The Jóor (Dior) soils of Senegal's Peanut Basin are inherently low in organic matter, limiting yields of millet and other crops and threatening the food security of smallholders. Focus groups and interviews were conducted in eight villages to characterize the site-specific fertility management by farmers in the Peanut Basin. Results of the qualitative survey revealed that farmers base management decisions on a series of fertility indicators that include type, color, and texture of soil, presence of vegetation, and productivity in previous years. In an effort to equalize fertility across the field, farmers amend areas they classify as less fertile with decomposed manure + household waste from the family sėntaare (traditional pile) or with compost from managed piles. On-site measurements of soil in areas of fields amended with compost or sėntaare material revealed significant increases in peanut and millet growth over unamended areas, but little difference between the effects of compost and manure. Similarly, chemical analysis revealed increased ECEC and nutrient concentrations (K, Mg, and Al) in soils amended with compost or manure. Similarities in the chemical characteristics of compost and sėntaare material suggest that development workers could emphasize improved pile management rather than promoting more labor-intensive composting. Keywords: compost, indigenous knowledge, local soil classification, manure, nutrient cycling, semi-arid West Africa