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试验结果表明,太湖地区稻麦两熟制水稻产量与施氮量呈二次曲线关系,可用方程y=-0.00002x2+0.0095x+9.0384(r=0.993**)来描述,当施氮量为237.5kg/hm2时,可获得最高理论产量10.17t/hm2。不同生育时期植株的干物质积累量和氮素的积累量都随着施氮水平的增加而增大;氮肥表观利用率、生理利用率和农学利用率都随着施氮量的增加而降低;高肥处理432kg/hm2和540kg/hm2成熟期植株干物质积累量和氮素的积累量都较高,但因大量氮素滞留在茎鞘中而导致产量不高。土壤各层全氮含量随着深度的增加而减小;随着施氮量的增加,0～60cm各层土壤全氮含量增大,而60～100cm各层变化趋势不明显;但当施氮量较高(大于324kg/hm2)时,土壤氮素累积与下渗,土壤各层全氮含量提高,易造成氮肥奢侈吸收与氮肥污染。
The results showed that the yield and nitrogen application rate of rice and wheat double cropping rice in Taihu Lake area was quadratic curve and could be described by the equation y = -0.00002x2 + 0.0095x + 9.0384 (r = 0.993 **) 237.5kg / hm2, the maximum theoretical yield of 10.17t / hm2 can be obtained. The dry matter accumulation and nitrogen accumulation of plants at different growth stages both increased with the increasing of nitrogen application rate. Apparent utilization rate, physiological utilization rate and agronomic utilization rate of nitrogen fertilizer all decreased with the increase of nitrogen application rate The dry matter accumulation and nitrogen accumulation of 432 kg / hm2 and 540 kg / hm2 at high maturity were high, but the yield was low due to the large amount of nitrogen residing in the stem and sheath. The content of total nitrogen in all layers of soil decreased with the increase of depth. With the increase of nitrogen application, the content of total nitrogen in all layers increased from 0 to 60 cm, while the change trend of layers from 60 cm to 100 cm was not obvious. The soil nitrogen accumulation and infiltration were higher (more than 324 kg / hm2), and the content of total nitrogen in soil layers increased, which could easily lead to extravagant absorption of nitrogen fertilizer and nitrogen pollution.