施氮量对垄作小麦氮肥利用率和土壤硝态氮含量的影响

摘要

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氯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 kghm-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.%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.