Characteristics And Countermeasures Of Nitrogen Loss From Slop Farmland In Suopo Watershed

Fenhe Reservoir is the largest drinking water sources in Shanxi Province. For a long time, slope farmland cultivation has been widespread in the upper reaches of the reservoir. With addition of serious soil erosion, soil nutrient flows into the Fen River with runoff sediment and thus results in increasingly prominent problems in reservoir eutrophication. A study on soil erosion of slope farmland, nutrient loss and prevention in Fenhe Reservoir upstream is of great significance for maintaining the function of soil and water resources in water sources and improving the ecological environment.Based on the investigation and evaluation of physical and chemical properties, land use structure, the main pollutant load of small watershed soil resources, through soil erosion dynamic monitoring, indoor simulation test, and other means, this study carried on qualitative and quantitative analysis on the mechanism of runoff and sediment yield in slope farming, surface source pollution formation process and nitrogen loss characteristics on different crop conditions, and further clarify the effects of different crops on slope land runoff, sediment formation and nitrogen loss. On the basis of this, the amount of nitrogen loss in the larger area of sloping farmland was estimated.this study first put forward the measures of the buffer zone of the slope farmland crops, and conducted research and analysis on the crop buffer zone in the field of prevention and control of of nitrogen loss.Besides, this study preliminary proposed thoughts and countermeasures on prevention and control of non-point source pollution on Sloping Farmland. Main conclusions are:?1? Soil loss amount from five slop farmland uxse patterns under six effective rainfall have great differences. The order of accumulated soil loss amount was:bare land> potato land> naked oats> no-planted land> corn. Ground vegetation types have significant effects on soil loss, it is one of the factors that influence the amount of soil loss. Soil loss amount increased with the runoff, and existed effective difference between different vegetation conditions. The part of sediment in runoff have great difference between different vegetation condition, and the proportion decreased with the time extending for naked oats land, potato land and bare land, while increased for corn land and abandoned land.The ratio of sediment was:naked oats> potato land> bare land> no-planted land> corn land. Vegetation coverage did not significantly effect on the amount of soil loss, and not show a constant trend.?2? Monitoring time, land use pattern have significant effect on NO₃^--N, TN, NO₂^--N and NH4+-N concentration respectively. Exception the bare land, NO₃^--N concentration showed a gradual decline. NO₃^--N concentrations were:bare land> corn land> naked oats> potato land> no-planted land; TN concentration firstly increased, then decreased. The order was bare land> potato land> no-planted land> corn land> naked oats; NO₂^--N concentration was increased and then decreased. The order was bare land > potato land> naked oats> corn> no-planted land. NH4+-N concentration firstly increase, then decrease, and finally increase again. The order was naked oats> no-planted land> corn land> potato land> bare land. NO₃^--N and TN concentrations have significant difference, but NO₂^--N and NH4+-N concentration no significant difference.?3? Inorganic nitrogen loss from 10m² experimental plot with runoff from a few grams to tens grams, and order was bare land> potato land> no-planted land> naked oats> corn land. NO₃^--N and NO₂^--NN loss have significant difference, and NH4+-N no difference under different vegetation condition.?4? Organic nitrogen loss was increased, and have significant difference. The loss order was:bare land> potato land> no-planted land> naked oats> corn land. TN loss order was:bare land> potato land> no-planted land> naked oats> corn land.?5? The ratio of loss NO₃^--N and loss TN showed a gradual downward trend, and the order was:corn land> bare land> naked oats> no-planted land> potato land.The ratio of loss NO₂^--N and loss TN firstly increasing then decreasing, and the order was:bare land> potato land> no-planted land> naked oats> corn land. The ratio of loss NH4+-N and loss TN showed a gradually downward trend, and the order was:naked oats> corn land> no-planted land> potato land> bare land. The order of ration of loss organic N land loss TN was:potato land> no-planted land> bare land> naked oats> corn land.?6?During July 9-9 September, the order of soil loss from slop farmland was:bare land> potato land > naked oats> no-planted land> corn land. Hundred to over one thousand tons of soil loss from slop farmland one year in Suopo watershed have significant influence on land productivity and sustainable development. Great loss soil will caused enormous damage to downstream channel, and threat to safe and effective of rivers, lakes and reservoirs.?7? During July 9-9 September, the order of TN loss from slop farmland was:bare land> potato land > no-planted land> naked oats> corn land. Tens to one hundred ton of TN loss from slop farmland one year in Suopo watershed have enormous damage to land productivity and sustainable development.?8? Focus on the characteristics of land structure, and the weak of traditional agricultural, propose the main idea of land rearrangement in Suopo watershed. The main idea was transformation slop farmland by the engineer measures. From these measure to reduce the area of slop farmland, and develop diversity agriculture cropping patterns. From these measures will achieve the role of reduced the soil and nutrient loss, finally aimed to achieve sustainable development of ecological and agriculture.