Discrepancies about Soil Degradation.

Comments on a report in the March 2002 issue of 'Environment' from David Niemeijer and Valentina Mazzucato about their findings on soil degradation in the Sahel region of West Africa. Discussion of discrepancies highlighted by the authors between their results and earlier work based on modeling and limited field data; Topics of arable land, soil fertility, nutrient losses, and deforestation; Response of the authors to criticism of their methodology.