SOTER and WISE-based soil property estimates for Southern Africa

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A harmonized set of soil property estimates been developed for Southern Africa using a 1:2M Soil and Terrain Database (SOTERSAF) and auxilliary soil profiles held in the WISE database.   

The land surface of Southern Africa has been characterized using 4022 unique SOTER units, corresponding with 6099 polygons. The major soils have been described using 941 profiles, selected by national soil experts as being representative for these units. The associated soil analytical data have been derived from soil survey reports. These sources seldom hold all the physical and chemical attributes ideally required by SOTER. Gaps in the measured soil profile data have been filled using a step-wise procedure that uses taxotransfer rules based on profile data held in WISE.  

Property estimates are presented by FAO soil unit for fixed depth intervals of 0.2 m to 1 m depth for: organic carbon, total nitrogen, pH(water), CECsoil, CECclay, base saturation, effective CEC, aluminium saturation, CaCO3 content, gypsum content, exchangeable sodium percentage (ESP), electrical conductivity of saturated paste (ECe), bulk density, content of sand, silt and clay, content of 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  in MS Access format  and have been linked to the 1:2M SOTERSAF map using GIS.