A method for promoting methane uptake in a leymus chinensis grassland

Abstract

The application discloses a method for promoting the absorption of methane in sheep grassland, and belongs to the field of environmental protection.The method is achieved by the following steps: applying nitrogen fertilizer to artificial sheep grassland in the growing season (June-September) to promote the absorption of methane in the grassland, so as to achieve the purpose of methane emission reduction.The nitrogen fertilizer added in the method is ammonium nitrate, the adding frequency is once a month, and the total dose is 100 kg N / hm 2 . Through the method, the total absorption amount of methane in the grassland in the growing season and the next spring freeze-thaw period is increased by more than 140% compared with the natural condition. The method is simple to operate and low in cost, and is helpful to the realization of the low-carbon target in the management process of artificial sheep grassland. In particular, in the next spring freeze-thaw period, the average value of the nitrogen application group is 7.1 mg m ‑2 , the average value of the nitrogen-free group is-5.0 mg m ‑2 , and the nitrogen application treatment increases the cumulative absorption amount of CH4 in the grassland soil in the spring freeze-thaw period by 240.4%.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection, specifically relating to a method for promoting methane absorption in sheepgrass meadows. Background Technology

[0002] Global warming is a challenge facing all of humanity. Methane (CH4), the second largest greenhouse gas globally after carbon dioxide (CO2), is even more reactive in the atmosphere than CO2. According to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), the global warming potential (or warming effect) of CH4 is 84 times that of CO2, and its 100-year level is 28 times that of CO2. Since the Industrial Revolution in 1750, human activities such as the burning of fossil fuels and minerals have led to a dramatic increase in emissions of greenhouse gases such as CH4, directly or indirectly affecting the global climate.

[0003] Grasslands are an important type of vegetation ecosystem on land, accounting for about 40% of the total area of ​​global terrestrial ecosystems. Their soil carbon storage accounts for 10% to 30% of the global total, and their plant carbon storage accounts for 10% of the global total. As a weak sink for CH4, grassland ecosystems are the main terrestrial ecosystems for balancing atmospheric greenhouse gases.

[0004] Fertilization is one of the management methods for artificial grasslands. Fertilization can alter the physical and chemical properties of the soil, increase soil organic matter, improve crop yield, and change the quantity, activity, and community structure of microorganisms. Studies have shown that fertilization has a significant impact on soil CH4 emissions and absorption. Fertilization mainly leads to changes in soil nutrients, which primarily affect the content of easily decomposable organic matter in the soil, and influence the production and oxidation processes of soil CH4 by affecting the utilization of substrates by methanogenic bacteria for methane production and consumption.

[0005] Currently, greenhouse gas emission reduction in grassland ecosystems largely relies on plant CO2 absorption. However, studies have shown that freeze-thaw cycles disrupt soil aggregates and promote the release of reactive organic carbon, thereby contributing to soil CO2 emissions to some extent. This indicates that traditional CO2 emission reduction measures are not suitable for the climatic characteristics of freeze-thaw regions.

[0006] Therefore, in order to solve the above problems, the present invention changes the approach to greenhouse gas emission reduction by focusing on the relationship between grassland and CH4 flux. By adding nitrogen fertilizer during the growing season, the grassland can be encouraged to absorb methane to the maximum extent, thereby achieving the goal of methane emission reduction. Summary of the Invention

[0007] The purpose of this invention is to address the methane emission problem in sheepgrass grasslands. This invention provides a method to promote methane absorption in sheepgrass grasslands in order to achieve the goal of methane emission reduction.

[0008] A method to promote methane uptake in Leymus chinensis grassland involves applying a total amount of 90-110 kg N / hm² during the Leymus chinensis growing season. 2 Apply nitrogen fertilizer in a proportional manner;

[0009] The aforementioned sheepgrass grassland, at 100 kg N / hm 2

[0010] The nitrogen fertilizer mentioned is ammonium nitrate; it is applied in stages during the growth period of sheepgrass, once a month.

[0011] The time period for promoting methane absorption in sheepgrass grassland is the spring freeze-thaw period of the following year after nitrogen fertilizer is applied.

[0012] The aforementioned spring freeze-thaw period begins when the soil temperature exceeds 0°C for three consecutive days and continues until complete thawing.

[0013] This invention provides a method for promoting methane absorption in Leymus chinensis grasslands, belonging to the field of environmental protection. The method involves the following steps: applying nitrogen fertilizer to artificial Leymus chinensis grasslands during the growing season (June-September) to promote methane absorption and achieve methane emission reduction. The nitrogen fertilizer used is ammonium nitrate, applied monthly at a total dosage of 100 kg N / hm². 2 Using this method, the total methane uptake of grassland during the growing season and the following spring freeze-thaw period increased by more than 140% compared to natural conditions. This method is simple to operate, low in cost, and helps achieve low-carbon goals in the management of artificial sheepgrass grasslands.

[0014] In particular, the average nitrogen application rate for the group that applied nitrogen during the spring freeze-thaw period of the following year (2022) was 7.1 mg m -2 The average value of the group without nitrogen application was -5.0 mg m -2 Nitrogen application increased the cumulative CH4 uptake in grassland soil during the spring freeze-thaw period by 240.4%.

[0015] The beneficial effects of this invention are:

[0016] This invention comprehensively considers the nutrient requirements of Leymus chinensis under different water conditions, soil fertility, and fertilizer effects. By applying nitrogen supplementation, it identifies conditions that promote CH4 uptake during the growing season, maximizing CH4 uptake while ensuring basic grassland productivity. This method plays a crucial role in protecting the interests of herders and promoting CH4 emission reduction and sustainable grassland ecosystem development through scientific management. It also helps to comprehensively and accurately assess changes in grassland greenhouse gas emissions under varying nitrogen deposition conditions, and has significant scientific implications for understanding the nitrogen cycle's response to global climate change in the context of future global climate change. Attached Figure Description

[0017] Figure 1This is a comparison chart of the total cumulative CH4 uptake in grasslands under natural conditions using the technology of this invention;

[0018] Figure 2 This is a comparison chart of the CH4 flux of grassland during the growing season under natural conditions using the technology of this invention;

[0019] Figure 3 This is a comparison chart of the cumulative CH4 uptake, aboveground biomass, and pmoA gene abundance of the technology of this invention with those of grasslands under natural conditions during the growing season and spring freeze-thaw period. Detailed Implementation

[0020] The technical solution of the present invention will be described in detail below, but the scope of protection of the present invention is not limited to the embodiments described.

[0021] Example 1

[0022] The experimental site for this study was located at the Jilin Songnen Grassland Ecosystem National Field Scientific Observation and Research Station, situated in the western part of the Songnen Plain, a region with a typical continental monsoon climate. The climate of the Songnen Grassland varies with the seasons, with dry, windy springs and summers with little rainfall, and cold, snowless autumns and winters. Based on temperature data from 1953 to 2018, the average annual temperature in this region is 5.7°C, with average January temperatures ranging from -16°C to -26°C and average July temperatures ranging from 21.0°C to 23.0°C. The annual potential evaporation in this study area is approximately 1500–2000 mm, more than three times the total annual precipitation. The soil type in the study area is mainly saline-alkali soil, with a soil pH value between 8.0 and 9.0.

[0023] Due to the influence of soil and climate conditions, as well as human interference, a sheepgrass grassland has formed in this area, dominated by a grass community represented by sheepgrass. Therefore, this experiment selected sheepgrass as the research object.

[0024] This experiment was conducted during the 2021 and 2022 growing seasons, and included a control and a nitrogen application treatment. Treatments were administered in June, July, August, and September. The nitrogen application rate was 100 kg N / hm². 2 The application frequency is once a month, and the nitrogen fertilizer is NH4NO3.

[0025] CH4 flux was collected using a closed-box method. The static box was made of stainless steel sheet, forming a cylindrical barrel with a sealed top and a hole at the top. A sampling valve containing a rubber gasket was installed at the hole. A hole was left on the side of the sampling barrel to insert an air thermometer probe, which was then sealed for measuring the temperature of the gas chamber.

[0026] Gas sampling was conducted weekly in 2021, and adjusted to bi-weekly sampling in 2022 based on the previous year's emission patterns. Sampling times were from 9:00 AM to 11:00 AM. Relevant indicators were calculated using the following formula.

[0027] Soil CH4 flux calculation formula:

[0028] ;

[0029] Where F is the CH4 flux (μg m -2 h -1 ρ is the density of CH4 under standard conditions, and h is the height of the collection box (m). The slope of CH4 concentration over time is given, and T is the air temperature (°C) inside the chamber during sampling.

[0030] Formula for calculating soil cumulative CH4 flux:

[0031] ;

[0032] Where F is the cumulative flux of CH4 (mg / m³) -2 ), x is the daily average CH4 flux, i is the i-th measurement, (t i+1 -t i () represents the number of days between two samplings.

[0033] The CH4 flux and cumulative uptake of Leymus chinensis during the growing season were compared under different experimental treatments, such as... Figure 2 (a) Figure 3 (a).

[0034] Among them, the average nitrogen application rate in the nitrogen application treatment group during the 2021 growing season was 45.1 mg m -2 The average value of the nitrogen-free treatment group was 27.3 mg m. -2 Nitrogen application increased the cumulative CH4 uptake in grassland soil during the growing season by 65.2%. The average value of the nitrogen-treated groups in the 2022 growing season was 50.3 mg / m³. -2 The average value of the nitrogen-free treatment group was 33.0 mg m. -2 Nitrogen application increased the cumulative CH4 uptake in grassland soil during the growing season by 52.5%. In both the 2021 and 2022 growing seasons, nitrogen application significantly promoted CH4 uptake (P<0.01).

[0035] The cumulative CH4 uptake of Leymus chinensis under different treatments during the freeze-thaw period in the following spring (2022) was compared, such as... Figure 3 (b).

[0036] The spring freeze-thaw period is defined based on local soil temperature changes. The spring freeze-thaw period begins when the highest soil temperature exceeds 0°C for three consecutive days. The seasonal freeze-thaw period is defined as from the end of February to mid-April.

[0037] Experiments showed that during the freeze-thaw period in spring 2022, the cumulative CH4 uptake in the nitrogen-treated group was significantly higher than that in the non-nitrogen-treated group (P<0.01). The average uptake in the nitrogen-treated group was 7.1 mg m³. -2 The average value of the group without nitrogen application was -5.0 mg m -2 Nitrogen application increased the cumulative CH4 uptake in grassland soil during the spring freeze-thaw period by 240.4%.

[0038] The aboveground biomass of sheepgrass under different treatments during the growing season in 2021 and 2022 was compared. Figure 3 (c).

[0039] The experiment showed that there was no significant difference in the aboveground biomass of sheepgrass in the growing seasons of 2021 and 2022 under different treatments (P>0.05).

[0040] Among them, the average aboveground biomass of sheepgrass in the nitrogen-free group during the 2021 growing season was 36.4 g / kg. -1 The nitrogen application group used 39.1 grams of potting mix. -1 The average aboveground biomass of sheepgrass in the nitrogen-free group during the 2022 growing season was 36.0 g / kg. -1 The nitrogen application group used 36.6 grams per pot. -1 .

[0041] The abundance of soil methane monooxygenase (pmoA) genes under different treatments in 2022 was compared, such as... Figure 3 (d).

[0042] The average value of the group without nitrogen application was 3.6 × 10⁻⁶. 6 g -1 The average value of the nitrogen application group was 4.8 × 10⁻⁶. 6 g -1 Experiments showed that, during the freeze-thaw period in spring 2022, the cumulative CH4 uptake in the nitrogen-treated group was significantly higher than that in the non-nitrogen-treated group (P<0.01), and the nitrogen treatment significantly increased the number of soil methanogens (pmoA) by 25.3%.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can be arbitrarily combined without departing from the technical principles of the present invention.

Claims

1. A method for promoting methane absorption in sheepgrass meadows, characterized in that: During the growing season of Leymus chinensis, the total amount should be 90-110 kg N / hm². 2 Apply nitrogen fertilizer in a proportional manner; The nitrogen fertilizer mentioned is ammonium nitrate; The nitrogen fertilizer is applied in stages, once a month. The time period for promoting methane absorption in sheepgrass grassland is the spring freeze-thaw period of the following year after nitrogen fertilizer is applied. The aforementioned spring freeze-thaw period begins when the soil temperature exceeds 0°C for three consecutive days and continues until complete thawing.

Images