Primary Study On The Character Of Nitrogen, Phosphorus And Potassium Surface Runoff In Latosol Of Rubber Plantations

The latosol is a zonal soil in the tropical rain forest and monsoon forest areas in hainan province of China,with sufficient light and heat,the rainfall concentrated with obvious dry and seasons. The average annual rainfall1400-2700mm, rainy season accounted for more than80%of the annual precipitation, and short-term strong rainfall occurred frequently, surface soil erosion resulting in severe a loss of soil nutrients with surface runoff. This article through the no fertilization and fertilization treatments, using the large field catchment area field monitoring, systematic study of natural rainfall conditions, nitrogen, phosphorus and potassium loss with surface runoff of the latosol, trying to provide a scientific basis for the assessment of the impact of the rubber plantation woodland latosol rubber surface runoff and nutrient loss. Primary study result show that:1. The rainfall runoff of nitrogen loss characteristicsNitrogen loss in the rubber plantation latosol rainfall runoff, Loss of nitrogen different concentration in runoff throughout the rainy season, the rainy season comes in May (before3times) heavy rainfall caused nitrogen loss was significantly higher than the late, which ammonium nitrogen runoff loss of form; to prevent massive loss of rubber plantation soil nutrient nitrogen critical period of the previous heavy rainfall in the rainy season.Fertilization conditions, with the increase in fertilizer to N3level (225kg/hm2), the loss of total nitrogen, ammonium nitrogen concentration was significantly increased, the increase of which the total nitrogen concentration to reach a significant level. The highest loss of total nitrogen concentration of6.99mg/L, far exceeding the GB3838-2002"surface water environment quality standards'TN v class of agricultural water district standards limit2mg/L, and a lot of runoff water long-term direct access to nearby water bodies, may water ecological hazard.2. The rainfall runoff phosphorus loss characteristicsThe concentration of total phosphorus loss in the whole monitoring process is relatively stable, but several heavy rainfall (September13, October3) on soil erosion severe, resulting in sharp increase of the total phosphorus concentration in runoff. The first time after fertilization, fertilizer application rate increased to255kg/hm2, the level of total phosphorus loss was increased significantly.3. The rainfall runoff potassium loss characteristicsRainy season, the early loss of water-soluble potassium concentration is much higher than the late, after the first fertilizer, potash fertilizer application rate increased to94kg/hm2, the level of water-soluble potassium loss increased significantly, and two fertilization did not significantly increase the runoff loss of concentration.4. The rainfall runoff soil nutrient loss with sediment characteristicsEarly rainfall runoff (May8) loss of nutrient content in the sediment were significantly enriched, available P, K enrichment in the entire process of runoff and sediment loss is relatively large. Increase fertilization on the loss of sediment, total nitrogen, available phosphorus nutrient content of a significant increase in fertilization did not increase the organic matter, potassium nutrient loss. Therefore, the loss of rainfall runoff process, combined with the nutrient content of the state loss to the sediment is also considerable.