Assessment of soil redistribution and spatial pattern for a small catchment in the black soil region, Northeastern China: Using fallout ²¹⁰Pb_ex

Soil erosion greatly reduces soil fertility. Quantification of soil erosion is required to effectively implement soil conservation practices. This study used the ²¹⁰Pb_ex measurements to assess long-term rates and spatial pattern of soil redistribution in an agricultural catchment in the black soil region, Northeastern China. A total of 61 sampling cores were collected from the catchment, where ¹³⁷Cs has been previously used to study medium-term soil redistribution rates. The potential use of ²¹⁰Pb_ex was validated through using ¹³⁷Cs measurements in our previous study and other methods. ²¹⁰Pb_ex-based soil redistribution rates ranged from -106.5 to 166.9tha^-1yr^-1 with a mean value of -3.9tha^-1yr^-1. The net erosion rate for the entire catchment was -8.3tha^-1yr^-1, which is much higher than the tolerable soil erosion rate. The spatial pattern of soil redistribution was investigated based on the ²¹⁰Pb_ex measurements. The correlations between the rates of soil redistribution and slope gradient and curvature were not significant at the 0.05 risk level. Although the shelterbelts could greatly affect spatial pattern of soil redistribution, ca. 78% of the eroded soils were lost per year from the agricultural catchment and soil erosion has accelerated in the last few decades. Integrated soil conservation measures are urgently required to effectively control soil loss in the black region of Northeastern China.