Soil quality attributes, soil resilience, and legacy effects following topsoil removal and one-time amendments

Abstract

Inter-relationships among soil erosion, soil quality, soil resilience, and legacy effects of organic amendments have not been adequately quantified. Topsoil was mechanically removed (cuts) to simulate erosion in semiarid southern Alberta in 1990. Three cuts (0, 10, and 20 cm) superimposed with three one-time (1990 only) amendment treatments (check, N + P fertilizer, and manure) were chosen for this study. In the absence of amendments, light fraction C (CLF) and mineralizable C (Cmin) recovered sufficiently by 2004 to render the cut effect nonsignificant. Organic C (Corg) responded more slowly with the 10-cm cut recovering to the 0-cm cut concentration by 2004, and the 20-cm cut (13.9 g kg−1) remaining significantly lower than the 0-cm cut concentration (16.3 g kg−1) through to 2012. Nitrogen fractions behaved similarly. Among cuts and years (2004 and 2012), C fraction values were 19-27% greater on the manure versus check treatment (17.5 vs. 14.7 g kg−1 for Corg, 1.38 vs. 1.09 g kg−1 for CLF, and 650 vs. 531 mg kg−1 for Cmin) demonstrating a strong legacy effect of manure. Water-stable aggregation exhibited a 22-yr legacy effect of manure. Our findings help quantify soil resilience following major disturbance and legacy effects of one-time manure application under semiarid conditions.