施氮量对垄作小麦氮肥利用率和土壤硝态氮含量的影响

以平作为对照，研究了垄作种植方式下施氮量对冬小麦氮肥吸收利用、0~100 cm土层土壤硝态氮含量以及产量的影响。在一定范围内增加施氮量，小麦的氮肥利用率降低，土壤氮的贡献率降低，小麦植株内的氮素积累量增加，收获指数提高，产量增加。低氮(0~66 kg hm^-2)条件下，小麦生育期间土壤硝态氮淋洗损失的可能小，小麦收获后0~100 cm土体内不会累积大量硝态氮。施氮量在165~264 kg hm^-2时，60~100 cm土体内土壤硝态氮含量增加，出现硝态氮下移趋势。种植方式影响小麦的氮肥利用效率，垄作种植小麦氮肥利用率和产量均高于平作小麦。垄作种植麦田60~80 cm土体内土壤硝态氮含量相对较高，而平作种植麦田80~100 cm土层硝态氮含量相对较高。种植方式对氮肥利用率的影响大于施氮量的影响, 但施氮量对氮素收获指数、籽粒产量以及经济系数的影响大于种植方式的影响。本试验条件下，2种种植方式在施氮量为纯氮165 kg hm^-2时可以获得较高的氮肥利用率和氮素收获指数，平作小麦氮肥利用率为35.75%~36.41%，而垄作小麦为45.32%~47.25%; 但2种种植方式的小麦都是施氮量为纯氮264 kg hm^-2时获得最高产量, 平作和垄作小麦的最高产量分别达8 078.31 kg hm^-2和
8 212.27 kg hm^-2。

Effect of Nitrogen Application Level on Nitrogen Use Efficiency in Wheat and Soil Nitrate-N Content under Bed Planting Condition

The variation of nitrate-N content in soil was investigated in winter wheat under bed planting,and the N use efficiency and yield were compared between cultivation patterns of bed planting and flat planting.The amount of N accumulation in wheat plant,N harvest index,and grain yield of wheat were increased with the increase of N application rate,but the N use efficiency and the soil N contribution tended to decrease.At low N application rate(0-66 kg ha-1),the possibility of nitrate-N leaching was declined with no massive accumulation at 0-100 cm soil layer.At high N application rate(165-264 kg ha-1),the content of nitrate-N in 60-100 cm soil layer increased and began to move down in the soil.Cultivation patterns had an effect on N use efficiency,which of bed planting showed higher N use efficiency and wheat yield than flat planting.In flat planting pattern,nitrate-N was mostly accumulated in soil of 60-80 cm depth,which was shallower than that in flat planting(80-100 cm).Cultivation patterns had larger effect on N use efficiency than N application rate;whereas,N application had larger effect on N harvest index,grain yield,and harvest index than cultivation patterns.Under the experimental condition,high N use efficiency and N harvest index were observed in N application treatment of 165 kg ha-1,and the N use efficiency of wheat was significantly higher in bed planting(45.32-47.25%) than in flat planting(35.75-36.41%).The highest grain yields were 8 078.31 kg ha-1 in flat planting and 8 212.27 kg ha-1 in bed planting,which were both obtained in N application treatment of 264 kg ha-1.