@PROCEEDINGS {KANG:1991, title = {Soil constraints for sustainable upland crop production in humid and subhumid West Africa}, author = {Kang, B. and Gichuru, M. and Hulugalle, N. and Swift, M. J. }, booktitle = {Soil constraints on sustainable plant production in the tropics: proceedingsof the 24th International Symposium on Tropical Agriculture Research, Kyoto, Japan, 4-16 August 1990}, series = {Tropical agriculture research series, No. 24}, year = {1991}, publisher = {Tropical Agriculture Research Center}, address = {Tsukuba, Japan}, isbn = {0388-9386}, }