种稻土壤CH4排放规律的研究

通过盆栽试验研究了水稻生长期CH4排放的规律。结果表明，CH4排放存在明显的日变化，最大值出现在下午4点左右，最小值出现在凌晨4点左右。土壤温度的变化是导致CH4排放日变化的主要因素。水稻生长期CH4排放的季节变化受前茬季节作物种植及稻草还田时间的显著影响。前茬季节种植紫云英及休闲且水稻移栽前施用稻草处理在水稻生长初期即有大量CH4排放，且在水稻生长的前期、中期和后期分别出现3个CH4排放峰；前茬季节种植小麦和休闲且在前茬季节前施用稻草处理的，直至水稻生长的中期才有少量CH4排放。烤田期间CH4的排放峰值出现在土壤呈微于松软状态时；烤田至土壤干裂时，CH4排放通量降至零。

Study on Regularity of CH_4 Emission From Paddy Soil

A pot experiment was carried out to study the regularity of CH4 emission from paddy soil. The results showed that there existed obvious diurnal variations of CH4 fluxes. The maximum flux occurred at 4 p.m. or so, and the minimum flux occurred at about 4 a.m. Diurnal variations of CH4 fluxes were mainly influenced by soil temperature at o~10 cm depth. bvious seasonal variations of CH4 fluxes were observed during rice growth period, and crop planting and rice straw application time in previous crop season significantly affected the seasonal variation. A great deal of CH4 emitted to the atmosphere just after rice transplanting, and three emission peaks occurred on the 7th, 40th, 91st days respectively after rice transplanting for treatments with Astragalus sinicus or fallow (rice straw was applied just before rice transplanting) in previous crop season. However, for treatments with wheat or fallow (rice straw was applied before previous crop season) in previous crop season, there were almost no methane emissions until the middle stage of ricegrowing season. Soil drying stimulated the release of soil-entrapped CH4. A CH4 emission peak occurred soon after the soils fell dry when the soils was dry and soft. As soil drying continued, the soil began to crack and CH4 emissions decreased to nil.