Characterizing soil losses in China using data of 137Cs inventories and erosion plots

Abstract

A large area of lands are subject to soil erosion, which affects the soil ecosystem service by causing soil degradation and soil organic carbon (SOC) changes. Robust estimations of soil loss rates are of key importance to understand relevant controlling factors as well as reducing soil losses. This study utilized complied data derived from 137Cs inventories and erosion plots to quantify soil loss rates in China as well as investigating controlling factors of soil loss rates. Comparison between results from different methods was also conducted to understand the advantages of each method. Our results showed that soil loss rates of cultivated soils derived from both methods were significantly higher than those of uncultivated soils, and soil loss rates were generally positively correlated with the slope gradient and the slope length. There were discrepancies between soil loss rates derived from 137Cs inventories and those from erosion plots due to the different erosion processes and spatio-temporal scales that these two methods focused on. The 137Cs loss ratio was identified as the largest source of variations in the estimated soil loss rates by conversion models. Existing studies have failed to collect enough soil samples to correctly estimate the reference 137Cs inventory, and considerably overestimated the soil loss rates by assuming a default value of unit for the particle size correction factor.