@INBOOK {SOBULO: 1986, title = {Soil properties and crops yields under continous cultivation with different management systems}, author = {Sobulo, R. A and Osiname, O. *}, year = {1986}, type = {Land Clearing and Development in theTropics edited by R. Lal, P. Sanchez and R. Cummings. Rotterdam, A. Balkema}, pages = {363--370}, }