Developing digital soil maps covering 42 African countries

28 March 2012. Nature article. African agriculture: Dirt poor. The key to tackling hunger in Africa is enriching its soil. The big debate is about how to do it.
African governments, international donors and scientists all agree that farmers must revitalize their soils. But there is passionate debate about how to do it. Many African governments and agricultural scientists argue that large doses of inorganic fertilizers are the most practical solution. But others, such the Food and Agriculture Organization of the United Nations (FAO) in Rome, are pushing for greener, cheaper solutions, such as no-till farming that conserves soil and 'fertilizer plants' that boost the soil's nitrogen content organically. Researchers report that these latter techniques are beginning to raise yields and improve soil fertility. But farmers are slow to adopt such practices, which require significantly more labour.

An international collaboration of researchers is hoping to improve the use of fertilizers by developing digital soil maps covering 42 African countries south of the Sahara. Started in 2009 with an $18-million grant from AGRA and the Bill & Melinda Gates Foundation to the Tropical Soil Biology and Fertility Institute in Nairobi, the maps will provide up-to-date information on soil properties, derived from satellite measurements and sampling at 60 sites across Africa.

Keith Shepherd, a soil scientist at ICRAF who has worked on the maps, says that the analysis will inform agronomists and agricultural extension services about soil health and what nutrients are lacking. “Until now there was no unbiased sampling at this scale so there was no reliable data on acute problems,” he says.

AGRA is also helping to bring some of Africa's better-quality phosphate deposits into production, which will provide sub-Saharan countries with a cheaper source of locally produced phosphate fertilizer.

Related:

Africa Soil Information Service The Africa Soil Information Service (AfSIS) is developing continent-wide digital soil maps for sub-Saharan Africa using new types of soil analysis and statistical methods, and conducting agronomic field trials in selected sentinel sites. These efforts include the compilation and rescue of legacy soil profile data, new data collection and analysis, and system development for large-scale soil mapping using remote sensing imagery and crowdsourced ground observations.

BBC video: Horizons Business. Video interview with Keith Shepherd. Soil Scientists at The World Agroforestry Centre in Nairobi are working on digital mapping systems to help analyse the quality of the soil across the country, so farmers will know what to grow and when to grow it.

ICRAF video: The World Agroforestry Centre's Global Research Project on Land Health aims to develop and promote scientifically rigorous methods for measuring and monitoring land health,assessing land health risks, and targeting and evaluating agroforestry and other sustainable land management interventions to improve ecosystem health and human wellbeing.