1. Soil Science Department Jean Lorougnon Guédé University Daloa Côte d’Ivoire
2. University of ThièsÉcole Nationale Supérieure d’Agriculture Thiès Sénégal
3. Life and Environmental Sciences University of California Merced CA USA
4. Geology Department San José State University San José CA USA
5. School of Environment and Natural Resources The Ohio State University Columbus OH USA
6. Laboratoire National de Recherche sur les Productions Végétales Dakar Sénégal