施氮与灌水对夏玉米土壤硝态氮积累、氮素平衡及其利用率的影响

通过田间裂区试验研究了不同施氮量(N 0、150、210和270 kg/hm2)和灌水量(900、1200、和1500 m3/hm2)对夏玉米土壤硝态氮分布累积、氮素平衡以及氮肥利用率的影响。结果表明,夏玉米收获期各处理土壤硝态氮在表层(0—20 cm)含量最高,在0—200 cm剖面均呈现先减少后增加再减少的变化趋势;土壤剖面NO3--N累积量随施氮量的增加而增加,且施氮处理硝态氮积累量显著高于不施氮处理。作物吸氮量、氮素表观损失量均与施氮量和总氮输入量呈显著相关,氮素输入量每增加1 kg,作物吸氮量仅增加0.301 kg,而表观损失量增加0.546 kg,是作物吸氮量的1.8倍左右。随施氮量的增加土壤剖面中NO3--N的损失量逐渐减少。夏玉米子粒吸氮量和收获指数随施氮量的增加有增加的趋势;氮肥回收效率和氮肥农学效率均以处理W1500N150最高,分别为46.15%和12.98kg/kg;氮肥生理效率以处理W1200N150最大,为34.49 kg/kg。本试验条件下,以水氮处理W1500N150的土壤硝态氮残留量、表观损失量较低,夏玉米氮肥回收效率和农学效率较高。

Effects of nitrogen application and irrigation on soil nitrate accumulation, nitrogen balance and use efficiency in summer maize

The field experiment was carried out to investigate the effects of different nitrogen and irrigation levels on soil nitrate accumulation, nitrogen balance and use efficiency in summer maize using the split-plot design. There were three irrigation levels, 900 (W₉₀₀), 1200 (W₁₂₀₀), and 1500 m³/ha (W₁₅₀₀) in main plots and four nitrogen levels, 0 (N₀), 150 (N₁₅₀), 210 (N₂₁₀), and 270 kg/ha (N₂₇₀) in sub-plots. The results show that, the highest soil NO^-₃-N content is observed at 0-20 cm soil layers at the harvest stage of summer maize. Soil NO^-₃-N contents fluctuate with the increase of depth in 0-200 cm soil profiles. There is significant correlation between NO^-₃-N accumulation amounts in the soil profile and the nitrogen application amounts, the NO^-₃-N accumulations of the nitrogen treatments are significantly (P＜0.05) higher than those of the non-nitrogen treatments. The crop nitrogen uptakes and nitrogen apparent losses are positively correlated with the nitrogen application rates. As the total nitrogen input increased by 1 kg, the crop nitrogen uptake and nitrogen apparent losses are increased by 0.301 and 0.546 kg, respectively. The nitrogen apparent losses in the soil profile are decreased with the increase of the nitrogen application. The nitrogen harvest index and grain N absorption of summer maize are increased with the increase of the nitrogen application. The highest nitrogen recovery efficiency and agronomic use efficiency are obtained in the treatment of W₁₅₀₀N₁₅₀, about 46.15% and 12.98 kg/kg, respectively, and the highest physiological use efficiency is observed in the treatment of W₁₂₀₀N₁₅₀, about 34.49 kg/kg. In our experiment, the optimal combination of nitrogen and irrigation isW₁₅₀₀N₁₅₀ for the lower amount of soil NO^-₃-N residual and nitrogen apparent losses, and the highest nitrogen recovery efficiency and agronomic use efficiency.