Abstract:Excessive nitrogen (N) fertilization input has resulted in fertilizer waste and soil quality degeneration, etc. Based on the last 3-year results of the effects of different N fertilizer management models on soil agronomy, fertilizer and environment efficiency, an optimum N fertilizer management model was selected. To indentify the model and investigate the fate and utilization of the chemical N fertilizer, a microplot experiment with 15N tracing technique was carried out in Shouguang, Shandong Province, which is the famous greenhouse vegetable production base in Northern China. The experiment included the conventional N fertilizer model (FP) and optimized N fertilizer model (OPT). The main findings are that the higher dry matter production and N content are obtained in the OPT model and only about 20% of N uptake of plants comes from chemical N fertilizer. Compared with the FP model, the agronomic efficiency and N recovery efficiency of chemical fertilizer N are significantly increased in the OPT model. NO-3-N is the main chemical N residue form, and the NO-3-N accumulation amounts in 0-100 cm soil layer of the two models are N 536.9 and 340.3 kg/ha respectively.NO-3-N is mainly accumulated in 0-40 cm soil layer, and NO-3-N accumulation amounts are decreased with the increase of soil depth. Compared with the FP model, soil NO-3-N accumulation amounts in each soil layer of the OPT model are significantly decreased. 32.4% and 8.2% of 15N loss are from the chemical N fertilizer, respectively in the FP and OPT models, and the N loss rate of the OPT model is 24.2% lower than that of the FP model. The present study shows that the OPT model can improve chemical N fertilizer uptake and utilization, reduce chemical N fertilizer loss and maintain the sustainability of greenhousebased intensive vegetable systems.