秸秆还田条件下灌溉方式对双季稻产量及农田温室气体排放的影响

为研究秸秆还田条件下不同灌溉方式对双季稻生长及稻田温室气体排放的影响,以双季稻为对象,通过连续3年田间定位试验,系统分析了秸秆还田条件下不同灌溉方式对双季稻生长和稻田综合温室效应的影响。试验设置持续淹水(F)、中期烤田(F-D-F)和间歇灌溉(F-D-F-M)共3种处理。结果表明:与F处理相比,F-D-F和F-D-F-M处理早稻平均产量分别增加9.8%和2.7%,晚稻平均产量分别增加4.8%和2.0%,其中F-D-F早稻产量显著高于F-D-F-M处理。与F处理相比,F-D-F和F-D-F-M处理早稻平均每穗粒数分别增加12.5%和5.7%,晚稻平均每穗粒数分别增加9.7%和3.1%。在双季稻系统3年轮作周期中,F、F-D-F和F-D-F-M处理CH_4周年累积排放量范围分别为678.2~988.4、322.6~661.7 kg·hm~(-2)·a~(-1)和208.3~520.6 kg·hm~(-2)·a~(-1),N_2O周年累积排放量分别为5.86~12.64、4.25~11.24 kg N·hm~(-2)·a~(-1)和9.14~14.91 kg N·hm~(-2)·a~(-1)。与F处理相比,F-D-F和F-D-F-M处理全球增温潜势分别显著降低31.5%~44.9%和38.2%~53.4%,温室气体排放强度分别显著降低36.2%~48.7%和38.8%~54.6%。因此,在南方双季稻区,与持续淹水处理相比,秸秆还田条件下中期烤田和间歇灌溉处理都可以实现水稻高产和稻田温室气体减排的目标。

Effect of different irrigation methods on rice yield and greenhouse gas emissions under crop residue incorporation in double rice-cropping systems

As the main by-product of crop production, crop straw contains abundant organic matter, nitrogen, phosphorus, potassium, and other nutrients. As a popular management practice in double rice-cropping systems of China, straw incorporation can increase crop yield by improving soil physical and chemical properties and promoting soil quality and nutrient cycling. However, straw incorporation would increase greenhouse gas emissions from rice paddies; therefore, a feasible management practice should be sought to mitigate the global warming potential from CH₄ and N₂O emissions. Appropriate water management is an effective way to reduce greenhouse gas emissions, but the effect of different irrigation methods on rice yield and greenhouse gas emissions under crop residue incorporation is still unclear. A field experiment was conducted in 2013-2015 to determine the effect of water regimes on rice yield and greenhouse effect under crop residue incorporation in typical double rice-cropping systems. The three irrigation methods included continuous flooding(F), flooding-midseason drainage-reflooding(F-D-F), and flooding-midseason drainage-reflooding-moist intermittent irrigation(F-D-F-M) in the rice growing seasons. Rice straw was simultaneously chopped into 5 cm pieces by using a combine harvester. The results showed that, compared with that of the F plots, the grain yield in the F-D-F and F-D-F-M plots was increased by 9.8% and 2.7% in the early-rice season and by 4.8% and 2.0% in the late-rice season, respectively. The grain yield in the F-D-F plots was significantly higher than that in the F-D-F-M plots in the early-rice season. Compared with that of the F plots, the average spikelet number per panicle in the F-D-F and F-D-F-M plots was increased by 12.5% and 5.7% in the early-rice season and by 9.7% and 3.1% in the late-rice season, respectively. Across the three-year rotation cycle in the double rice-cropping system, the annual range of CH₄ emission in the F, F-D-F, and F-D-F-M plots was 678.2~988.4, 322.6~661.7 kg·hm^-2·a^-1, and 208.3~520.6 kg·hm^-2·a^-1, and that of N₂O emissions of the F, F-D-F, and F-D-F-M plots was 5.86~12.64, 4.25~11.24 kg N·hm^-2·a^-1, and 9.14~14.91 kg N·hm^-2·a^-1, respectively. Compared with that of the F plots, the global warming potential in the F-D-F and F-D-F-M plots was remarkably reduced by 31.5%~44.9% and 38.2%~53.4%, respectively. The greenhouse gas emission intensity in the F-D-F and F-D-F-M plots was remarkably reduced by 36.2%~48.7% and 38.8%~54.6%, respectively. Therefore, compared with continuous waterlogging, both of midseason drainage and intermittent irrigation can increase rice yield and mitigate greenhouse gas emissions under crop residue incorporation in the double rice-cropping system.