SOil and TERrain Digital Database (SOTER)

SOTER aims to establish a World Soils and Terrain Database, at scale 1:5 000 000, containing digitized map units and their attribute data in standardized format. The programme is implemented by FAO, UNEP and ISRIC, under the aegis of the IUSS, in collaboration with a wide range of national soil institutes, since 1986. ISRIC plays a lead role in methodology development and programme implementation. Space Shuttle Radar Topographic Mission (SRTM) digital elevation data are now being used to derive the different landform units and to generate terrain information (more1, more2); soil attribute data are largely derived from legacy  field data. Ultimately, a global SOTER is to replace the FAO-Unesco Soil Map of the World (SMW), the first internationally accepted inventory of world soil resources.

SOTER databases are developed using a uniform methodology, endorsed by  FAO, UNEP and IUSS, using standard input software. They are developed at scales ranging from 1:5 million to 1:500 000, depending largely on the needs of the users.

Gaps in the measured soil profile data are typically filled using consistent pedotransfer rules derived from the WISE soil profile database. The resulting secondary (SOTWIS) data sets are being been used for a wide range of applications, including assessments of impacts of soil degradation on food supply, soil vulnerability to pollution and modelling of soil organic carbon stock and changes at national and regional levels (see publications). The SOTWIS sets are also used as input layers for the FAO-led Harmonised World Soil Database (HWSD), which is being developed further in the framework of the Global Soil Partnership (PDF). Alternatively, the range of soil profiles collated in SOTER are being used to generate the SoilGrids1km product, using digital soil mapping.