The Effect Of Engineering Technology On The Nitrogen And Phosphorus Losses In Runoff From Tea Fields Of Hilly Land

Tiaoxi watershed is one of the main production areas of tea in Zhejiang province. With the increasing of the market demands for tea, the tea fields increased fast in recent years. For quite a long time, the local farmers lack the consciousness of water and soil conservation and usually use the improper ways to manage the tea fields. Therefore, the utilization rate of fertilizers is lower. Moreover, because the tea fields in this area locate in hilly and sloping land, the water, soil and nutrition are easy to lose. In such a situation, the pollution loads of nitrogen and phosphorus from tea fields are higher. In order to reduce the loads of non-point nitrogen and phosphorus pollution and improve the water quality of Tiaoxi watershed, the control technique of nitrogen and phosphorus losses in surface runoff from hilly tea fields using the relevant engineering methods has greater realistic significance.In this study, technical engineering demonstration areas are established, the application effects of liquid eco-membrane protection technology, slow-release fertilizer technology and eco-pond-ditch technology on soil and water nutrition erosion were investigated. The results were listed below:(1) In natural rainfall condition, the tea field with eco-membrane mulching was compared with conventional till, the effects of eco-membrane mulching on nitrogen (N) and phosphorus (P) losses in surface runoff from tea fields are investigated. The results showed that, compared with conventional till, the concentration of TN, nitrate N, ammonia N, TP, total dissolved P and particulate P from eco-membrane mulching treatment reduced by21.30%,16.08%,25.01%,33.33%,17.51%and37.61%, respectively.(2) In order to investigated the control effects of slow-release fertilizer on N and P losses in surface runoff from tea fields, slow-release and conventional chemical fertilizers were applied to different tea fields at the same rates. The results showed that, compared with conventional fertilizer, the concentration of TN. nitrate N, ammonia N, TP, total dissolved P and particulate P from slow-release fertilizer treatment reduced by32.14%,29.45%,33.45%,26.67%,35.01%and22.02%, respectively.(3) Through the application of eco-pond technical engineering, the concentrations of N and P in the outflow of eco-pond were obviously reduced. Compared with mean concentration of N and P in runoff from tea fields, the concentrations of TN, nitrate N, ammonia N, TP, total dissolved P and particulate P in the outflow of eco-pond were reduced by32.61%,44.81%,25.87%,37.01%,26.12%and41.37%, respectively. Through the application of eco-pond technical engineering,the ecological cost of the tea fields will reduce264Yuan/y.