Southern Africa has a total land area of 6.8 million km2, of which almost 33 per cent is covered by forest, 21 per cent is desert, and the remaining natural habitat is largely savannas and grasslands. Rainfall in the subregion ranges from 50mm/yr in the arid deserts of Botswana, Namibia and South Africa, to more than 1000mm/yr in the equatorial forests of Angola, Malawi, Mozambique and northern Zambia. In most areas, rainfall is largely seasonal, falling over a period of just a few months, often in the form of intense thunderstorms or showers. Where vegetation cover is reduced, this can lead to higher rates of soil erosion. Likewise, most of the sub-region experiences high variability in rainfall, and frequent or prolonged periods of flooding and drought. Grazing lands currently cover 49 per cent of the area, predominantly in savannas and grasslands and, especially, in the drier countries where forest cover is lower (FAOSTAT 2001). Permanent crops and arable lands cover slightly less than 6 per cent of the land area, and are predominantly rain-fed, except in South Africa, where irrigation potential is relatively well developed.
The proportion of the southern African population employed in agriculture in 1970 was 71 per cent. In 1980, it was 64 per cent and, by 1990, it was 60 per cent (World Bank 2001). Proportions varied, however, from 87 per cent in Malawi to 14 per cent in South Africa (World Bank 2001). The major crops include maize, wheat, tobacco, tea, cashew nuts, sugar cane, coffee and cotton, and these contribute significantly to GDP and to exports. In Tanzania, agriculture contributes up to 50 per cent of GDP and 50 per cent of export earnings (Government of Tanzania 2001). Livestock production is particularly important, accounting for approximately 30 per cent of agricultural earnings. South Africa's agricultural exports totalled US$2 464 million in 1997, and Zimbabwe's reached US$1 157 million (World Bank 2001). In Malawi and Mozambique, agriculture accounts for approximately 35 per cent of GDP, but less than 10 per cent in mineral-rich countries, such as Botswana and South Africa (World Bank 2001).
Small-scale agriculture and pastoralism are widely practised in southern Africa, although the value of these practices is not reflected in national accounts. For example, in Tanzania, approximately 3.8 million households practise small-scale farming, and roughly 10 per cent of these practise pastoralism or agropastoralism (Government of Tanzania 2001). Although cattle dominate, sheep and goats are extremely important sources of protein, accounting for about 12 per cent of the national meat supplies (Government of Tanzania 2001). In Botswana, approximately 70 per cent of the population lives in rural areas and is dependent on agricultural activities-both rain-fed cultivation of crops and livestock rearing-for their livelihoods (Botswana Agricultural Census Report 1993).