ISRIC Report 2003/04: Soil data derived from SOTER for studies of carbon stocks and change in Jordan (GEFSOC Project)

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Batjes NH, Rawajfih Z and Al-Adamat R
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This report presents a harmonized set of soil parameter estimates for Jordan, developed to permit modelling of soil carbon stocks and change at the national scale. The Soil and Terrain Data base for Jordan (JORSOTER), at scale 1:500 000, compiled by the former National Soil Map and Land Use Project, formed the basis for the current work.
Twenty eight SOTER units have been mapped for Jordan, corresponding with 69 soil components. The major soils have been described using 48 soil profiles, selected by national soil experts as being representative for the country. The associated soil analytical data have been derived from soil survey reports.
Gaps in the measured soil profile data have been filled using a step-wise procedure which includes three main stages (Batjes 2003): (1) collate additional measured soil analytical data where available; (2) fill gaps using expert knowledge and common sense; (3) fill the remaining gaps using a scheme of taxotransfer rules.
Parameter estimates are presented by soil unit for fixed depth intervals of 0.2 m to 1 m depth for: organic carbon, total nitrogen, pH(H2O), CECsoil, CECclay, base saturation, effective CEC, aluminum saturation, CaCO3 content, gypsum content, exchangeable sodium percentage (ESP), electrical conductivity of saturated paste (ECe), bulk density, content of sand, silt, clay, coarse fragments, and available water capacity. 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.
The current parameter estimates should be seen as best estimates based on the current selection of soil profiles and data clustering procedure. Taxotransfer rules have been flagged to provide an indication of the possible confidence in the derived data. Results are presented as summary files and can be linked to the 1:500 000
scale SOTER map for Jordan in a GIS, through the unique SOTER-unit code.
The secondary data set is appropriate for studies at national scale. Correlation of soil analytical data, however, should be done more rigorously when more detailed scientific work is considered.
Keywords: soil parameter estimates, Jordan, environmental modelling, soil carbon, WISE database, SOTER database, secondary data set