稻麦轮作下秸秆不同利用方式还田对稻田甲烷排放的影响

秸秆还田能够促进土壤固碳,但秸秆不同利用方式还田对稻麦轮作系统中甲烷(CH_4)排放影响的研究结果存在很大不确定性。本研究采用静态暗箱-气相色谱法对太湖地区秸秆不同利用方式一年还田下稻麦轮作系统中CH_4排放规律进行田间原位观测。试验共设置4个处理,分别是:常规处理(NPK,施用氮肥、磷肥、钾肥)、秸秆还田处理(NPK+S,氮肥、磷肥、钾肥与秸秆均匀混施)、秸秆生物炭处理(NPK+B,氮肥、磷肥、钾肥与黑炭均匀混施)和秸秆与腐熟剂配施处理(NPK+SDI,氮肥、磷肥、钾肥、秸秆与腐熟剂均匀混施)。不同处理下CH_4排放主要集中在水稻生长季。与NPK处理相比,NPK+S和NPK+SDI处理均增加CH_4排放,增幅分别为12.7%和20.9%,NPK+B处理减少了7.5%的CH_4排放。与NPK+S处理相比,NPK+SDI处理CH_4排放显著增加7.3%,而NPK+B处理CH_4排放显著降低17.9%。除NPK+B处理显著提高了作物产量,其他处理对产量并无显著影响。与NPK处理相比,NPK+S和NPK+SDI处理显著增加了单位产量甲烷排放,增幅分别为23.7%和18.4%,NPK+B处理降低了单位产量甲烷排放,幅度为19.9%。与NPK+S处理比较,NPK+SDI与NPK+B处理单位产量CH_4排放分别降低了4.3%和35.3%。结果说明秸秆配合腐熟剂还田或秸秆炭化还田可减轻由秸秆直接还田所带来的环境损害,且炭化还田的减排效果更佳。

Effects of different straw utilization methods on methane emissions from straw returning to paddy field in a rice-wheat rotation system

Straw returning to paddy field can promote soil carbon sequestration. There is great uncertainty about the effects of different straw utilization methods on methane(CH₄) emissions in rice-wheat rotation systems. Therefore, in situ static chamber-gas chromatography was used to observe the effects of different straw utilization methods on CH₄ emissions in a rice-wheat rotation system in the Taihu Lake region. Four treatments were set up in the experiment, including NPK(no straw plus fertilizer), NPK+S(wheat straw plus fertilizer), NPK+ B(straw-derived biochar plus fertilizer), and NPK+SDI(wheat straw with straw-decomposing microbial inoculants plus fertilizer). The CH₄ emissions under different treatments were mainly concentrated in the rice growing season. Compared with those of the NPK treatment, the NPK+S and NPK+SDI treatments increased the CH₄ emissions by 12.7% and 20.9%, respectively. Conversely, the NPK+B treatment decreased the CH₄ emissions by 7.5% compared with those of NPK. Compared with those of the NPK+S treatment, the CH₄ emissions in the NPK + SDI treatment significantly increased by 7.3%, whereas they decreased significantly by 17.9% in the NPK + B treatment. Biochar amendment(NPK+B) increased the grain yield, but other treatments did not. Compared with those of the NPK treatment, the NPK+S and NPK+SDI treatments significantly increased the yield-scaled methane emissions by 23.7% and 18.4%, respectively. In contrast, the NPK+ B treatment reduced the yield-scaled methane emissions by 19.9%. However, compared with those of the NPK+S treatment, both the NPK+ SDI and NPK + B treatments reduced the yield-scaled methane emissions by 4.3% and 35.3%, respectively. This study shows that coapplication of straw-decomposing microbial inoculants or application of straw-derived biochar are advantageous for reducing the environmental damage caused by straw returning to the field. In addition, the straw-derived biochar is better.