Areas with market potential as farm-gates sales inferred from population density (in individuals/km2 or i/km2). Population density was provided by the National Center for Geographic Information and Analysis (NCGIA) from the University of California at Santa Barbara.

Soil texture interpreted in terms of suitability for pond construction. Soil texture data was obtained from the FAO-UNESCO Soil Map of Africa at 1:5 million scale. This dataset includes three soil texture classes: coarse, medium and fine and these are given for the dominant soils of each association and refer only to the upper 30cm.