氮肥运筹对夏玉米氮素利用及土壤无机氮时空变异的影响

Effects of Nitrogen Fertilization on Nitrogen Utilization and Spatial-temporal Distributions of Soil Inorganic Nitrogen in Summer Maize

研究不同施氮量及基肥追肥比例对土壤无机氮时空分布及玉米氮肥利用效率的影响。结果表明,不同施氮量和基追比显著影响土壤剖面硝态氮含量。各施氮处理不同生育期0～60 cm土层硝态氮含量均显著高于不施氮肥处理,且随施氮量的增加土壤中硝态氮含量增加。夏玉米生长季土壤铵态氮含量较低,且时空变化不明显。玉米氮素农学效率(NAE)、氮素利用效率(NUE)随施氮量的增加显著降低;氮素表观回收率(NRE)有相同的变化趋势,但差异不显著;氮素收获指数(NHI)随施氮量的增加显著增大。相同施氮水平下,"50%基肥+50%大喇叭口肥基追比"的NAE、NUE、NHI和玉米产量显著高于其他处理。因此,在玉米生产中应避免播种时一次性大量施用氮肥,增加后期施氮比例可显著提高氮肥利用效率和玉米产量。

The effects of the different nitrogen rate and proportions application of nitrogen fertilizer at sowing and later growth stage on soil spatial-temporal distributions of soil inorganic nitrogen, N use efficiency were studied. The results indicated that soil nitrate in the soil profile was significantly affected by different nitrogen fertilizer application amounts and rations of base N to dress N fertilizer. For all N treatments, soil nitrate levels at 0-60 cm depths in dif-ferent growth stages of maize were significantly higher than that of without N fertilizer treatment, and increased with the increase in the amount of nitrogen applied. Soil ammonium nitrogen content was low in the summer corn growing season, and there was not significantly changed in the spatial-temporal distributions. N agronomic efficiency （NAE） and N use efficiency（NUE） significantly decreased with increase in applying N fertilizer rate, but nitrogen apparent re-covery（NRE） was not significantly, and an opposite tendency of nitrogen harvest index（NHI） was showing. Under the same amounts of total applying N fertilizer, NAE, NUE, NHIN and maize yields with fertilization application method of 50%of base N＋50%of dress N fertilizer had higher values than that of other treatments. So, a disposable large num-ber of applications of nitrogen fertilizer at sowing should be avoided, on the contrary, the increase in the proportion of late N application can significantly improve nitrogen use efficiency and yields of maize.