农田温室气体净排放研究进展

Research Progress of Net Emission of Farmland Greenhouse Gases

农业是温室气体排放的主要排放源之一,农业温室气体减排对全球温室气体排放具有重要贡献,研究农田温室气体净排放潜力亦具有重要现实意义。本文阐述了农田温室气体净排放的涵义,并归纳总结了耕作方式、施肥、水分管理、间套作等农业措施对农田土壤有机碳(SOC)含量、农田土壤N2O和CH4、农田生产物资的使用所造成的温室气体(主要为CO2、N2O和CH4)排放的影响,结果表明:保护性耕作总体能提高表层SOC含量,减少CH4排放,但减少农田土壤N2O排放的研究尚存在一定的争议,耕作方式亦影响投入,从而影响温室气体的排放;施肥(特别是配施)能提高SOC含量。施氮肥越多,N2O排放量越大,而CH4主要受有机物料的影响较大;水分对减少N2O和CH4排放有相反作用,需综合进行平衡管理;不同的作物品种、间套作模式或促进或减少温室气体排放。此外,本文指出了国外在该领域的研究注重从系统角度考虑农田温室气体排放,而国内的研究则非常少,提出我国农田温室气体净排放可作为未来研究的一个重点,并对未来研究内容进行了初步归纳总结。

Agriculture is one of the major sources of greenhouse gases（GHGs） emission.Reducing GHGs emission from agriculture contributes a lot to global GHGs mitigation.Therefore,the potential of net GHGs emission is a key issue for agriculture GHGs mitigation.This paper illustrates the meaning of net GHGs emission in farmland.Effective factors,such as tillage,fertilizer,water management,intercropping or interplanting and so on,are summarized to show how they impact on soil organic carbon,N_2O and CH_4 emission from soil,and GHGs（CO_2,N_2O and CH_4） emitted in the process of producing and using the input.Result shows that conservation tillage increases soil organic carbon（SOC） content in top-soil and reduces emissiom of CH_4 while having no definite effect on mitigating N_2O.Tillage also has influence on input,hence having an impact on GHGs emission.Fertilizer can increase SOC content and particularly works when used combining inorganic with organic fertilizer.There is a linear relationship between amount of N fertilizer and N_2O emission while CH_4 is mainly effected by organic matter in the soil.Water plays an opposite role in N_2O and CH_4 emission.Besides,species,intercropping and relay intercropping have no definite effect on mitigating GHGs.The paper points out that foreign studies focus on farmland GHGs emission from the perspective of system while few studies are done at home,and suggests that net emission of farmland GHGs in our country should be a focus of study.A preliminary summary is made as to the content of future study in this field.