Published online 13 January 2009 | Nature | doi:10.1038/news.2009.17

News

Digital soil map for Africa launched

Map will help farmers to improve crop production.

The map covers 42 African countries.CIAT

Soil scientists are developing the first ever digital soil map of Africa, covering 42 countries south of the Sahara. The map will provide up-to-date information on the health and properties of the soil, helping farmers and policymakers to improve degraded soils and increase crop production.

The map will be made from satellite measurements of soil nutrients, moisture and organic matter. These data will be combined with samples taken over the next four years at 60 randomly chosen sites across sub-Saharan Africa, where researchers on the ground will measure the soil's chemical and physical properties and its organic content.

Using this information, scientists can predict soil properties at places they have not sampled, checking their models by comparing predicted soil properties against actual measurements. The map will also incorporate existing soil maps and information on geology and climate.

A farmer in Malawi, for instance, could use the map — which will be freely available online — to find out how much fertilizer, and of what type, his or her land needs. The project is also looking into sending information to mobile phones, which are very common in Africa.

The map will divide the continent into squares that measure 90 metres x 90 metres — giving 100-times greater resolution than the best current maps of African soils, say scientists.

Valuable update

"This is a quantum leap," says Alfred Hartemink, a soil scientist at ISRIC — World Soil Information, an independent foundation in Wageningen in the Netherlands, and one of the scientists leading the project. "With these maps we can now produce quick, cheap and accurate information."

Poor knowledge of soil conditions has hampered efforts to improve African soils, which are some of the most depleted on Earth, Hartemink says. Existing soil maps are incomplete and date from the 1960 and 1970s, he says.

"This project will benefit farming families in Africa by showing how they can reverse declining soil fertility, a major reason for slow growth in the region's agricultural productivity during recent decades," says Namanga Ngongi, president of the Alliance for a Green Revolution in Africa based in Nairobi, Kenya, a partnership to promote sustainable agriculture in Africa.

The mapping project, called the African Soil Information Service, is launched today at the Tropical Soil Biology and Fertility Institute in Nairobi, which is leading the initiative. The institute is part of the International Centre for Tropical Agriculture, a non-profit research body funded by international organizations and private foundations.

The African initiative is the first phase of a bigger project to develop a global soil map, called GlobalSoilMap.net, which will be launched in New York next month. 

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