冬作季节土壤水分状况对稻田CH_4排放的影响

温室盆栽试验表明，冬作季节土壤持续淹水处理（淹水）稻田平均ＣＨ４ 排放通量显著高于干燥处理（干燥），前者是后者的５．５８ 倍（１９９６ 年）和４．１６ 倍（１９９７ 年）。冬作季节土壤水分状况明显影响土壤Ｅｈ 和ＣＨ４ 排放的季节变化。淹水处理土壤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），而干燥处理水稻移栽４２ ｄ 后土壤Ｅｈ 才降为负值，在此期间几乎没有ＣＨ４ 排放。

Effect of Soil Water Regime in Winter Cropping On CH_4 Fluxes From Rice Field.

A pot experiment in greenhouse was carried out showing that mean CH 4 flux of flooding treatment was 5.58 (1996) and 4.16 (1997) times higher than that of dry treatment. Soil regime in winter cropping also markedly affected seasonal variation patterns of soil Eh and CH 4 fluxes. Soil Eh of the flooding treatment was in the active range of methanogenic bacteria during the whole rice growing season, so CH 4 emission occurred throughout the entire period (except for the days when the soil was exposed for drying). For the soil Eh of the dry treatment, however, it took 42 days after rice transplanting to drop down to negative value and CH 4 emission was very low during the period.