前茬季节稻草还田时间对稻田CH_4排放的影响

通过盆栽试验研究了前茬季节稻草还田时间对稻田CH4排放的影响。与前茬季节前施用稻草(稻草早)相比,水稻移栽前施用稻草(稻草晚)的处理CH4排放量增加了3.04(1996年)和7.12(1997年)倍。稻草还田时间还明显影响CH4排放和土壤Eh的季节变化。稻草晚处理土壤Eh在整个水稻生长期皆处于适宜CH4产生的水平,所以整个水稻生长期皆有CH4排放(经历烤田后例外),而稻草早处理水稻移栽42d后土壤Eh才降为负值,在此期间几乎没有CH4排放。

Effect of Rice Straw Application Time in Previous Crop Season on CH4 Emission from Rice Paddy Field

A pot experiment was carried out to investigate the effect of rice straw application time in the previous crop season on CH4 emissions from rice field. Applying rice straw just before soil is flooded for rice transplanting (DFL) significantly enhanced CH4 flux by 3.04 times in 1996 and 7.12 times in 1997 compared with rice straw application just before the previous crop season (DFE). Seasonal variation of soil Eh and CH4 fluxes were also affected by rice straw application time in the previous crop season. Soil Eh of DFL treatment was in the active range of methanogenic bacteria during the whole rice-growing period, so CH4 emission occurred during the corresponding period (except being imposed by soil drying). While it took 42 days after rice transplanting when soil Eh of DFE treatment dropped to negative value and CH4 emission was very low during the period.