Early impact of topsoil removal and soil amendments on crop productivity

Wind erosion remains a common form of soil degradation on the semiarid northern Great Plains. This study was conducted to ascertain the effects of erosion on soil productivity and methods for its amelioration. Incremental depths (0, 5, 10, 15, and 20 cm) of surface soil or cuts were mechanically removed to simulate erosion at four sites (three dryland, one irrigated) in southern Alberta in 1990-1991. Three amendment treatments (N + P fertilizer, 5 cm of topsoil, or 75 Mg ha(-1) of feedlot manure) and a check were superimposed on each of the cuts. In the first three years (1990-1992), there were highly significant relationships between cut and spring wheat (Triticum aestivum L.) yield parameters (midseason biomass, grain and straw yield, head density, tillering capacity, and grain elemental concentrations). Removal of 20 cm of topsoil reduced grain yield by 53% (an average of 11 site-years). Manure proved the best amendment for restoring productivity (e.g., an 11-site-year average increase of 158% in grain yield on the 20-cm cut), with N + P fertilizer being the feast effective (40% grain yield increase on the 20-cm cut). Manure's ability to supply crop P, Mg, Mn, and Zn may partially explain its positive effect. Topsoil addition was intermediate in its restorative powers (89% yield increase after 20 cm topsoil removal). The study reinforces the need to prevent erosion and indicates that application of livestock manure is an option for restoring soil productivity in the short term.