用15N肥料标记法研究潮土中玉米氮肥的利用率与去向

【目的】特定作物体系中氮肥的去向很难做到定量化。本文以玉米为供试作物,解析潮土上玉米作物氮素肥料利用、 转移规律,探讨肥料氮、 土壤氮与作物氮之间的关系。【方法】采用15N标记和盆栽培养技术,在北京市农林科学院人工控温温室条件下进行模拟研究,设置10个施氮水平(0、 22、 44、 66、 88、 111、 133、 177、 222、 266 mg/kg N),分析植株氮素利用和土壤氮素供应特征,研究潮土种植夏玉米条件下氮素肥料的运移规律及不同氮肥剂量对夏玉米的作用效应。【结果】所有施氮处理均显著提高了玉米生物量和植株吸氮量。氮肥利用效率虽然随施氮量增加有升有降,但处理间差异不显著。夏玉米对15N标记氮肥的回收率为9.01%~67.57%,土体中15N残留率和损失率分别为21.40%~40.54%和11.04%~50.45%,均随施氮量的增加而显著增加。与N1~N3(22、 44、 66 mg/kg)施肥水平处理相比,N4(88 mg/kg)处理条件下15N肥料在土壤中残留率分别减少19.14、 12.38、 13.13个百分点;15N肥料的损失率分别降低39.41、 7.88、 13.88个百分点。氮肥施用量超过88 mg/kg时,各个处理条件下玉米植株生物量和氮肥回收率出现降低趋势,分别降低5.88%~8.0%和9.06%~27.81%;15N肥料在土壤中的残留率和损失率分别减少3.36%~17.30%和1.65%~13.57%。【结论】该试验条件下,玉米的合理施氮量为88 mg/kg时,氮素的利用率最高为67.57%,残留率和损失率最低,分别为21.40%和11.04%,对生态环境的压力较小。

Nitrogen use efficiency and behavior studied with 15N labeled fertilizer in maize in fluvo-aquic soils

【Objectives】 In this study, an experiment was conducted for quantitative characteristics of nitrogen (N) fertilizer utilization and the fate of fertilizer N on “N uptake-soil residues-loss” in summer maize in Beijing Academy of Agriculture and Forestry in 2013. 【Methods】 A pot experiment was carried out using 15N-label method inside an artificial weather shed. Ten N fertilizer application rates were designed with three replicates: 0, 22, 44, 66, 88, 111, 133, 177, 222 and 266 mg/kg. The characteristics and nitrogen utilization of soil and maize plant were measured.【Results】 With the increase of N fertilizer applied, there was no significant difference in N fertilizer use efficiency, but showed a tendency of rising firstly and then falling. Agronomic efficiency of applied N-fertilizer and apparent N fertilizer recovery efficiency decreased significantly. The recovery ratio of 15N was 9.01%-67.57% in maize season and the percentage of residual 15N in soil was 21.40%-40.54%. Residual 15N rates of different soil layers increased significantly with the increase of N fertilizer applied and decreased notably. Loss rates of 15N increased significantly with the increase of N fertilizer applied and total 15N loss ratio was 11.04%-50.45%. Compared with N 22, 44 and 66 mg/kg treatments, the soil N accumulation was reduced by 19.14%, 12.38% and 13.13% in N 88 mg/kg treatment, respectively. Moreover, the N loss rate was reduced by 39.41%, 7.88% and 13.88%, respectively. Compared with N 111, 133, 177, 222 and 266 mg/kg treatments, the plant N accumulation was increased by 5.88%-8.00% and the N recovery rate was increased by 9.06%-27.81% in N 88 mg/kg treatment. In the other hand, the soil N accumulation was reduced by 3.36%-17.30%, and the N loss rate during the maize growing period was reduced by 1.65%-13.57%.【Conclusions】 Under the condition of this experiment, proper rate of N applied in maize was recommended at 88 mg/kg, and N use efficiency was the highest with 67.57%, and the percentage of residual N and loss rate of N were the least with 21.40% and 11.04%, presenting less pressure to the environment.