冀北高原草甸栗钙土春小麦中化肥氮去向的研究

在冀北高原张北县的草甸栗钙土上，采用＾１５Ｎ质量平衡法和微气象学技术，对春小麦中氮肥的去向，以及氨挥发进行了田间原位观测。试验中的氮肥用量为Ｎ４．８３ｋｇ／亩，１／３作基肥、２／３作追肥。基肥随播种施入，追肥于拔节期撤施，随即灌水。结果表明，小麦回收、土壤残留和损失的肥料氮各占施入氮量的３７．８％－４８．３％、３３．８％－４０．４％和１４．３％－２５．４％。其中，尿素作基肥与作追肥的处理之间，其氮

FATE OF FERTILIZER NITROGEN APPLIED TO SPRING WHEAT GROWING ON A MEADOW CHESTNUT SOIL IN PLATEAU OF NORTH HEBEI PROVINCE

Fate of fertilizer N was investigated by the ¹⁵N mass balance method, and ammonia volatilization was measured by the micrometeorological technique after urea or ammonium bicarbonate was applied to spring wheat growing on a meadow chestnut soil at Zhangbei County, Hebei Province. The application rate of N fertilizer was totally 72.SkgN/ha, of which 1/3 was applied as basal dressing with seeding, and the rest 2/3 was applied as top dressing imn>adiately followed by irrigation.Results showed that plant recoveries, N remaining in 0-0.8m soil and total N losses of the applied N were 37.8%-48.3%, 33.8%-40.4% and 14.3%-25.4%, respectively. There was no apparent difference between the fates of urea N applied as basal dressing and top dressing. However, while N fertiliser was applied as top dressing, plant recovery was 10% higher from urea than from ammonium bicarbonate, and in contrast, N loss was 7.5% lower from the former than from the latter.volatilization was as low as 1% and 5% of the applied N when urea and ammonium bicarbonate were applied as top dressing, respectively. Results also showed that less than 1/3 of the N taken up by wheat was derived from the applied N fertilisers, and thus the rest was derived from the soil.