Soil erosion—crop productivity relationships for six Alberta soils

Water and wind erosion are major soil degradation forces on the Great Plains of North America but their effects on soil productivity are not well quantified. Six experimental sites were established in Alberta in 1990–1991 to ascertain the effects of simulated erosion on soil productivity. Incremental depths of soil (0, 5, 10, 15, and 20 cm) were removed with an excavator. Highly significant relationships were found between the depth of desurfacing and subsequent spring wheat yields, showing that simulated erosion drastically reduced soil productivity. Treatment effects at an irrigated site followed the same trends as the dryland sites, illustrating that top-soil loss cannot be offset by adequate soil moisture. Our results show that the loss in returns caused by topsoil removal depends on (a) the particular depth increment of topsoil removed by erosion; (b) soil type; and (c) whether the soil is dryland or irrigated.