Quantitative determination of red-soil erosion by an Eu tracer method

Soil erosion is a serious problem and it is affected by land use and tillage (positive or negative). Even though there are a lot of studies to quantify soil erosion through erosion plots, the models used so far for determination the soil erosion are not well accepted. The purposes of this study were to set up a new erosion quantitative method in determination short-term erosion and sedimentation and to develop spatial erosion distribution models. We chose Eu (europium) as tracer atom. Based on the field experiment, positioning soil core Eu (europium) tracer (PSCET) was established. There were 80 cores set to 8 different slope sections. The samples were taken with soil sampler in 1.5 months interval. We further analyzed the data using multiple linear regressions and multiple linear stepwise regressions to model relationships between soil erosion and its factors. PSCET was applied to bamboo field (Deqing county, southeastern of China). The field was 54 m in length and 15 m in width. The experimental results indicated that erosion modulus increased with gradient increasing and ranged from 83.6 to −53.4 t ha yr−1 in different slope sections. Temporal erosion distribution pattern was consistent with rainfall within a year. The 57.0% of annual rainfall (1068 mm) were accumulated in 3 months (June–August) and 80.1% of the annual soil losses were recorded on bamboo field in 1996–1997 (June–August). The statistical data showed that correlations between erosion modulus with rainfall agent of erosion, slope length, and slope degree index were positive; and with plant cover, organic matter contents, and clay particle contents were negative. Our field experiment results strongly suggest that PSCET makes it possible to study spatial erosion and deposition distributions.