太湖地区水稻季氮肥的作物回收和损失研究

在太湖地区水稻土上，采用田间微区15N示踪试验研究了不同氮磷肥配合下水稻季氮肥去向以及残留肥料氮在麦季的吸收利用。结果表明，水稻当季作物对肥料氮的回收率为29%～39%，土壤残留肥料氮的后效很低，后季冬小麦仅利用土壤残留肥料氮的2.4%～5.2%。经过连续两个稻麦轮作，0—60cm土壤中残留肥料氮占施氮量的11%～13%，绝大多数在0—20 cm表层土中。水稻季施用的肥料氮向耕层以下移动很少，20—60 cm土层中累积肥料氮仅占施氮量的0.6%～1.1%，主要发生在小麦季及水稻泡田时期，肥料氮损失占施氮量的47～54%，氨挥发和硝化反硝化气态损失是主要途径。高氮和高磷处理没有增加作物产量和氮肥利用率，过量施氮或施磷无益于作物增产和氮肥吸收利用。

Recovery by crop and loss of nitrogen fertilizer applied in rice season in Taihu Lake region

Field micro-plot ¹⁵N labeled fertilizer experiment was conducted to investigate the fate of fertilizer N applied in rice season and the residual fertilizer N recovery in the succeeding wheat season in paddy fields in Taihu Lake region. Data showed that 29%–39% of the labeled fertilizer N was present in above-ground rice crop at harvest. Turnover rate of the residual fertilizer N by the succeeding crop was low and only 2.4%–5.2% of the residual soil N was present in the wheat crop. After two rice-wheat rotations, 11%–13% of applied labeled N remained in 0-60 cm soil (mostly in the 0-20 cm soil); leaching of labeled urea applied in rice season was little (only 0.6%–1.1% of the applied N accumulated in 20-60 cm soil), and the leaching of fertilizer N occurred in wheat season and the beginning flooding period of the next rice season; 47%–54% of applied fertilizer N was lost and ammonia emission and nitrification-denitrification were the main pathways. High N and high P inputs did not lead to the increase in grain yield and plant N use efficiency.