Valuable soil data collected during decades of soil survey campaigns in sub-Saharan Africa are now easy to download from a new database compiled by ISRIC – World Soil Information.The Africa Soil Profiles Database, version 1.0, contains legacy soil data for over 12,000 geo-referenced soil profile records from 37 countries. The compilation is part of the Africa Soil Information Service (AfSIS), an international programme that analyses information related to the African soil and its management. Access to soil data is badly needed to help resolve major issues such as food security.
ISRIC collected the legacy soil profile records from over 300 data sources, ranging from digital databases, books, reports and articles. The researchers converted the data into a common standard and parsed them using routine quality rules and cleaning. Previously, this data would only have been accessible through dispersed sources and would not be standardized, hindering efforts to make them shareable and usable.
‘These primary soil data are a first step in the production of new-generation soil property maps for sub-Saharan Africa,’ explains ISRIC researcher Johan Leenaars. AfSIS project leader, Markus Walsh, states: ‘This database is working out to be a real information treasure and a great test bed for analyses.’ AfSIS is already using the database for digital soil mapping of Malawi and Nigeria.
In the new database, geo-coordinates have been specified for each of the 12,000 soil profile records. Terrain descriptions have been provided for the majority of records and profiles have been classified for over half of the records. Separate tables contain as many as 50 soil properties, including sand-silt-clay content, organic carbon content and pH. The properties have varying degrees of completeness and are attributed to on average 4 layers per profile.
The database is searchable. ‘Suppose users want to know which soil profiles within a distance of 100 km around Ouagadougou contain over 200,000 kg/ha of organic carbon,’ continues Leenaars. ‘Now they can find this information easily. Users can also find our quality assessments – some records are considerably more reliable than others.’
There are areas, especially in Central Africa, for which there are still hardly any data points. Leenaars, who did most of the work with the help of his colleague at ISRIC Ad van Oostrum, estimates that 5 to 10 percent of all legacy profile data have now been entered in the new database. More data points – legacy and new – will help towards the creation of increasingly accurate soil maps in coming years as part of the worldwide GlobalSoilMap programme.
ISRIC is now developing subsequent versions of the Africa Soil Profiles database, in which partner organizations can contribute data. Support is being sought to further facilitate this collaborative initiative. The newest version (1.1) of the database (MArch 2013) contains a total of over 16,500 profile records of which over 15,000 are georeferenced, from over 450 data sources.