Land cover, extent, and properties of arenosols in Southern Africa

Arenosols cover about 13% in Sub-Saharan Africa and are widely spread in the southern part of the continent. Knowledge about the spatial distribution, properties, and land cover of Arenosols can be used to design programs to alleviate the major constraints for agricultural production. This article reviews the importance of Arenosols in eight countries of Southern Africa (Angola, Botswana, Lesotho, Mozambique, Namibia, South Africa, Swaziland, and Zimbabwe). Estimates of their extent are based on SOTER databases. The total extent of Arenosols in the eight countries is 169 million ha: extensively in Angola and Botswana (>50% of total land area) but also in Zimbabwe, South Africa, and Mozambique (>15% of total land area). About 26.3 million ha of Arenosols are under forest; 104.7 million ha under savannah and 3.5 million ha is desert and dunes. In total, 6.5 million ha of Arenosols are under agriculture cropland, most of which is located in Angola, Botswana, and South Africa. Arenosol topsoils in Namibia and South Africa are mostly alkaline but in Angola and Zimbabwe, the average topsoil pH of Arenosols is below 6. Organic carbon is uniformly low in Arenosols of Southern Africa and rarely exceeds 10 g kg(-1). Higher C contents are found in soils with slightly higher clay content, whereas higher C levels are also associated with higher cation exchange capacities (CECs). The low CEC and low water-holding capacity necessitates the addition of organic manures to increase agricultural production on Arenosols in Southern Africa.