@INBOOK {KANG:1990, title = {Long-tern fertilizer trials on alfisols in West Africa}, author = {Kang, B. and Balasubramanian, V. }, year = {1990}, type = {Transactions, 14th International Congress of Soil Science, Vol. IV, 12-18 Aug 1990}, pages = {20--25}, address = {Kyoto, Japan}, }