Loss of soil resources from water-eroded versus uneroded cropland sites under simulated rainfall

Soil erosion is widespread in agricultural lands of the US Corn Belt. The objective of this study was to examine the impact of antecedent erosion on loss of soil under laboratory simulated rainfall. The soil was obtained from the surface layer of eroded (ER) and uneroded (UN) sites within a conservation agro-ecosystem in central Ohio, USA. Air-dried soil was subjected to a rainfall simulation for 60 min (dry run), and to another simulation (wet run) 24 h after the dry run. In the dry run, the cumulative water runoff, sediment yield, and soil organic carbon loss were higher in ER (12.3 L/m2, 169.3 g/m2, and 5.6 g/m2, respectively) than in the UN (7.3 L/m2, 22.6 g/m2, and 0.9 g/m2 respectively). An opposite trend was observed for the cumulative water infiltration (0.9 and 3.9 L/m2, respectively). In the wet run, despite a similar cumulative water runoff from the two erosional phases (20.1 and 19.6 L/m2 in ER and UN respectively), sediment yield and soil organic carbon loss were higher in ER (484.4 g/m2, and 16.3 g/m2 respectively) than in the UN (146.6 g/m2, and 5.3 g/m2 respectively). Also for the wet run, an opposite trend was observed for the cumulative infiltration (0.8 and 5.8 L/m2 respectively). This study suggests that past erosional processes increase the susceptibility of remaining soil to accelerated erosion.