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.