A Study On N Loss Characteristic And Interception Control Measures Under Different Slope Land Use Patterns In Red Soil Area

Slope cultivated land of red soil in China, riching in water and heat resources and great biological production potential, is one of the major land resources in Middle-Lower Yangtze region, and one of the highest population density and the most frequent human activities region. However, due to the lack of reasonable utilization for a long time, many problems, such as degradation of the natural vegetation, the serious water and soil erosion and the serious destruction of the soil ecosystem appeared in frequent.While the agricultural nonpoint pollution due to the loss of nitrogen in Slope cultivated land has become the current focus, so the study on the loss characteristic and the interception control measures of nitrogen was important to water environmental protection and agriculture sustainable development.In this study, the different fertilization and erosion control measures were used to research the N loss and runoff characteristic in different slope land utilization, the influence of different slope land use patterns on water environment were assessed.At the same time the control measures of nutrient loss on slope land were put forward.The results were as follows:(1)Paulownia forest fertilization had less effect on groundwater, the content of nitrogen of annual runoff was 70.0～451.3 g·hm-2, while the loss of sediment was 70.0～451.3 g·hm-2.The main form of the lost nitrogen in paulownia forest was dissolved nitrogen.Forest fertilization increased the concentration of DN, yet has little effect on the concentration N in sediment.So undergrowth cover can effectively reduce the quantity of the runoff sediment and the lost N in slop land.During the rainfall, the concentration of TP and NH4+-N reached the peak in about 20 minutes, and then decreased gradually, stabilized after 60-80 minutes.The NO3--N concentration in runoff reached the first peak in about 10 minutes, then rapidly decreased and reached a low point in 20 minutes, then gradually increased, reached the second peak in 60 minutes, then decreased gradually.(2)The quantity of lost nitrogen during the period of corn growth was reduced owing to decreased nitrogen fertilization, compared with the conventional fertilization, it reduced by 12.54-28.68%.But decreased nitrogen fertilization can not lessen the concentration of N in surface runoff.The N fertilizer fluctuating within 20% of the conventional can not impact maize production very significantly.However, when fertilizer reduced to 30%, the yield of maize reduced.To some extent, the reduction of fertilizer can not only improve the N, P fertilizer efficiency and utilization, but also lower the loss of N, P and reduce agricultural nonpoint pollution.(3)The surface runoff and sediment loss was effectively reduced by eco-blocking technology.Compared with CK, it can reduce the runoff by 5.7%-17.1% and the sediment loss 40.1%-45.6%. The removal rate of TN in surface runoff reached 26.5%-44.9%, so the effect of interception technology was very significant.This technology can not only increase corn production (compared with CK, corn production increased by 4%-8.1%) but also improved the NP fertilizer efficiency and utilization.(4)Compared slope farmland with the forest slope, the conclusion that the sediment loss of slope farmland was more than the forest slope.That is to say the sediment loss of slope farmland was 2.9 times as large as the forest slope in 2009, while the 2010s was 1.6 times.