Savanna grassland soils are not very fertile. The nutrients in the soil are found near the surface as they come from decayed organic matter (vegetation) from the previous growing season. This organic matter decays rapidly due to the high temperatures.
Soils tend to be red in colour due to their high iron content. The diagram below shows the different horizons, or layers, of soil in savanna grassland. Plant roots cannot penetrate the hard 'pan' layer in the B-horizon, or subsoil. This restricts vegetation growth.