不同秸秆还田模式对稻麦两熟农田稻季甲烷和氧化亚氮排放的影响

摘要

为了探讨不同秸秆还田模式下稻麦两熟农田稻季甲烷( CH4)和氧化亚氮( N2 O)的排放规律,为评估该地区温室气体排放量与发展循环农业提供依据,在江苏省苏州市稻麦两熟农田进行了6年的田间定位试验,采用静态箱-气相色谱法开展了不同秸秆还田模式下水稻生长季田间甲烷和氧化亚氮排放监测试验,研究设计了稻麦季秸秆均不还田(CK)、麦季稻秸还田(R)、稻季麦秸还田(W)和稻麦季秸秆均还田(RW)4种秸秆还田模式。结果表明：不同秸秆还田模式对稻季CH4和N2 O排放、总增温潜势( GWP)及单位产量的GWP有极显著影响,CH4稻季总排放量表现为RW(233.04 kg/hm2)>W(197.99 kg/hm2)>R(122.14 kg/hm2)>CK(97.07 kg/hm2),N2O稻季总排放量的顺序是R>W>RW>CK,依次为4.74 kg/hm2、2.66 kg/hm2、2.14 kg/hm2和1.07 kg/hm2。 RW处理水稻产量(10.54 t/hm2)和R处理(10.36 t/hm2)较秸秆不还田对照显著增产,而秸秆还田处理( R、W和RW)的GWP以及单位产量的GWP均显著高于秸秆不还田对照。说明,秸秆还田增加了稻季CH4和N2 O排放,小麦秸秆还田是增加稻季CH4排放的重要原因。%Although straw returning of rice is a primary way of straw utilization, excessively returning not only affected the crop growth but also went against the eco-logical environmental protection of farmland. The objective of the study was to estimate the flux of methane ( CH4 ) and nitrous oxide ( N2 O) emission in a rice-wheat double cropping system influenced by different patterns of straw returning to field. A six-year field experiment was conduc-ted in Suzhou, Jiangsu province, and straw returnings to field were set as rice straw returning ( R) , wheat straw returning ( W) , both rice and wheat straw returning ( RW) and no straw returning ( CK) treatments. The methan and nitrous oxide emissions were measured by static chamber-gas chromato-graphic technique. The results showed that total CH4 and N2 O emissions, global warming potential ( GWP) and GWP per unit yield were significantly influenced by patterns of straw returning to field. Total CH4 emissions followed the order of RW (233. 04 kg/hm2) > W (197. 99 kg/hm2) > R (122. 14 kg/hm2) > CK (97. 07 kg/hm2). Total N2O emissions were R > W > RW > CK. Compared with CK, RW (10. 54 t/hm2 ) and R (10. 36 t/hm2 ) significantly increased grain yield. Seasonal global warming potentials ( GWPs) of CH4 and N2 O and GWPs per unit grain yield were higher in R, W and RW plots than those in CK plots. These results indicate that straw returning to field boosted CH4 and N2 O emissions and wheat straw returning to field played a key role in increasing CH4 emission.