@PROCEEDINGS {RAO:1980a, title = {Exploiting symbiotic nitrogen fixation for increasing soybean yields in Africa}, author = {Rao, R. V. and Ayanaba, A. and Eaglesham, A. R. J. and Kueneman, E. }, booktitle = {GIAM VI Conference, Lagos, Nigeria, September 1980}, year = {1980}, }