SOIL-EROSION - CROP PRODUCTIVITY RELATIONSHIPS FOR 6 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 i n 1990-1991 to ascertain the effects of simulated erosion on soil prod uctivity. Incremental depths of soil (0, 5, 10, 15, and 20 cm) were re moved with an excavator. Highly significant relationships were found b etween the depth of desurfacing and subsequent spring wheat yields, sh owing that simulated erosion drastically reduced soil productivity. Tr eatment effects at an irrigated site followed the same trends as the d ryland sites, illustrating that top-soils loss cannot be offset by ade quate soil moisture. Our results show that the loss in returns caused by topsoil removal depends on (a) the particular depth increment of to psoil removed by erosion; (b) soil type; and (c) whether the soil is d ryland or irrigated.