松嫩平原不同秸秆还田方式下农田温室气体排放及碳足迹估算

Estimation of Greenhouse Gas Emission and Carbon Footprint of Farmland under Different Straw Returning Methods in Songnen Plain

明确松嫩平原不同秸秆还田方式下的温室气体排放和碳足迹特征,对于制订本地区固碳减排策略、发展低碳农业和保障农业可持续发展具有积极作用。该研究基于松嫩平原黑土秸秆还田定位试验,在大豆-玉米-玉米典型轮作模式下,2013—2015年监测不同秸秆还田方式下(秸秆不还田旋耕CK、秸秆深施还田DSR、秸秆覆盖免耕SC)农田N_(2)O和CH_(4)排放变化,利用生命周期法估算农资投入和田间操作引起的直接或间接碳排放量,分析碳足迹特征。结果表明,在松嫩平原大豆-玉米-玉米轮作模式下,秸秆深施还田和秸秆覆盖免耕不影响土壤N_(2)O和CH_(4)排放。土壤温室气体排放、氮肥生产、磷肥生产和田间耕作是影响农田碳足迹的主要贡献因子,占农田碳足迹总量的90%左右。2013—2015年秸秆覆盖免耕处理农田碳足迹最低,较秸秆不还田旋耕和秸秆深施还田处理分别降低4.5%和5.1%,原因是秸秆覆盖免耕措施减少机械燃油产生的碳排放。秸秆深施还田和秸秆覆盖免耕处理可以提高大豆和玉米产量,平均分别增产5.1%和5.5%。综合而言,在松嫩平原大豆-玉米-玉米轮作体系下,秸秆覆盖免耕可以降低农田碳足迹并可提高大豆、玉米产量,是较适宜的耕作方式。

Clarifying the characteristics of greenhouse gas emissions and carbon footprint under different straw returning modes in Songnen Plain plays a positive role in formulating carbon sequestration and emission reduction strategies in the region to develop lowcarbon agriculture and ensure the sustainable development of agriculture.Based on the field experiment of black soil straw returning in Songnen Plain,N_(2)O and CH_(4) emissions were monitored under typical soybean-maize-maize rotation mode from 2013 to 2015 under different straw returning modes(i.e.,rotary tillage without straw returning,CK;deep straw returning,DSR;and no-tillage with straw mulching,SC).Direct or indirect carbon emissions caused by agricultural investment and field operation were estimated by the life cycle method,and the characteristics of carbon footprint were analyzed.The results showed that under the soybean-maize-maize rotation mode in Songnen Plain,DSR and SC management practices did not affect soil N_(2)O and CH_(4) emissions.Soil greenhouse gas emissions,nitrogen fertilizer production,phosphorus fertilizer production,and field tillage were the main factors affecting farmland carbon footprint,accounting for about 90% of the total farmland carbon footprint.From 2013 to 2015,the carbon footprint of SC was the lowest,4.5% and 5.1% lower than that of DSR and CK,respectively.The reason was that SC could reduce carbon emissions from mechanical fuel.On average,DSR and SC could increase soybean and maize yields by 5.1% and 5.5%,respectively.In summary,under the soybean-maize-maize rotation system in Songnen Plain,no-tillage with straw mulching can reduce the carbon footprint of farmland and improve the yield of soybean and maize,and thus is a suitable tillage method.