil is the straw full amount smashing and burying returned to field soil, and after pre-culturing the medium-weak acidic soil, nitrogen fertilizer and inhibitor are added into the pre-cultured medium-weak acidic soil in sequence, and after culturing, the N2O emission of the medium-weak acidic soil is reduced. The inhibitor is compounded by 3,4-dimethyl pyrazole phosphate and nano carbon solution. The 3,4-dimethyl pyrazole phosphate and the nano carbon solution have a synergistic effect on reducing the total amount of N2O emission in the medium-weak acidic soil. Specifically, compared with the blank treatment group, the N2O emission amount of the inhibitor prepared by combining the 3,4-dimethyl pyrazole phosphate and the nano carbon solution is reduced by 0.422 kg·hm ‑2 .

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and in particular to a method for reducing soil N2O emissions after straw return to the field in moderately to weakly acidic soils. Background Technology

[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 originate from agricultural soils. The widespread use of nitrogen fertilizers has driven the increase in soil N2O emissions, accounting for 60-70% of total atmospheric emissions, and has a significant impact on the global greenhouse effect.

[0003] Returning straw to the field, as a conservation tillage measure, has the effects of improving soil structure, increasing soil nutrient content, promoting crop yield, increasing the direct input of soil organic carbon to achieve carbon sequestration, maintaining soil organic matter balance, and promoting soil nutrient cycling. The paper "The Effects of Straw Returning to the Field and Its Influence on N2O Biological Release Pathways" (Qu Zhaoqi, Shandong Agricultural University, May 2024) conducted a field experiment in moderately acidic soils based on three straw return methods: no straw return, only wheat straw return, and full wheat and corn straw return; six straw return amounts: no return, return every other year, half-quantity return, full-quantity return, 1.5 times the amount, and double the amount; and four straw return modes: no return, crushing and burying, deep plowing, and composting. The results showed that regardless of the straw return treatment, N2O emissions increased, with total N2O emissions increasing by 3.67%–24.76%. As the main straw return technology mode for wheat-corn rotation in the Huang-Huai-Hai region, the complete crushing and burying of straw into the soil is a major feature of straw return technology. Therefore, developing effective N2O emission reduction measures based on this straw return mode is of great significance for the rational utilization of straw and the realization of sustainable agricultural development in the Huang-Huai-Hai region.

[0004] In existing technologies, the paper "The Effects of Biochar and Nitrification Inhibitors on N2O and NO Emissions from Organically Managed Vegetable Fields" (Wang Danfeng, Huazhong Agricultural University, June 2023) discloses that the combined use of biochar and nitrification inhibitors can significantly affect the physicochemical properties and inorganic carbon conversion of tropical vegetable field soils, thereby affecting N2O emissions. However, the soil discussed in the aforementioned paper is tropical vegetable field soil, where N2O emissions are due to the unreasonable and unscientific use of nitrogen fertilizer, leading to an increased soil nitrogen pool load, resulting in nitrogen loss and decreased utilization rate, while simultaneously promoting N2O emissions. The increased N2O emissions in soils where all straw is crushed, plowed, and returned to the field are due to the accumulation of large amounts of NO3 in the soil as straw gradually decomposes. — N provides abundant substrates for nitrifying and denitrifying microorganisms, promoting an increase in N2O emissions.

[0005] Therefore, developing a method to reduce soil N2O emissions after straw return to the field, based on the soil return model of full crushing and burying, is of great significance for controlling agricultural pollution and greenhouse gas emissions and achieving ecological sustainable development. Summary of the Invention

[0006] To address the aforementioned limitations of existing technologies, the present invention aims to provide a method for reducing N2O emissions from moderately acidic soils after straw return to the field. The moderately acidic soil in this invention refers to soil where all straw has been crushed and plowed back into the field. After pre-cultivation, nitrogen fertilizer and an inhibitor are sequentially applied to the pre-cultivated soil, followed by cultivation to reduce nitrous oxide emissions. The inhibitor is a compound of 3,4-dimethylpyrazole phosphate (DMPP) and nano-carbon solution. This invention utilizes a synergistic effect of the compound of 3,4-dimethylpyrazole phosphate (DMPP) and nano-carbon solution in reducing the total N2O emissions from moderately acidic soils.

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

[0008] This invention provides a method for reducing soil N2O emissions after straw return to the field in moderately to weakly acidic soils, comprising the following steps:

[0009] After pre-culturing the moderately acidic soil, nitrogen fertilizer was applied to the pre-cultured moderately acidic soil, and then inhibitors were applied for further cultivation to reduce N2O emissions from the moderately acidic soil.

[0010] The inhibitors include nitration inhibitors and nano-carbon solutions.

[0011] Preferably, the moderately acidic soil is soil in which all straw is pulverized and buried back into the field.

[0012] Preferably, the pre-cultivation operation of the moderately acidic soil is as follows: after screening the moderately acidic soil, the soil moisture content is adjusted to 40% of the field capacity, and it is cultivated in the dark at 25°C for 10 days.

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

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

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

[0016] Preferably, in the inhibitor, the mass ratio of nano-carbon to nitration inhibitor in the nano-carbon solution 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 nano-carbon applied in the nano-carbon solution is 0.75% of the nitrogen content in the nitrogen fertilizer.

[0018] Preferably, the culture process is carried out at a temperature of 25°C in the dark for 28 days.

[0019] The beneficial effects of this invention are:

[0020] The moderately acidic soil in this invention is soil from which all straw has been crushed, plowed, and returned to the field. After pre-cultivation, nitrogen fertilizer and inhibitors are sequentially applied to the pre-cultivated soil, and cultivation is then carried out to reduce N2O emissions in the moderately acidic soil. The inhibitor is a compound of 3,4-dimethylpyrazole phosphate (DMPP) and nano-carbon solution. This 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 activity of soil nitrifying and denitrifying microorganisms. This is a commonly used and effective management method in agricultural production to improve nitrogen fertilizer utilization and reduce chemical fertilizer application.

[0021] This invention employs a combination of nitrification inhibitors and nano-carbon solutions for use in moderately to weakly acidic soils, exhibiting a synergistic effect in reducing total N2O emissions from the soil. Specifically, compared to the control group, treatment with only the nitrification inhibitor DMPP reduced N2O emissions from the soil by 0.233 kg / hm². 2 After treatment with nano-carbon solution alone, the N2O emission in the soil decreased by 0.170 kg / hm². 2 The present invention, by using a combination of nitrification inhibitor DMPP and nano-carbon solution for treatment, reduced N2O emissions in the soil by 0.422 kg / hm². 2 . Detailed Implementation

[0022] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0023] Currently, different methods, amounts, and patterns of straw return to the field all increase N2O emissions in moderately to slightly acidic soils. Complete straw crushing and burying is the primary straw return technology in the Huang-Huai-Hai region during wheat-corn rotation. Therefore, developing effective N2O emission reduction measures based on this straw return model is of practical significance for the rational utilization of straw and the realization of sustainable agricultural development in the Huang-Huai-Hai region.

[0024] Based on this, this invention selects the wheat-corn rotation area, which is widely present in the Huang-Huai-Hai region, and uses soil with all straw crushed and plowed back into the field as experimental soil. It provides a method suitable for reducing soil N2O emissions after straw return in moderately acidic soils, comprising the following steps: pre-culturing the moderately acidic soil, then sequentially adding nitrogen fertilizer and inhibitors to the pre-cultured moderately acidic soil, followed by further culturing to reduce N2O emissions from the moderately acidic soil. The inhibitors include nitrification inhibitors and nano-carbon solutions.

[0025] The nitrification inhibitor is 3,4-dimethylpyrazole phosphate (DMPP), a grayish-white powder that is easily adsorbed by soil colloids, migrates slowly in the soil, and is not easily leached by water. It is non-toxic to crops, does not pollute the soil, and is non-irritating to humans. Its greatest advantage is its long-lasting nitrification inhibition effect with low dosage and high nitrification inhibition efficiency. DMPP effectively reduces N2O emissions because, on the one hand, it slows down the conversion of ammonium nitrogen to nitrate nitrogen in the soil, thus reducing the substrate source for denitrification; on the other hand, it reduces soil N2O emissions by inhibiting the activity of AOB and Commammox.

[0026] Nanocarbon is a modified carbon material. As a common nanomaterial, it is known for its small size, large surface area, and strong adsorption capacity. On the one hand, nanocarbon has a large specific surface area and abundant pore structure, which enables it to more effectively adsorb and fix nitrogen in the soil, reducing 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 the 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 gene (nosZ) and decreasing the ratio of nitrite reductase gene to nitrous oxide reductase gene [(nirS+nirK) / nosZ].

[0027] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

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

[0029] Example 1:

[0030] The target soil was a slightly acidic soil with all straw pulverized and returned to the field. The slightly acidic soil was screened to remove plant residues and stones. The moisture content of the target soil was adjusted to 40% of the field capacity and then placed in the dark at 25°C for 10 days.

[0031] Urea was applied to the pre-cultured, slightly acidic soil at a dosage of 100 μg urea-N·g. - 1 DWS, then apply inhibitors and incubate at 25°C in the dark for 28 days to reduce N2O emissions in moderately acidic soil;

[0032] The inhibitor is composed of 3,4-dimethylpyrazole phosphate (DMPP) and a nano-carbon solution. The nano-carbon solution is a mixture of nano-carbon and water, with a concentration of 0.0652 mg / mL. The mass ratio of nano-carbon to 3,4-dimethylpyrazole phosphate (DMPP) in the nano-carbon 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 nano-carbon in the nano-carbon solution is 0.75% of the nitrogen content in the nitrogen fertilizer.

[0033] Experimental Example: Microcosm Culture Experiment

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

[0035] The specific steps are as follows:

[0036] The soil moisture content was adjusted to 40% of field capacity, i.e., 14.0 mL of deionized water was added to every 100 g of dry soil. The soil was then incubated at 25°C in the dark for 10 days. 120 g of the pre-cultured soil was transferred to a 1 L glass bottle. Urea was then applied to the pre-cultured soil at a dosage of 100 μg urea-N·g. -1 DWS (Dose-Weighted Water), i.e., 26.08 mg added to each bottle, followed by the inhibitors from treatment groups 1-4. At this point, the soil moisture content was 60% of field capacity. The plants were incubated at 25℃ in the dark for 28 days, with ventilation every 5 min every 3 days under a partially covered plastic wrap. Gas samples were taken on days 0, 1, 3, 7, 14, 21, and 28, and the N2O emission flux was measured using a gas chromatograph. Finally, the total N2O emissions for each treatment were calculated, and the results are shown in Table 1.

[0037] The formula for calculating total N2O emissions is as follows:

[0038]

[0039] In the formula, E represents the total N2O emissions, expressed in kg·hm². -2 F represents gas flux, with units of μgN₂O₻N·m⁻¹. -2 ·h -1 n is the total number of gas measurements, i is the sampling time, (t i+1 -t i () represents the number of days between two gas measurements.

[0040] This experiment consisted of four treatment groups, with three replicates in each group, as detailed below:

[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 inhibitor, wherein the preparation method and concentration of nanocarbon solution are the same as in Example 1;

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

[0045] Ensure that the amount of inhibitor applied is consistent across all treatment groups.

[0046] Table 1. N2O emissions from different treatment groups

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

[0048] As shown in Table 1, the N2O emission treated by CK was 0.593 kg hm. -2 The DMPP treatment capacity for N2O emissions is 0.360 kg / hm. -2 The N2O emission reduction from nano-carbon treatment is 0.423 kg / hm. -2 The N2O emission reduction achieved by DMPP + nano-carbon treatment is 0.171 kg hm. -2 Compared to the control group, using DMPP as the only inhibitor reduced N2O emissions by 0.233 kg·hm². -2 Using only nano-carbon as an inhibitor, N2O emissions were reduced by 0.170 kg·hm². -2 The present invention uses a combination of DMPP and nano-carbon as an inhibitor, which reduces N2O emissions by 0.422 kg·hm. -2Therefore, it can be seen that the present invention uses a combination of 3,4-dimethylpyrazole phosphate (DMPP) and nano-carbon solution as an inhibitor, which has a synergistic effect in reducing the total N2O emissions in soil.

[0049] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method suitable for reducing N2O emission from soil after straw returning in medium-weak acid soil, characterized in that, Includes the following steps: The soil in which all straw is pulverized and returned to the field is considered as a slightly acidic soil. After pre-cultivation, nitrogen fertilizer is applied to the pre-cultivated slightly acidic soil, followed by the application of inhibitors. The soil is then cultivated at 25°C in the dark for 28 days to reduce N2O emissions from the slightly acidic soil. The inhibitor includes a nitrification inhibitor and a nano-carbon solution. The nitrification inhibitor is 3,4-dimethylpyrazole phosphate. The nano-carbon solution is a mixture of nano-carbon and water, with a concentration of 0.0652 mg / mL. The mass ratio of nano-carbon to 3,4-dimethylpyrazole phosphate in the nano-carbon solution is 1:

2. The application amount of 3,4-dimethylpyrazole phosphate is 1.5% of the nitrogen content in the nitrogen fertilizer, and the application amount of nano-carbon in the nano-carbon solution is 0.75% of the nitrogen content in the nitrogen fertilizer.

2. The method for reducing N2O emission from soil after straw returning in middle-weak acid soil according to claim 1, characterized in that, The pre-cultivation process for moderately acidic soil is as follows: After sieving the slightly acidic soil, the soil moisture content was adjusted to 40% of the field capacity, and the soil was placed in a dark environment at 25°C for 10 days.

3. The method for reducing N2O emission from soil after straw returning in middle-weak acid soil according to claim 1, characterized in that, The nitrogen fertilizer is urea, and the application amount of the nitrogen fertilizer is 100 μg urea-N•g -1 d.w.s.

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