@INBOOK {SANGINGA:2001, title = {Nitrogen contribution of promiscuos soybeans in maize-based cropping systems}, author = {Sanginga, P. and Okogun, J. and Vanlauwe, B. and Diels, J. and Carsky, R. and Dashiell, K. }, editor = {Tian, G. and Ishida, F. and Keatinge, J. }, year = {2001}, type = {Sustaining soil fertility in West Africa}, pages = {157--177}, publisher = {Soil Science Society of America (SSSA); American Society of Agronomy}, }