摘要
Vegetable runoff nitrogen(N)loss is a serious environmental issue.However,whether the volume or N content of runoff determines the final N losses has not been clarified,which limited the optimal N managements in vegetable production.Here,we conducted a simulated rainfall experiment to study the runoff N loss flux pattern and the accumulation rate as well as the main influencing factors.The results showed that at 20 to 30 min,the volume of runoff water with a high N content reaches a critical inflection point of increase.Under 55 mm/h rainfall intensity,the N concentration decreased continuously.Under 75 mm/h,the soluble N concentration decreased during the first 25 min;thereafter,it stabilized.However,the total and particulate N decreased significantly after 30 min.Nitrogen losses via runoff from vegetable fields were from 18.5 to 26.0 kg/ha under two rainfall intensities.Runoff soluble N losses were mainly attributed to applied fertilizers(79.7%-95.5%),while particulate N losses were primarily originated from soil-retained N.Our data indicates that there was a significant difference in N losses pattern and influencing factors under varied fertilizer N inputs and rainfall intensities,which can help to optimize water and N fertilizer managements to mitigate non-point source N pollutants.In the future,long-term multi-site and-crop studies should be conducted to comprehensively clarify the N runoff losses in vegetable soils.
基金
supported by the National Key Research and Development Program of China(No.2021YFD1700801).
