Reactive transport modelling the oxalate-carbonate pathway of the Iroko tree; Investigation of calcium and carbon sinks and sources

•Reactive transport approach to simulate soil and root processes.•The Iroko sequesters carbon as calcite in soils via the oxalate carbonate pathway.•Oxalate oxidation induces local soil pH change from acidic to alkaline.•Weathering and root processes crucial in amassing Ca for calcite precipitation.