@INBOOK {ABAIDOO:2007a, title = {Evaluation of cowpea genotypes for variations in their contribution of N and P to subsequent maize crop in three agro-ecological zones of West Africa}, author = {Abaidoo, R. and Okogun, J. and Kolawole, G. and Diels, J. and Randall, P. and Sanginga, N. }, year = {2007}, type = {Advances in integrated soil fertility management in sub-Saharan Africa: challenges and opportunities}, pages = {401--412}, publisher = {Springer}, address = {Dordrecht, The Netherlands}, isbn = {978-1-4020-5759-5}, }