@INBOOK {LYASSE:2002, title = {Options for increasing P availability from low reactive rock phosphate}, author = {Lyasse, O. and Tossah, B. * and Vanlauwe, B. and Diels, J. and Merckx, R. }, year = {2002}, type = {In: Integrated plant nutrient management in sub-Saharan Africa: from concept to practice, edited by Vanlauwe, B., Diels, J., Sanginga, N. & Merckx, R.}, pages = {225--237}, chapter = {17}, publisher = {CABI; International Institute of Tropical Agriculture (IITA)}, address = {Wallingford, UK}, isbn = {0 85199 576 4}, }