SOTER and WISE-derived soil property estimates for Senegal and The Gambia (SOTWIS ver. 1.0)

• A 1:1M scale Soil and Terrain Database for Senegal and The Gambia (SENSOTER, ver 1.0), developed in cooperation with the Institut National de Pédologie, Dakar (more) provided the basis for this study.
   
• The land surface of the study area has been characterized using 149 unique SOTER units, corresponding with 2242 polygons. The major soils have been described using 56 measured profiles, selected by national soil experts as being representative for these units, and 34 synthetic profiles. The associated soil analytical data have been derived from soil survey reports; these sources seldom hold all the physical and chemical attributes required by the SOTER methodology.
   
• Gaps in the measured soil profile data in SENSOTER were filled using a step-wise procedure that uses taxotransfer rules, based on analyses of some 4500 similar soil profiles held in the ISRIC-WISE database, complemented with expert-rules.   
     
• Property estimates in the resulting secondary database (SOTWIS) are presented for 18 soil variables by soil unit for fixed depth intervals of 0.2 m to 1 m depth. These include: organic carbon, total nitrogen, pH(H2O), CECsoil, CECclay, base saturation, effective CEC, aluminium saturation, CaCO3 content, gypsum content, exchangeable sodium percentage (ESP), electrical conductivity (ECE), bulk density, content of sand, silt and clay, content of coarse fragments (> 2 mm), and available water capacity (-33 to -1500 kPa). These attributes have been identified as being useful for agro-ecological zoning, land evaluation, crop growth simulation, modelling of soil carbon stocks and change, and analyses of global environmental change.
       
• Results are presented as summary files; these can be linked to the 1:1M scale SENSOTER map using GIS, through the unique SOTER-unit code.
   
• Download documentation or dataset  (MS-Access and ArcGIS9; Release date: 10 November 2008)
   

             
              SOTER-based soil property estimates for Senegal  and The Gambia (SOTWIS-Senegal)

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