ESTIMATES OF SOIL EROSION AND DEPOSITION FOR SOME SASKATCHEWAN SOILS

Abstract

137Cs from the atmospheric testing of nuclear devices in the 1950s and 1960s was used to estimate soil erosion in eight small basins in hummocky topography. Three basins had not been cultivated since the 1950s and in these 137Cs showed little or no separation according to landscape position. In the cultivated basins, 137Cs increased from the top to the bottom of the slopes reflecting the simultaneous occurrence of soil erosion on the upper slopes and deposition on the lower slopes. The redistribution of 137Cs was least in a cultivated basin where water erosion was minimal. From the 137Cs it was estimated that over the past 20–25 yr the upper slopes in the cultivated basins had lost 20–60 kg soil/m2, whereas the lower slopes had gained 25–80 kg/m2. Some middle-slope positions lost soil, others gained. An attempt to construct 137Cs and soil balances for each of the cultivated basins was only partially successful. The inability to accurately delineate areas of erosion and areas of deposition is probably the major obstacle in calculating accurate balances for the basins. The 137Cs balances did show promise of being able to separate soil losses by wind and water erosion. Key words: Water erosion, wind erosion, 137Cs, deposition, universal soil loss equation