Effects And Applications Of Soil Greenhouse Gas Emission Reduction Under Different Cultivation Patterns Of Winter Wheat In Guanzhong Area

China’s agricultural carbon emissions accounted for 16%～17%of the total national emissions,significantly higher than the world average level,and the arable land in the arid region accounted for 56%of the total arable land in the country.Therefore,under the background of carbon neutrality,how to achieve green agricultural transformation and high-quality development in the arid region and reduce agricultural greenhouse gas emissions in the arid region will play an important role in promoting sustainable agricultural development and achieving carbon neutrality in 2060.Agricultural ecosystems in arid regions are extremely fragile and of low stability.Farmland management measures have a significant impact on greenhouse gas emissions and crop yield of farmland ecosystems.Especially,farmland cultivation mode makes soil hydrothermal environment in arid regions significantly different.As a result,greenhouse gases（carbon dioxide（CO₂）,methane（CH₄）,nitrous oxide（N₂O））were significantly controlled by soil temperature,moisture and other environmental factors under different cultivation modes.However,most current studies focus on the improvement of crop yield and water and fertilizer utilization efficiency under different cultivation modes,while ignoring the influence of soil hydrothermal environment on the emission characteristics of CO₂,CH₄ and N₂O under different cultivation modes.In particular,the research on how to improve crop yield while reducing farmland greenhouse gas emission under different cultivation modes needs to be further carried out.Therefore,it is of great significance for sustainable agricultural development in arid regions and national agricultural carbon neutrality to explore the influence of different farmland cultivation modes on greenhouse gas emissions.In this study,the rain-fed winter wheat in dryland was taken as the research object,and six cultivation and simulation measures were set up,including traditional cultivation mode control（T）,straw mulching（SM）,film mulching（PM）,exposed ridge furrow（BRF）,straw mulching in furrow with film mulching（MRF）and green fertilizer rotation（GM）,by combining field positioning experiment observation and model simulation.To study the effects of different farmland cultivation patterns on greenhouse gas emissions.The experiments mainly included:to observe the emission fluxes of greenhouse gases CO₂,CH₄ and N₂O from winter wheat fields in Guanzhong Plain during 2021-2022;The changes of soil temperature and water content in different soil layers under different cultivation modes were studied.The content changes of available nitrogen,organic carbon and microbial biomass carbon and nitrogen in 0-10cm and 10-20cm soil layers were monitored.Life cycle assessment（LCA）was used to clarify the Net greenhouse effect（Net-GWP）and carbon footprint（CF）under different cultivation modes.DNDC model（De Nitrification-De Composition model）was used to simulate the Net-GWP under the six cultivation modes in the next 100 years,so as to clarify the feasibility of the emission reduction cultivation mode in the future application.The main research results are as follows:（1）Effects of different cultivation patterns on soil moisture and heat conditions in winter wheat fields.The soil moisture content of 0～10cm and 10～20cm soil layers in the six cultivation modes of winter wheat growth period showed the order of MRF>SM>PM>BRF>T>GM.Compared with the traditional cultivation mode,green fertilizer rotation reduced soil moisture content,while the other four cultivation modes increased soil moisture content.The straw pattern in the furrow on the ridge has the greatest influence on the water content.Compared with the traditional culture,the straw in ridge mulching trench has a great influence on soil temperature.The straw in ridge mulching trench can improve the soil water temperature condition.This mode integrates the advantages of mulching and mulching mode.（2）Soil organic carbon content in winter wheat field was affected by different cultivation modes.The results showed that the effects of different cultivation modes on soil organic carbon content of winter wheat field were as follows:SM>MRF>GM>PM>BRF>T.The results showed that straw mulching and straw mulching in ridge had a significant effect on soil organic carbon content.GM>PM>SM>BRF>T>MRF showed the effects of different cultivation modes on the content of soil available nitrogen in winter wheat field.The cultivation mode of straw in furrow covered with film effectively reduced the residue of soil available nitrogen,and promoted the absorption of nitrate nitrogen and ammonium nitrogen by winter wheat.SM,PM,BRF,MRF and GM cultivation modes all promoted the microbial biomass C and N content of winter wheat at jointing stage.Under the six cultivation modes,the microbial biomass C and N ratio of farmland soil at jointing stage was 1～15,and the microbial biomass C and N ratio of SM,PM and MRF was low,and the potential of nitrogen release through microbial biomass turnover was high.（3）Greenhouse gas emission characteristics of winter wheat fields were significantly affected by different cultivation patterns.The cumulative emission fluxes of CO₂,CH₄and N₂O in soil during the whole growth period of winter wheat showed significant period variation characteristics.The cumulative emission fluxes of CO₂ in farmland during the whole growth period of winter wheat were GM>PM>SM>BRF>T>MRF.The cumulative absorption flux of CH₄ is BRF>GM>SM>T>PM>MRF.The cumulative emission flux of N₂O is GM>SM>BRF>MRF>PM>T.（4）Different cultivation patterns significantly affected the intensity of net greenhouse effect and carbon footprint of farmland soil.The net greenhouse effect of the six cultivation modes was GM>MRF>SM>BRF>PM>T.The carbon footprint CF size was jointly determined by Net-GWP and winter wheat yield,SM>GM>BRF>T>PM>MRF.The straw in the furrow had a lower field carbon footprint of121.541 kg·CO₂eq·kg^-1.Combined with the simulation of 100 years of rain-fed winter wheat field in dryland by DNDC model,the model of straw in furrow covered with film had the lowest carbon footprint per unit seed yield and had the most significant effect on greenhouse gas emission reduction in farmland.In this study,wheat,a long-term crop in a rain-maintained agricultural environment in a typical arid region,was selected as the research object.By combining field positioning experiment observation with model simulation,the optimal wheat production mode in the experimental area was established by analyzing soil physical and chemical properties,greenhouse gas emission,net greenhouse effect and carbon footprint under different cultivation modes.In order to provide experimental basis for selecting green and low carbon wheat production mode in arid region.