@PROCEEDINGS {NANGJU:1975e, title = {Interaction of fertilizer use on cowpea ( Vigna unguiculata (L.) Walp.) and Soybean (Glycine max. (L.) Merill) Nodulation and Nitrogen fixation in the Lowland Tropics}, author = {Nangju, D. and Kang, B. T. and Ayanaba, A. }, booktitle = {Presented at Conference on Biological Nitrogen Fixation in Farming Systems of the Tropics}, year = {1975}, publisher = {IITA}, }