冬作季节土地管理对水稻土CH4排放季节变化的影响

通过温室盆栽试验对水稻土CH₄ 排放的季节变化及冬作季节土地管理的影响进行了研究.结果表明,冬作季节种植紫云英、淹水休闲及干燥休闲但泡水前施用稻草处理泡水后30dCH₄ 排放量分别高达133d观测期总排放量的67.5%、35.5%及33.3%,且在泡水后第13天及水稻移栽后第 7、40、91天分别出现 4个CH₄ 排放高峰;而种植小麦和干燥休闲但冬作前施用稻草处理泡水后55dCH₄ 排放量才占观测期总排放量的6.74%和 0.27%,随后至水稻收获CH₄ 排放通量也不高.冬作季节土地管理引起的水稻生长期土壤Eh季节变化的差异是造成CH₄ 排放通量季节变化差异的主要原因.

Effect of land management in winter crop season on seasonal variations of CH4 emissions from rice paddy soils

A pot experiment in greenhouse was carried out to study seasonal variations of CH₄ fluxes from rice paddy soils and the effect of land management in winter crop season on the seasonal variations. The results showed that four emission peaks occurred respectively 13 days after flooding and 7, 40, 91 days after rice transplanting, and CH₄ emission amounts during the first 30 days after flooding accounted for as high as 67.5%, 35.5% and 33.3% of the total emission amounts during the observing period of 133days for treatments with dry fallow but rice straw being applied just before flooding, alfalfa, and flooded fallow in winter crop season. However, for treatments with dry fallow but rice straw being applied before winter crop cultivating and winter wheat in winter crop season, CH₄ emission amounts during the first 50 days after flooding just accounted for 0.27% and 6.74 of the total emission amounts during the observing period, and CH₄ fluxes thereafter were also very small. Difference in the seasonal variation patterns of soil Eh due to land management in winter crop season was the main reason why seasonal variation patterns of CH₄ fluxes from different treatments were different.