Effects Of Controlling The Loss Of Nitrogen And Phosphorus On The Orchard With Different Measures

The study was carried out on the orchard of red soil slope land .By setting five different measures, which were strip covering, covering in the whole orchard, cleaning tillage, terrace I, terrace II , the effects of measures on controlling the soil erosion and nutrient losses were studied, and the relationship between nutrient losses and rainfall was anaylsed. The results showed that:Compared with cleaning tillage, the way of covering in the whole orchard is the most effective method to conserve water and soil. It reduces the runoff by 83 % and the amount of soil erosion almost 100% on average. Other treatments also result in some positive effects.The loss of nitrogen and phosphorus caused by cleaning tillage was most serious. During 2004-2006, The loss of N and P loadings were higher than 30 kg/hm~2 and 8 kg/hm~2 per year on average, and the top loading even reached 46 kg/hm~2 and 24kg/hm~2, respectively. Compared with cleaning tillage, the biological and engineering measures were more effective in decreasing the loss of nitrogen and phosphorus, and the loss was decreased by more than 90%.Runoff was the major way of the loss of N and P when the biological and engineering measurements were taken. Whereas, sediment losses was the predominant when cleaning tillage was taken. Nitrogen loss was mainly due to dissolved loss, accounting for more than 80% of the total losses. Particulate phosphorus was the major from of phosphorus loss, which accounted for more than 99% of the total losses.Rainfall is the main reason for nutrient loss. The relationships among rainfall, runoff amount and amount of nutrient losses were remarkable or even greatly remarkable. The analysis of the nutrient losses with the month indicated that the more rainfall in a month, the more nutrient losses. The influence of rainfall on sediment nutrient loss was different depending on vegetation cover degree of the surface. Among the five treatments, the rate of vegetable cover in the whole orchard and level bench terrace I reached 100%, and there was no certain relativity between rainfall and nutrient loss. The rainfall intensity had no distinct influence on the runoff nutrient losses. Also, the influence of rainfall intensity on sediment nutrient loss was different depending on vegetation covers of the surface. A certain relativity only exist in the treatments of cleaning tillage and level bench terrace II.