Soil Redistribution investigations by combined use of soil 137Cs and selected chemical properties

Abstract

The 137Cs spatial redistribution data have been widely used to estimate soil redistribution rates over the past 45 years approximately. However, the frequent changes in land use in China have limited the general application of the 137Cs tracer technique to soil erosion or deposition budget on the mid- / long-term. In this paper, soil 137Cs measurements and some chemical properties, such as the soil organic carbon and available phosphorus contents, were simultaneously used to identify sediment sources and to reveal the spatial characteristics of soil redistribution. The deposition rates after and before the changes in local land use could be estimated using the approach proposed in this study. The reclamation of formerly uncultivated slopes was found to lead not only to striking accelerated soil erosion but also to considerable changes in the slope form. A typical footslope site on 5-year-old reclaimed sloping land which appeared to have experienced net erosion before 1997, has become a site with deposition reaching a rate of 3.0 cm year−1 since 1997. Besides the soil 137Cs activity, the soil organic carbon content was found to be a very meaningful indicator of the extent of soil erosion or deposition, and the significant difference in the soil available phosphorus content between uncultivated and cultivated land could become a very sensitive and suitable criterion for identifying sediment sources under different land uses.