通过田间试验,研究不同氮素水平(0、150、200、250、300、400 kg/hm²)对春玉米植株地上部分吸氮量、农田矿质氮平衡和玉米产量的影响。结果表明,土壤中矿质氮随土层深度的增加逐渐降低,硝态氮在20～40 cm和100～120 cm各有1个积累峰值。在0～40 cm土层深度内,N0和N150处理铵态氮含量低于其他处理。当施氮量<264.16 kg/hm²时,玉米植株吸氮量与施氮量呈正相关;当施氮量≥264.16 kg/hm²时,施氮量对玉米植株吸氮量增加不显著(p<0.01)。0～120 cm土壤氮素表观损失量和施氮量呈正相关,当施氮量< 221.36 kg/hm²时,氮肥供应不足。本试验条件下,化学氮肥施用阈值为221.36～264.16 kg/hm²,最高产量施氮量为252.93 kg/hm²。

The field experiment was conducted to investigate effects of nitrogen application on spring maize in yield, crop nitrogen uptake and mineral nitrogen(N min) balance, that designed to 6 levels of nitrogen application rates(0, 150, 200, 250, 300 and 400 kg/ha). The results showed that, N min content with increasing soil depth was gradually reduced, which ammonium nitrogen(NH₄⁺-N) and nitrate nitrogen(NO₃^--N) had two peaks in the soil depth of 20-40 cm and 100-120 cm, respectively. N0 and N150 treatment NH₄⁺-N content was lower than the others on the soil depth of 0-40 cm. There was positive correlation between the crop nitrogen uptake and nitrogen fertilizer ap-plication < 264.16 kg/ha(p<0.01), there was not significant while N application ≥ 264.16 kg/ha. There was positive correlation between the apparent nitrogen loss and N application in the soil depth of 0 -120 cm, namely, nitrogen fertilizer was short supply in field when N application < 221.36 kg/ha. In conclusion, a reasonable nitrogen applica-tion rate should be about 221.36-264.16 kg/ha, nitrogen application rate of the highest yield was 252.93 kg/ha.

农业部行业专项经费项目“主要农区农业面源污染监测预警与氮磷投入阈值研究”(201003014-4)、科技部科技支撑计划“ 环渤海辽宁增粮技术集成与示范”(2013BAD05B07-02)