Maïga-Yaleu S.B., Chivenge P., Yacouba H., Guiguemde I., Karambiri H., Ribolzi O., Bary A., Chaplot V.
Laboratory of Analytical Chemistry, Radiochemistry and Electrochemistry (LACARE), University of Ouagadougou, Burkina Faso; Laboratory of Hydrology and Water Resources, International Institute of Water and Environmental Engineering (Institute 2iE), Burkina Faso; Department of Training and Research, Regional Center AGRHYMET, Niamey, Niger; School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Rabie Saunders Building, Scottsville, South Africa; Géosciences Environnement Toulouse (GET), UMR 5563, IRD-Université de Toulouse, UPS (OMP), CNRS, 14 Av Edouard Belin, Toulouse, France; Laboratoire d'Océanographie et du Climat, Expérimentations et approches numériques, UMR 7159, 4, place Jussieu, Paris, France
Maïga-Yaleu, S.B., Laboratory of Analytical Chemistry, Radiochemistry and Electrochemistry (LACARE), University of Ouagadougou, Burkina Faso, Laboratory of Hydrology and Water Resources, International Institute of Water and Environmental Engineering (Institute 2iE), Burkina Faso, Department of Training and Research, Regional Center AGRHYMET, Niamey, Niger; Chivenge, P., School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Rabie Saunders Building, Scottsville, South Africa; Yacouba, H., Department of Training and Research, Regional Center AGRHYMET, Niamey, Niger; Guiguemde, I., Laboratory of Analytical Chemistry, Radiochemistry and Electrochemistry (LACARE), University of Ouagadougou, Burkina Faso; Karambiri, H., Department of Training and Research, Regional Center AGRHYMET, Niamey, Niger; Ribolzi, O., Géosciences Environnement Toulouse (GET), UMR 5563, IRD-Université de Toulouse, UPS (OMP), CNRS, 14 Av Edouard Belin, Toulouse, France; Bary, A., Laboratory of Analytical Chemistry, Radiochemistry and Electrochemistry (LACARE), University of Ouagadougou, Burkina Faso; Chaplot, V., School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Rabie Saunders Building, Scottsville, South Africa, Laboratoire d'Océanographie et du Climat, Expérimentations et approches numériques, UMR 7159, 4, place Jussieu, Paris, France
Soil surface crusting influences water infiltration and runoff but its impact on soil organic carbon (SOC) losses by sheet erosion is largely unknown. Because there are different mechanisms of sheet erosion, from raindrop detachment and transport by raindrops interacting with flow (RIFT), to detachment and transport by flow, that require a certain slope length to be operative, this study examined the impact of slope length on SOC and nutrient losses. Field experiments were conducted on crusted soils in the Sahel region of Africa. Three replicates of micro-plots (1m×1m), plots (10m long×5m width) and long plots (25m×6m) were installed for each crust type in the area (structural, STRU; desiccation, DES; gravel, GRAV; and erosion, ERO) and followed for each rainfall event in the 2012 rainy season. Sediment, SOC content in sediments and selected nutrients (NO3 -; PO4 3-) in the runoff were analyzed to evaluate the annual losses by sheet erosion. SOC losses decreased significantly with increasing slope length from 0.24gCm-1 on micro-plots to 0.04gCm-1 on plots and to 0.01gCm-1 on long plots and similar trends were observed for NO3 - and PO4 3- losses. This suggested a strong scale dependency of sheet erosion with the efficiency of transport by saltation and rolling by RIFT decreasing significantly with increasing slope length, by 6 folds in average between 1 and 10m, with values between 1.8 on DES crusts and 19 on STRU crusts. These results on the relationship between soil crusting and sheet erosion should be further used to mitigate against the loss of SOC through the implementation of improved soil conservation techniques, as well as to improve soil erosion and/or SOC models. © 2014 Elsevier B.V.