N-15 isotope tracing of nitrogen runoff loss on red soil sloping uplands under simulated rainfall conditions

摘要

Stable isotope N-15 tracer technique was used in combination with artificial rainfall simulation to study the influence of interflow and surface-flow on nitrogen (N) migration loss of soil-plant systems on typical red soil sloping uplands. This study also investigated the utilization efficiency of fertilizer N during different peanut plant growth stages. The results indicated that soil N loss was predominantly via interflow and erosive sediment. Fertilizer N loss during the initial growth stage was mainly through surface runoff, while that occurred as interflow increased from less than 5% to around 16% during the middle and late growth stages. The loss of fertilizer N through surface runoff, erosive sediment and interflow accounted for over 18% of the total N application. The utilization rate of fertilizer N by peanut plants was around 45% through its life cycle, and that 70% of N absorbed by this plant derived from the soil. This highlighted the importance of adopting effective methods to reduce nutrient loss through interflow and surface-flow, the need to increase the utilization rate of fertilizers, and the importance to maintain soil fertility at a relatively high level.