Predicting the Temporal Relationship between Soil Cesium-137 and Erosion Rate1
- R. G. Kachanoski and
- E. de Jong2
A model was developed that predicts the amount of 137Cs remaining in soil as a function of time and erosion rate. The model accounts for atmospheric deposition, radioactive decay, tillage dilution, and erosion transport of 137Cs, as well as seasonal differences in 137Cs deposition and erosion rates. The model was used to estimate minimum resolution of erosion estimates based on detection limits and accuracy of 137Cs measurement by gamma spectroscopy, as a function of time and erosion rate. The analysis showed that under Saskatchewan conditions, changes in 137Cs at a given site can be used to estimate erosion rates between 0.5 and 10 kg m−2 yr−1 with reasonable precision, provided the sampling interval is at least 15 yr. The relationship of fraction of 137Cs lost vs. erosion as predicted by the model was compared with other methods being used. The model was used to estimate erosion from selected Saskatchewan soils where 137Cs levels were measured in 1966 and again in 1981. Erosion rates calculated with the model varied from 1 kg m−2 yr−1 for a sandy loam soil in continuous forage to 19 kg m−2 yr−1 for a similar soil in a crop-fallow rotation. Erosion estimates using the model were higher than those calculated by assuming that soil loss was directly proportional to 137Cs loss, especially when 137Cs loss was high.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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