不同水分管理模式下水稻土氮素形态转化与N2O释放的关系

在实验室培养条件下,对稻田土壤在4种水分管理模式下施用尿素后N素形态转化和N2O的释放情况进行测定。结果表明,N2O的释放峰值与NH4+-N浓度峰值同时出现,即尿素迅速水解为NH4+-N的同时N2O就大量释放。且不同水分管理模式都迅速达到N2O释放的高峰,但不同模式的峰值存在明显差异,其顺序为:干湿交替>临界饱和水>淹水管理>旱作管理。研究结果还表明,NO2--N浓度在第7天达到峰值时并没有出现相应的N2O释放峰,这可能与土壤的较高pH有关。60%WFPS处理以及干湿交替培养的落干期NO3--N浓度会持续增加,并随着NO3--N浓度峰值的出现,N2O的释放也出现一个峰值。

Relationship of N-form translation and N2O emission in paddy soils under different water regime

The Nitrogen form and N2O emission of paddy soil under 4 water regime (Flooding continuely-110%WFPS (F), upland simulation-60%WFPS (U), near saturation water-95%WFPS (SW) and alternation between F and U (ALT)) was determined at laboratory scale. The results showed that N2O emitted rapidly with the Urea-N hydrolyze. The soil NH4+-N and N2O emission reached a peak value in all treatment after urea-N application 3 days later. However, The N2O emission peak value was quite different at different water regime treatment. The order of the N2O emission was: ALT SW > Flooding > upland. The result also showed that the N2O emission did not show a peak value when the NO2--N arrived peak value after seven days from the day of application. The NO3--N concentration increased continually at upland treatment and the dry period of ALT treatment until 11 days it arrived a peak value. The N2O also appeared a small peak with the NO3--N peak present.