Reduction In Nitrogen And Phosphorus By Experimental Riparian Vegetation Buffer Zone Bulided In Beixi Of Jiulong River

Extensive use of nitrogen and phosphorus fertilizer increases the crop yields, but also causes serious agricultural nonpoint source pollution. Riparian vegetation buffers as ecological engineering measures have significant effects in controlling agricultural non-point pollution. Rainfall runoff observation combined with field simulating runoff experiments were carried on to study the reduction effects of runoff volume, nitrogen and phosphorus pollutants in vegetation buffer zones of different width combination Pennisetum and different shrub species and herb combination.In this study, the reduction of nitrogen and phosphorus in rainfall runoff the Beixi of Jiulongjiang river experimental riparian buffer zones in July to September 2015 were oberserved, and field simulation tests were runned to reveal the effects of different widths and different vegetation buffer zone on the situation of nitrogen and phosphorus reduction. The results showed that, ?1? Buffer zones reduced nitrogen better than phosphorus; The difference of reduction effects on surface runoff and subsurface flow were not significant; In two different concentrations of simulation experiments, the reduction rate was higher in high concentration experiments than in low concentration experiments. ?2? The optimum width combinations of Pennisetum and weeds in natural rainfall runoff for reducting NO3--N, NH4+-N, TN, PO43--P and TP were Pe₂₀, W₂₀, W15+Pe5, W10+Pe10 and W10+Pe10, and the average reduction rates were 80.2%,41.3%,65.2%, 66.8%and 62.6% respectively; The optimum width combinations of Pennisetum and weeds for high-concentration simulaiton experiments for reducting NO3--N, NH4+-N, TN, PO43--P and TP were Pe2o, W15+Pes, W15+Pe5, W10+Pe10 and W10+Pe10, and the average reduction rates were 14.4 %,97.1%,95.5%,96.1% and 95.9% respectively; The optimum width combinations of Pennisetum and weeds for low-concentration simulation experiments for reducting NO3--N, NH4+-N, TN, PO43--P and TP were W₂₀, W10+Pe10, W₂₀, W15+Pe5 and W15+Pe5, the average reduction rates were 12.0%,81.6%,58.6%,93.3% and 92.9% respectively. For redcting runoff volume, nitrogen and phosphorus grosses, the optimum width combination of Pennisetum and weeds was W10+Pe10, the average reduction rate were 96.93%,99.15% and 99.90% respectively. ?3? From the results of combinations of different vegetation species buffer zones, for NO3--N, TN, PO43--P and TP reduction effects, the optimum vegetation sepecies combinations in natural rainfall runoff were Pe₂₀, W₂₀, W₂₀ and W₂₀, and the different combinations of vegetation buffer zones showed no significant difference to reduce NH4+-N. In high-concentration experiment, the best combination for different forms of nitrogen reduction of buffer zone was the Pe₂₀ and the best combination for different forms of phosphorus reduction of buffer zone was the W₂₀.In low-concentration experiment, the best combination of different forms of nitrogen reduction of buffer zone was the W₂₀ and the best combination of different forms of phosphorus reduction of buffer zone was the Pe₂₀. For redcting runoff water volune, the best combination was W10+Pe10, the average reduction rate was 94.38%. Different combinations of vegetation species buffer zones of nitrogen and phosphorus grosses reduction showed no significant difference. ?4? According to the reduction effects of nitrogen and phosphorus concentration and total amount for natural rainfall and runoff simulation field experiment, the proposed riparian buffer zone would be W10+Pe10; considering landscape demands and reduction effects, the proposed riparian buffer zone would be L10+Pe10.We conclude that the riparian vegetation buffer zone is very effective in reducing runoff volume, nitrogen, and phosphorus concentrations and grosses in controling agricultural non-point source pollutions, and has important scientific and practical significance for solutions of eutrophication pollutions. Moreover, the results provide theoretical basis for the application and popularization of riparian vegetation buffer zone technology in our country. and Riparian vegetation buffer zone can improve the surface water quality, and is conductive to ensure the safety of drinking water in the Beixi of Jiulong River basin.