Effects of erosion on soil quality and productivity of a field near Saskatoon
de Jong, E.
Soil erosion has been identified as a major contributor to soil degradation on the Prairies. An 84 ha cultivated watershed near Saskatoon was selected to study the variability in erosion and deposition. 137Cs deposited mainly in the early 1960's was used as a tracer for soil movement. Soil erosion ranged from 35 t/ha/yr in small tributaries to the main channel, to 4 t/ha/yr or less on upper slope areas which occupied 60 % of the area. High rates of soil deposition were found in. upland depressions and in the main channel. The net soil loss from the basin was 2340 t or about 1 t/ha/yr. Seventy to 80% of the lost soil was retained ahead of a dam in the coulee leaving the field. It is estimated that the eroding areas of the field (approximately 77 ha) suffered an organic C loss of 275 t from the early 1960's to mid 1980's. Preliminary estimates indicate that about 215 t of organic C were deposited in the upland depressions and the main channel inside the field boundaries. Estimates of the organic C trapped in the coulee are in the order of 50 to 90 t. Further sampling will be needed to resolve the discrepancy between estimates of organic C lost from the field, and organic C trapped, in the coulee. Based on approximate relationships between soil depth and yield potential, it is expected that the production of about one quarter of the eroding area is adversely affected by erosion when other growing conditions are good.
Soils and Crops Workshop