Assessment of management practices in a small agricultural watershed in Southeast China.

In this study, an event-based agricultural non-point source pollution model (AGNPS) was calibrated and validated in an agricultural watershed in Southeast China. The AGNPS predicted runoff, peak runoff rate, nitrogen and phosphorus well matched the observed value during calibration and validation. The validated model was then applied to simulate performance of the two existed management practices and three alternative scenarios using current management practices as background losses of non-point source (NPS) pollutants. Simulations showed that the existed management practices (contour cultivation and multi-pond system) were very effective in reduction of nutrient losses. Although alternative practices, such as improved nutrient management, conversions of current orchards to woods, and their combined practices, certainly reduced the NPS pollutants from the watershed, a detailed cost-benefit analysis is necessary to select practices that could be implemented for further reduction of agricultural NPS pollutants.