Assessment of soil erosion and nutrient loss characteristics using fallout 137Cs on the Loess Plateau

The Grain for Green Project is one of the important projects implemented by the Chinese government to control soil erosion on the Loess Plateau, and its successful implementation has brought remarkable ecological benefits to relevant regions in China. The land use change is the most intuitive representation. Meanwhile, the soil erosion and soil nutrient distribution has also been influenced to produce significant changes. In this research, the characteristics of soil erosion and nutrient loss characteristics of soils from different land utilization types including apple, shrub, forest, grass and gully land, and their relationship were quantitative evaluated with ¹³⁷Cs tracer technique in a typical watershed, which is located in Yan'an city of northern Shaanxi province in China. Results showed that soil erosion was observed in the all-land use types but shrub land, however, the degree of soil erosion was slight (the maximum value of soil erosion rate for 151.27 t/km²•a). The soil erosion of forest was significant differences with apple, shrub and gully but not with grassland. As will as there were significant differences in among shrub, apple orchard and gully. The soil nutrient loss, soil nutrient status and soil erosion degree showed a very similar pattern of spatial variation, with the difference that the correlation coefficients were different. In addition, there was highly significantly positive correlation between three indicators. However, Soil total nitrogen, total phosphorus, organic matter, N/P and C/P significantly affected the total nitrogen loss, total phosphorus loss and organic matter loss, but C/N ratio and nutrient loss were not significant. Soil nutrient loss in small watershed was more closely related to the soil carbon and nitrogen and soil erosion. The basic contents of different nutrients affected their nutrients loss laws, by and large, soil erosion affected soil nutrient loss and results in differences in nutrient distribution in the small watershed.