Examining the Sense and Science Behind Ghana's Current Blanket Fertilizer Recommendation

Despite advancements in geographic information systems mapping, remote sensing, and soil testing technology that can help in approximating soil fertility requirements at specific sites, Ghana, like most countries in Africa, continues to use blanket fertilizer recommendations based on soil tests and experiments that are over a decade old. This could be one of the main reasons why the country continues to record dismal crop productivity growth even after the reintroduction of the fertilizer subsidy program in 2008. If farmers are applying the wrong type and amount of fertilizer on their fields, it is likely that crop productivity growth will continue to stagnate. However, the Council for Scientific and Industrial Research, with support from the Alliance for a Green Revolution in Africa, the Commonwealth Agricultural Bureau International, and the International Fertilizer Development Corporation, has engaged in a concerted effort to promote location-specific fertilizer recommendations. This paper was written to help bolster the case and present visual evidence demonstrating why it is important to seriously consider spatial soil fertility variability in Ghana and to promote area-specific fertilizer recommendations. Using geostatistical analysis of soil samples collected from farmer plots in three districts (Tamale Municipality, Savelugu-Nanton, and West Mamprusi in northern Ghana), the paper analyzes spatial variations in soil fertility. The results clearly show that there are variations in soil pH, organic matter content, and available phosphorous even at the community level, supporting the need for Ghana to seriously consider location-specific fertilizer recommendations