秸秆填埋对水稻土表层水三氮动态的影响

采用盆栽试验方法研究了秸秆填埋对水稻土表层水三氮动态变化的影响。结果表明,施肥后,表层水总氮、铵态氮浓度迅速增加;随时间的推移,表层水氮素浓度下降较快。全氮在施肥后第1d达到峰值,铵态氮在施肥后第2d达到高峰,施肥后7d氮素含量基本与施肥前水平一致。秸秆还田有效地降低了水稻土表层水氮素含量,秸秆深埋处理有利于土壤对氮素吸收,使氮素的流失几率降低（DS处理比N处理表层水全氮浓度平均低10.2%）,流失潜能趋势大大减小。结果显示,施肥后1周内是控制表层水氮素流失的关键时期。

Effect of Straw Return with Landfill on Nitrogen Dynamics in Surface Water of Paddy Soil：An Outdoor Pot Experiment

An outdoor pot experiment was conducted to elucidate nitrogen dynamic characteristics in surface water of paddy soil with straw return with landfill. The results showed that the concentration of ammoniacal nitrogen （NH4^＋-N） and total nitrogen（ TN ） in surface water sharply increased, reached its peak at the 1st and 2nd day, respectively after compound fertilizer application, and subsequently, both declined rapidly. While the concentration of NO3^--N was very low, though, with a little raise at the 3rd day after compound fertilizer application. The treatment with straw return with surface application effectively decreased nitrogen concentration in surface water of paddy soil; while straw return as deep landfill reinforced the retention of nitrogen in paddy soil, and reduced nitrogen loss（ total nitrogen concentration of straw return with deep landfill in surface water was lower than that in no-straw treatment by 10.2% ）. Therefore, it might be reasonable that total nitrogen （TN） and ammonia nitrogen（ NH4^＋-N ） in 0-4 days after fertilizer application were taken as two key environmental monitoring indexes. The results also showed it would be important to control massive N loss from flooded paddy field within one week after fertilizer application.