Soil and Carbon Loss From Five Different Land Uses Under Simulated Rainfall.

Soil and Carbon Loss from Five Different Land Uses under Simulated Rainfall Basant K Rimal* and Prof. Rattan Lal Research Associate and Director, respectively, Carbon Management and Sequestration Center, School of Environment and Natural Resources, The Ohio State University, 210 Kottman Hall, 2021 Coffey Road, Columbus, OH 43210-1085, USA *Corresponding author phone. Tel.: 614-688-4937; Fax: 614-292-7432. E-mail address: rimal.1@osu.edu Abstract Soil erosional processes are influenced by aggregate size and stability, and the stabilization effect of soil organic carbon (SOC) and other cementing agents. Thus relative significance of structural properties and SOC concentrations were studied for soils of the North Appalachian Experimental Watersheds under a range of land uses. Aggregates of 2 – 8 mm size from the 0-10 cm depth were obtained from soil under forest, pasture, no-till with manure (NT+M), no-till without manure (NT-M) and conventional tillage (CT) land use systems. Soil and carbon (C) losses and associated surface runoff and percolation water were measured using rainfall simulator at 5 min interval for one using 8.5 % slope under dry and wet runs. Soil losses under simulated rainfall conditions varied over time and among land use types in both dry and wet runs. Highest soil loss 1547 g/m2 was observed from NT-M, followed by 1342 g/m2 in CT, 963 g/m2 in NT+M, 554 g/m2 in pasture and in 513 g/m2 in forest. Overall soil loss from wet aggregates was higher than those from dry aggregates. Higher soil loss contributed to higher amount of C from soil under all land uses. Yet, general trends of soil loss were similar for dry and wet runs and were in the order NT-M > CT > NT+M > Pasture >Forest land use. While trends were similar, wet run merely increased the amount of soil loss. However, the magnitude of soil loss differed significantly among time intervals (P < 0.01). In dry run, the highest soil loss (0.2 kg/m2) was observed under CT and occurred much earlier over 15 minutes of rainfall than under other land uses. In comparison, the highest soil loss (0.17 kg/m2) was observed in 20 minutes for NT-M, 40 minutes for forest, 45 minutes for NT+M, and 55 minutes for Pasture land uses. In wet run however, the highest soil loss commenced after 10 minutes in all land uses. Surface runoff in dry run, differed significantly (P < 0.01) among CT and other land uses. There was no significant difference in the amount of surface runoff among land uses from wet aggregates (P < 0.05). Percolation loss also varied among land uses. The CT treatment had the lowest percolation followed by that from forest, pasture, NT-M and NT+M land uses. Key words: Rainfall simulation, infiltration, percolation, inter-rill erosion, soil erosion, soil carbon loss, dry and wet aggregates,