Surface erosion assessment in New Zealand using caesium-137

The 137Cs technique has provided the first quantitative, medium-term data on rates of soil redistribution by surface erosion on both cropland and rangeland in New Zealand. Research has also provided data on natural short-range variability of 137Cs in uneroded soils, and a technique for independently estimating 137Cs input values from rainfall. The greatest research need remains the development of robust, accurate calibration procedures for converting 137Cs measurements to rates of erosion. Emphasis has been on application of the technique to provide field-based data on erosion rates, with limited research to further develop the technique. This paper summarises recent research in these two areas