Soil nutrient concentrations under Acacia albida and Kigelia africana trees growing in Zambezi riverine woodlands were compared with soils in the open, beyond tree canopies. Concentrations of N, C, P and K were higher under tree canopies. Concentrations of Ca and Mg were unchanged. Soils were slightly more acid under A. albida trees relative to open soil, but were less acid under K. africana. Soil P concentration was higher under K. africana than under A. albida. Otherwise, the two species had similar effects on soil fertility. Despite previous claims, A. albida is probably no more efficient at increasing soil fertility than other savanna trees.
