This study is based on the work of Mensah Bonsu, Department of Soil Science, School of Agriculture, University of Cape Coast, Ghana.
The study benefited from the contributions of P. Heffer, International Fertilizer Industry Association (IFA), K. Isherwood (consultant FAO), J. Poulisse and T. van den Bergen (FAO).
The background cover photograph is from the FAO Mediabase: FAO/18309/C. Cenini. The other photographs from the FAO Mediabase are pepper: FAO/20967 (no author) and cocoa: FAO/17254/L. Withers. The photograph on cassava was provided by EcoPort (International Institute of Tropical Agriculture Annual Report 1998).
