Study On Carbon Footprint Of Crop And Greenhouse Gas Emission Reduction Potential Of Chemical Fertilizer Reduction In Rice Field

Since the 21st century,the agricultural and rural economy has developed rapidly,in China,increasing grain production and farmers'income,and chemical fertilizers have a significant effect on grain production.However,with the increase in the amount of fertilization,agricultural non-point source pollution as a negative concomitant product of agricultural production,its shackles for agricultural sustainable development have become increasingly prominent,which has attracted great attention from countries around the world.The methane gas emitted from rice fields in China accounts for about29%of the world's total,and the methane gas generated during rice cultivation accounts for about 10%-20%of methane in the atmosphere.N₂O emissions from agricultural activities can reach 90%of the total emissions,and nitrogen fertilizer application is the main reason for N₂O production.This study takes rice and rape in Ezhou City as the research object,calculates the carbon footprint of rice field crop production through the carbon footprint model based on life cycle assessment,quantifies the greenhouse gas emissions of various agricultural inputs and contributes to the carbon footprint,and explores the rotation system and fertilizer application on greenhouse gas emissions during crop production.Secondly,the rationality of fertilization in the rice field of Ezhou city was evaluated,and on this basis,different nitrogen application scenarios were set up to explore the nitrogen surplus of rice crops in different scenarios and estimate the potential of greenhouse gas emission reduction.It can provide theoretical and practical reference for reducing greenhouse gas emission of farmland on the premise of ensuring output,and has important reference value for sustainable development of agriculture and construction of ecological civilization in China.The main conclusions are as follows:?1?According to the calculation of the carbon footprint of rice field crops,the land use carbon footprint of rice is higher than that of rape.From the perspective of crop output carbon footprint,the carbon footprint per unit yield of rice field crops is from high to low in order of rape>early rice>late rice>Medium rice.The spatial variability of the carbon yield per unit area and area of the four crops is not large,and the high-value areas are concentrated in the central part,which decreases from the central part to the surroundings.At the same time,the use of oil and rice rotation system can significantly reduce the carbon footprint per unit yield of rice,and nitrogen fertilizer is the main contributor to the carbon footprint of rice field crop production.Therefore,reducing the amount of nitrogen fertilizer applied and increasing the utilization rate are particularly important for reducing greenhouse gas emissions and mitigating climate change.?2?The evaluation of the application of chemical fertilizers shows that all samples of rapeseed N,P,and K fertilizers are in an excessive application state,and the application of chemical fertilizers for rape and even economic crops must be strictly controlled.The application of nitrogen fertilizer in rice is in an excessive application state,but the application amount of phosphate fertilizer and potassium fertilizer is insufficient,and the phenomenon of diazo fertilizer and light phosphorus and potassium fertilizer still exist.It is necessary to reduce the application of nitrogen fertilizer,increase the application of phosphate fertilizer and potassium fertilizer,optimize the fertilization structure on a regional scale,and reduce greenhouse gas emissions.?3?In terms of greenhouse gas emission reduction:under the conditions of 130 kg/ha,135 kg/ha and 140 kg/ha nitrogen application,the total greenhouse gas emission reduction potential brought by the reduction of rice total nitrogen in Ezhou city is 28.21Gg CO₂-eq yr^-1,26.02 Gg CO₂-eq yr^-1 and 23.83 Gg CO₂-eq yr^-1.From the perspective of potential estimation results,optimizing the application of nitrogen fertilizers can bring about greater crop greenhouse gas emission reduction potential,it is necessary to achieve effective allocation of nitrogen fertilizer resources to achieve its efficient use,and optimize the application of nitrogen fertilizers to maximize the reduction of nitrogen fertilizer applications and Greenhouse gas emissions from production.