Soil quality and productivity responses to simulated erosion and restorative amendments

Abstract

There is little quantitative information on the interrelatedness of soil erosion, soil quality and soil productivity. A simulated erosion approach was used to quantify erosion and amendment effects on soil quality and subsequent productivity at four southern Alberta sites. Zero, 5, 10, 15 and 20 cm of topsoil were removed (cuts) at each site and subplots were amended with N + P fertilizer, 5 cm topsoil, 70 Mg ha-1 cattle manure or left unamended. Wheat (Triticum aestivum L.) yields in the 2-yr study on the non-amended check plots showed significant correlations with organic C at three of the four sites, and extractable P and inorganic C at all four sites. While manure was the best amendment for enhancing soil productivity, the magnitude of its effect depended on the organic C content of the recipient soil. At an organic C content of 8 g kg-1 on the Lethbridge Dryland site, manure addition increased crop yield by 1.75 Mg ha-1, compared with only 0.27 Mg ha-1 at an organic C content of 15 g kg-1. Our results affirm the benefits of soil management practices that reduce erosion risk, preserve soil quality and sustain productivity.