Study Based On ¹³⁷Cs Technique Of Soil Erosion Of Farming-pastoral Transitional Zone In North China

Soil erosion caused soil degradation, water pollution and a series of eco-environmental problems, which are not only the world's attention, but also agriculture and eco-environmental sustainable development important problems. Farming-pastoral Transitional zone in north China, as our county returning farmland to forest and returning cropping land to grassland are the focus areas, natural environment and socio-economic conditions shown a clear transition characterized by the transition zone of the interpenetration and staggered distribution of agriculture and animal husbandry, which is curbing desertification important ecological barrier, but also ecologically fragile belts.In this study, two study areas Lanzhou and Datong are selected in the farming-pastoral Transitional zone of north China, and collected the background samples and the entire sample a total of 64 samples, with the United States produced by ORTEC model GMX50P4N-type coaxial high purity germaniumγdetector under different land use patterns of the ¹³⁷Cs content in soil samples, and learned that in Lanzhou ¹³⁷Cs content of the land-use types in descending order was as follows: flat grassland, flat farmland, slope shrub, slope farmland, the fruit between farming, slope woodland, slope farmland, and slope grassland, and in Datong the ¹³⁷Cs content of various land use types in descending order was as follows: flat grassland, slope grassland, flat woodland, slope farmland, flat abandoned lands, and slope scrub.In the study area, According to Background value principle respectively determined the background value of ¹³⁷Cs. the background value of the study area were as follows: Lanzhou(1707.4Bq/m²), Datong(1836.3Bq/m²). Then according to the study area identified by the background value of ¹³⁷Cs and ¹³⁷Cs content of the sample measured, using mass balance model and the proliferation of ¹³⁷Cs depth distribution and migration of complex process physical model are made by walling, and He, and respectively calculated soil erosion rate of farmland and non-tillage farmland. In Lanzhou different land use types of soil erosion rate range of 1200- 76000t/km²Â·a, where slope farmland erosion rates of up to 76000 t/km²Â·a, slope grassland of 8300 t/km²Â·a, slope woodland for 7500 t/km²Â·a, fruit farming intercropping for 5200t/km²Â·a, slope abandoned lands for 4100 t/km²Â·a, flat farmland for the 2300 t/km²Â·a, slope shrub erosion rates for 1200 t/km²Â·a , flat grassland produced a certain amount of accumulation, accumulation rate of 2860 t/km²Â·a. In Datong soil erosion rate of different land use types range of 600-17500t/km²Â·a, of which the erosion rates of slope farmland and flat farmland of up to 17500 t/km²Â·a, the erosion rate of slope shrub 7700 t/km²Â·a, flat woodland erosion rate of 600 t/km²Â·a, where the slope grassland and flat grassland occurred in a certain degree of accumulation, which the accumulation rate of the grass slope 620 t/km²Â·a, and the accumulation rate of flat grassland 1760 t/km²Â·a.From the analysis of man-made cause soil erosion that Whether the surface shape is slope land or flat land, and regardless of farmland, woodland or scrub, because of the involvement of human activities, resulting migration of soil particle of varying degrees, the result is leading to these land-use types had different degrees of soil erosion. Basically no impact of human activities place on the grassland in a certain extent the chances of soil erosion is relatively small, the degree of weak, resulting in greater risk of soil accumulation.From the analysis of natural cause soil erosion, the study area's vegetation coverage, local rainfall, as well as strong wind days will be on the study area of soil erosion under different land use types have some impact.