稻草还田下非稻季持续淹水对稻季CH4和CO2排放的影响

摘要

稻草还田和非稻季持续淹水是我国最重要的稻田管理方式之一,此种管理方式下稻田碳排放并不清楚.本研究以江汉平原中稻-冬闲制度为对象,探讨稻草还田耦合非稻季持续淹水对稻季碳排放的影响,为准确评估稻田温室气体排放提供数据支撑和理论支持.结果表明,在稻草秸秆全量覆盖还田下,非稻季自然排水比持续淹水显著降低稻季CH4累积排放量,稻季第一次排水晒田之前CH4排放占总排放量的80%以上;非稻季持续淹水使稻季CO2累积排放量比自然排水稍有降低,CO2排放主要集中在第一次排水晒田之后,占总排放量的60%左右.非稻季淹水降低稻季土壤NO-3-N、NH+4-N和DOC浓度以及10 cm土层土壤Eh值,但使乙酸浓度升高,这可能是稻草还田耦合非稻季淹水导致CH4排放量增加的主要原因.%Straw returning is a straw utilization pattern which is widely promoted in China. It can increase the soil organic carbon and fertility, but straw returning also increase the CH4 and CO2 emissions. The effects of continuous flooding in no rice growing season on CH4 and CO2 e-mission in rice season with straw returning is not clear. This study was conducted with two different water managements in no rice growing season, one was the middle rice- natural drainage(RD)and another was the middle rice- continuous flooding(RW). The aim was to inves-tigate the characteristic of CH4 and CO2 emission flux in rice season under different water management with straw returning, and to provide da-ta support for accurate assessment of paddy greenhouse gas emissions. The results showed that RD significantly reduced the CH4 accumulation emission flux in rice growing season compared with the RW, and 80%total CH4 emission flux in rice growing season was emission before the first drainage whether RD or RW. RW could cutdown the CO2 accumulation emission flux in rice growing season compared with RD, and about 60%total CO2 emission flux in rice growing season was emission after the first drainage whether RD or RW. RW reduced the soil NO-3- N, NH+4-N and DOC concentration in rice growing season, and decreased the Eh value at 10 cm soil layer, but increased the acetic acid concen-tration. This might be the main reason of increasing the CH4 accumulation emission flux from RD.