高肥力土壤冬小麦生长季肥料氮的去向研究 Ⅰ.冬小麦生长季肥料氮的去向

用15N示踪微区试验研究了常规灌溉和磷钾供应充足的条件下 ,冬小麦生育期肥料氮的去向。结果表明 ,冬小麦对肥料氮的吸收随施氮量的增加而显著增加 ,收获期冬小麦吸收肥料氮占总吸氮量的比例 45% ,吸收土壤氮占 55%。氮肥在整个作物 土壤体系中的回收率随施氮量的增加而显著减少 ,损失量增加。施氮量为 1 2 0kgN hm2 时 ,氮肥的损失率只有 9% ,在作物中的回收率为 45% ,在 0～ 1 0 0cm土壤中的残留率为 45% ;施氮量为 3 60kgN hm2 时 ,氮肥的损失率为 55% ,在作物中的回收率为2 3 % ,在 0～ 1 0 0cm土壤中的回收率为 2 1 %。残留肥料氮以NH4 N存在的数量很少 ,以NO3 N存在的数量随施氮量的增加而显著升高 ,低量施氮时以有机结合态存在的数量远远高于前两种形态 ,但在高量施氮条件下 ,以有机结合态存在的比例与NO3 N相当。肥料氮在 0～ 1 0 0cm土壤各层次中均有残留 ,随着深度的增加 ,残留量减少。从整体上看 ,肥料氮在收获时往下移动超出 1 0 0cm土体。

THE FATE OF NITROGEN FERTILIZE IN WINTER WHEAT GROWTH SEASON UNDER HIGH SOIL FERTILITY CONDITION

The fate of N fertilizer in winter wheat growth season was studied by 15 N mcro plot experiment under the conditions of conventional irrigation,adequate phosphorus and potassium supply.The results showed that the uptake of N by winter wheat sharply increased with the increase of nitrogen fertilizer rate.About 45% of total N uptake came from fertilizer N while the other 55% of total uptake from soil nitrogen at harvest.The recovery of fertilizer N in soil crop system sharply decreased with nitrogen fertilizer rate meanwhile loss rate increased respectively.When N rate is 120 kg N/ha(low N input),45 3% of fertilizer N was utilized by plant,45 3% remained in 0～100cm soil layer and only 9 4% not recovered by plant or in 0～100cm soil layer.However,when N rate was 360kgN/ha(high N input),23 2% was utilized by plant,20 9% remained in 0～100cm soil layer and 55 9% lost from plant soil system.Organic combining form was the main residual form of fertilizer N,NH 4 N form occupied a small percentage of total residual fertilizer N,and NO 3|N form increased rapidly with N rate.Traced fertilizer N was found in all 0～20,20～40,40～60,60～80 and 80～100cm soil layers,showing the movement of fertilizer N was at least below 100cm soil depth in winter wheat growth season.