The first detailed digital soil map of sub-Saharan Africa is to be created. The £12m ($17.5m) project will offer farmers in 42 countries a ""soil health diagnosis"" and advice on crop yields.

Scientists from the International Center for Tropical Agriculture (CIAT) will take soil samples from across the continent and analyse nutrient levels.
These will be combined with satellite data to build a high-resolution map, to be disseminated freely to poor farmers by local extension workers.
The interactive online map, known as the African Soil Information Service (AfSIS), will be accompanied by advice on how to tackle soil deficient in nutrients.
It is the first stage of project to build a global digital map - called GlobalSoilMap.net - covering 80% of the world's soils.
The initial four-year program is being funded by a grant from the Bill & Melinda Gates Foundation and the Alliance for a Green Revolution in Africa (Agra).
""From the farmer in the field, right up to to the secretary general of the UN, we need precision soil information,"" said Pedro Sanchez, of Columbia University's Earth Institute, a partner in the project.
""But we do not have this in sufficient detail. ""For example, in the whole of Malawi there is only one fertilizer recommendation for maize - but there are many different soil types.
""While other disciplines, such as climate science, have created detailed digital maps, we are still catching up."" African soils are among the poorest in the world, and many farmers suffer from chronically low-yielding crops.
More than 50% of land in Africa is unsuitable for any kind of cultivated agriculture except nomadic grazing. Of the remaining agricultural land, a large proportion is either moderately or severely degraded.
(Source: BBC)