Summary
This continental-scale study of 1,601 soil samples across sub-Saharan Africa identified geochemical properties—particularly oxalate-extractable metals and exchangeable calcium—as equally important as climate variables in controlling soil organic carbon concentrations. The findings suggest that key SOC controls operate similarly across tropical, subtropical and temperate regions, despite differences in soil development history, though the relative importance of geochemical factors varies by weathering status and soil pH.
UK applicability
The study's findings on geochemical controls on SOC may have limited direct application to UK temperate soils, which typically have different weathering status and mineralogy than the sub-Saharan African soils studied. However, the methodological approach and the principle that geochemistry influences SOC stabilisation alongside climate may inform UK soil monitoring and carbon sequestration assessments.
Key measures
Soil organic carbon concentration (g kg⁻¹); oxalate-extractable aluminium and iron; exchangeable calcium; soil pH; soil texture; mean annual temperature; aridity index
Outcomes reported
The study identified the relative importance of soil properties and climate variables in explaining soil organic carbon (SOC) concentrations across 1,601 soil samples from 17 sub-Saharan African countries. Key predictors included geochemical properties (oxalate-extractable metals and exchangeable calcium) and climatic variables, which together explained approximately two-thirds of SOC variation.
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