杨麦间作系统硝态氮淋失的原位研究

利用田间原位淋溶装置研究了杨麦间作系统中林分密度和施氮量对小麦田土壤60 cm深处硝态氮淋失浓度和淋失量及0～80 cm土层硝态氮分布特征的影响。施氮量设不施氮(N0,0 kg/hm2)、常规施氮(N140,140 kg/hm2)、减量施氮(N70,70 kg/hm2)、增量施氮(N210,210kg/hm2)4个处理。结果表明:对照地淋溶水量与降水呈显著正相关关系;杨麦间作系统能显著减少淋溶水量。土壤硝态氮淋溶量随施氮量的增加而上升,对照地60 cm处N210处理下硝态氮淋溶量最大,为13.89 kg/hm2。杨麦间作系统L1(2 m×5 m)小区距树0.5 m处淋溶量比对照麦地减少了60.27%;相同处理距树1.5 m处比对照地减少了50.11%,不同林分硝态氮淋失量不同,但差异不明显。分析认为,杨麦间作系统能有效减少硝态氮在土壤中的淋溶和累积,且存在明显的空间变异性。

Study on nitrate nitrogen leaching in poplar-wheat intercropping ecosystem by in situ analysis

By using in situ leaching device,a field experiment was conducted to study the nitrate leaching amount and density at 60 cm soil depth,nitrate accumulation in soil profile(0-80 cm) of poplar-wheat intercropping ecosystem.Four treatments were installed,no fertilization(N0,0 kg/hm2),conventional fertilization(N140,140 kg/hm2),reduced N application(N70,70 kg/hm2),increased N application(N210,210 kg/hm2).The results indicated a positive correlation between quantity of leachate water and precipitation,the poplar-wheat intercropping ecosystem can reduce the quantity of eluviate solution.The nitrate leaching loss increased according to the increasing N fertilization rate.In treatment spot N210,the nitrate nitrogen loss from N fertilization at 60 cm soil depth was the greatest(13.89 kg/hm2),it declined by 60.27 % and 50.11 % in poplar-wheat intercropping ecosystem away from the poplar row 0.5 m and 1.5 m,respectly.The nitrogen leaching and accumulation were significantly lower in poplar-wheat intercropping ecosystem,and variances of the distribution for soil nitrate nitrogen were significant.