北京郊区冬小麦/夏玉米轮作体系中氮肥去向研究

Study on the fate of nitrogen fertilizer in winter wheat/summer maize rotation system in Beijing suburban

采用田间微区1 5N示踪试验研究了肥料氮在冬小麦、夏玉米当季和后茬的去向。结果表明 ,在供试土壤的肥力水平和生产条件下 ,N 12 0kg hm2 的施肥水平已经达到了较高产量 ,再增加氮肥施用量作物产量不再增加 ;其氮肥利用率和残留率均显著高于施氮量为N 36 0kg hm2 ,损失率则远低于后者 ;在一季作物生长后仍有 2 0 .9%～4 8 4 %肥料氮残留于 0～ 10 0cm土层 ,这些残留的肥料氮在后茬的利用率不足 8% ,至施肥后第 2或第 3茬作物 ,仍有部分肥料氮残留于土壤。在低施氮量时 ,肥料氮以NO-3 N残留的量很低 ,在高施氮量时 ,残留氮除以有机态、微生物态氮形式存在外 ,以NO-3 N形式存在的比例也很高 ;在氮素损失途径中 ,淋洗损失可能占有相当重要的地位。

The fate of nitrogen fertilizer in current crop and succession crops in winter wheat and summer maize rotation system were studied using field 15N micro-plot. The results showed that crop yield would not increase when nitrogen application rate was above N 120kg /hm2. The recovery rate and residual rate of N 120 kg /hm2 were much higher than those of N 360 kg /hm2, but losses rate of N 120 kg /hm2 was much lower than that of N 360 kg /hm2. The residual rate in 0-100cm was 20.9%-48.4% after current crop harvest, the recovery rate of residual nitrogen fertilizer was less than 8%. There still had some residue nitrogen fertilizer after second or third crop harvest; the residual nitrogen fertilizer had much proportion of NO- 3-N with high application rate. Nitrogen leaching may play an important role in nitrogen losses.