免耕和秸秆覆盖对农田土壤温室气体排放的影响

农业土壤是重要的温室气体排放源,各种农业措施对温室气体排放产生重要的影响。免耕和秸秆覆盖作为两种重要的保护性耕作措施正在被越来越广泛的应用,但是其对土壤温室气体排放的影响还不明确,结果存在分歧。通过对免耕和秸秆覆盖措施下农田三种主要的温室气体（CO2、CH4和N2O）排放的相关研究进行对比分析,探讨两种保护性农业措施对温室气体排放的影响。研究表明,免耕减少土壤干扰,增加团聚体的稳定性,有利于难分解碳的形成,减少土壤CO2排放;与常规耕作相比,免耕有利于CH4氧化,增强甲烷氧化菌活性,降低CH4排放;免耕对N2O排放的影响与气候类型和土壤性质有密切的相关关系,在干燥的气候条件下,免耕增加通气条件差的土壤的N2O排放,对通气好的土壤影响不大。而在湿润的气候条件下,不同的土壤性质结论不一致。秸秆覆盖增加土壤CO2排放,并随着秸秆覆盖量的增加而增大;秸秆覆盖对CH4排放的影响有很大的不确定性,与覆盖方式和覆盖秸秆性质有密切联系;大部分研究认为秸秆覆盖增加N2O排放,但也有研究认为秸秆覆盖对N2O排放无影响或降低N2O排放量,秸秆覆盖对N2O排放机理复杂,需要进一步研究。通过综述发现随着保护性农业措施的推广,大量的研究集中在其对作物产量、土壤水分利用率、土壤性质等方面的研究;而保护性农业措施对温室气体排放的研究相对较少,特别是对三种温室气体的综合影响研究并不多见。因此,需结合不同土地类型,开展不同气候类型下免耕和秸秆覆盖对三种主要温室气体排放影响的综合研究,预测增温潜势,为不同气候带保护性农业措施下温室气体排放提供基础数据,并为制定合理的耕作和秸秆覆盖措施提供理论支持。运用同位素示踪等新技术明确秸秆覆盖对温室气体排放的直接和间接贡献率,结合不同研究区?

Effects of no-till and straw mulch on greenhouse gas emission from farmland： A review

Agriculture soil is an important source of greenhouse gas emissions （GHGs）, and agricultural management strategies would have a significant influence on GHGs. As two important conservation agricultural strategies, no-till and straw mulch are getting an increasingly wide use in agricultural activities. However, the effect of no-till and straw mulch on GHGs is not clear, and the results from the previous studies are inconsistent. In this study, three important GHGs （CO2, CH4 and N2O） under no-till and straw mulch management were analyzed through analyzing the results from previous literatures to investigate the effect of no-till and straw mulch on GHGs compared with conventional tillage. The results indicated that compared with conventional tillage, no-till reduced soil disturbance, increased the stability of soil aggregates, favored for formation of stable carbon, and reduced CO2 emissions. No-till was benefit for CH4 oxidation, increased the activity of methane-oxidizing bacteria, and reduced CH4 emission. The effect of no-till treatment on N2O emission was highly correlated with climate conditions and soil properties. In dry climate condition, no-till increased N2O emission in poorly-aerated soil, but did not obviously impact N2O emission in good-aerated soil. In wet climate condition, the impacts of no-till on N2Oemission were different under different soil properties. Straw mulch generally increased soil CO2 emission, and it increased with the increase of straw mulch amount. The impact of straw mulch on CH4 emission was highly uncertain, but closely related with the mulching methods and the straw properties. Most researches indicated that straw mulch increased N2O emission, while there were also some research results of no effect or reducing N2O emission. The mechanism of the impact of straw mulch on N2O emission is complex and needs a further research. In the end, research prospect in this field was pointed out. As the promotion of conservation agriculture, many studies were concentrated on crop yield