Agriculture In Southern Africa Research Articles

A tenfold increase in the Orange River mean Holocene mud flux: implications for soil erosion in South Africa

Soil erosion poses a major threat to sustainable agriculture in southern Africa but is difficult to quantify. One measure of soil erosion is the sediment flux of rivers. The Orange River is the principal source of sediment to the western margin of South Africa with an estimated mean mud flux over the last 11 500 years (the Holocene epoch) of 5.1 (3.2—7.4) million metric tons/year (Mt/yr). A total of 43 gigatons (Gt; 1015 g) representing 72% of the Holocene mud flux has accumulated on the shelf in the Orange River prodelta and mudbelt, a clayey fine-silt deposit focused on the inner to middle shelf. Only 8% (5 Gt) of the mud flux occurs in Holocene calcareous ooze on the slope. Comparison of the clay to mud ratio of offshore deposits with Orange River suspended sediment and catchment soils indicates that 20% (11 Gt) of the Holocene mud flux has been lost as clay beyond the margin. The Orange River mud flux prior to the building of large dams (1930—1969) is ten times greater than the mean Holocene mud flux and is reconciled with estimates of soil erosion within the catchment. A tenfold increase in the Orange River mud flux implies up to a hundredfold increase in total soil erosion depending on the extent of mud storage over periods of decades to centuries within the catchment. Erosion has shifted from areas of high relief and rainfall of the Drakensberg escarpment during the Holocene to intensely cultivated lands of low relief having moderate to high rainfall in the eastern catchment and to a lesser extent, grazing areas of the southern Orange River catchment.

Exploring Growth Linkages and Market Opportunities for Agriculture in Southern Africa

The heterogeneity of southern African countries offers the region a unique opportunity to exploit agricultural potential and trade opportunities through regional integration. We analyze the implications of such opportunities using a regional general equilibrium model. We find that growth in South Africa benefits the region's low-income countries through increased demand for their agricultural exports, higher prices that stimulate production for domestic markets, and slower decline of prices from increased production. Agricultural productivity growth, however, is necessary for low-income countries to take advantage of South Africa's growth. The largest benefits for low-income countries result from rising productivity of grain and livestock production.

Long-term effects of improved legume fallows on soil invertebrate macrofauna and maize yield in eastern Zambia

Though improved fallows have been widely promoted as low-input technologies suitable for soil fertility replenishment in smallholder agriculture in southern Africa, their interaction with soil invertebrates has not been studied. In the present study we compared the population of soil macrofauna in maize grown in gliricidia (Gliricidia sepium), leucaena (Leucaena leucocephala), Leucaena diversifolia, sesbania (Sesbania sesban) and acacia (Acacia anguistissima) and continuously cropped monoculture maize. The objectives of the study were to determine (1) the effect of the type and length of fallows on soil macrofauna communities and functional groups, and (2) the long-term effect of legume fallows on maize yield. The number of invertebrate orders per sampling unit was significantly influenced by the type of fallow but not by the length of fallow period. Maize grown in legume fallows had more numbers of invertebrate orders than monoculture maize. Among the soil invertebrate macrofauna, centipede and millipede populations were significantly influenced by fallow type. The density of earthworms varied with both the type and length of fallow practice. Earthworm populations under maize grown in gliricidia fallows were significantly higher than those under fully fertilized monoculture maize. The population densities of other invertebrate orders and functional groups did not significantly differ between maize grown continuously in monoculture and in legume fallows. The highest maize grain yield (3.0–6.0 t ha−1) was recorded in fully fertilized monoculture. Maize grown in gliricidia and leucaena fallows consistently gave 2.0–4.0 t ha−1 throughout the study period, while maize grown without fertilizer yielded less than 2 t ha−1. These legumes produced 0.4–2.9 t ha−1 of re-sprout biomass annually, which released nutrients contributing to higher maize yields over a long period of time. It is concluded that these legume fallows can improve maize yields in addition to their positive impact on the diversity and functions of soil invertebrates.

HIV/AIDS and Agriculture in Southern Africa: What Difference Does It Make?

HIV/AIDS and Agriculture in Southern Africa: What Difference Does It Make?

Appropriate Plant Nutrient Management for Sustainable Agriculture in Southern Africa

Sustainable agriculture encompasses three facets ecological sustainability, economic sustainability, and socioeconomic sustainability. The three facets of sustainability are interlinked. This article focuses on soil fertility management in relation to these three facets of sustainable agriculture. Appropriate input levels are determined by the nature of the natural resources, especially soil and climate, and benefit to cost ratios. The appropriate type of input for a specific situation is determined by the levels of deficiency of specific nutrients and the type of fertilizer material available. Application of appropriate levels and types of inputs is critically important in many areas that are marginal in regard to climate and/or soil, which perforce have to be cropped in many developing countries. Several factors, such as land tenure systems, infrastructure, input subsidies, price control, etc., strongly influence the inputs made and the sustainability of agriculture. Results from decades of fertilizer experiments by the FAO in various countries and various other case studies are used to illustrate the principles involved. The need for appropriately equipped soil and plant analysis laboratories in developing countries is emphasized.

Food policy and agriculture in southern Africa

Food policy and agriculture in southern Africa

The Effects of Increased Earnings from Traditional Agriculture in Southern Africa

The Effects of Increased Earnings from Traditional Agriculture in Southern Africa

Agriculture in Southern Africa: Shaping the Future, Annual Conference of the Agricultural Economics Association of Southern Africa, 4 ‐ 5 May 1987, Johannesburg

Agriculture in Southern Africa: Shaping the Future, Annual Conference of the Agricultural Economics Association of Southern Africa, 4 ‐ 5 May 1987, Johannesburg

A comparison of the contribution and relative performance of agriculture in Southern Africa

This paper analyses the contribution and relative performance of agriculture on the Southern African subcontinent. Agriculture and the total economy, sectoral division of agricultural production and trends in agriculture and food production are discussed. From the analysis it is obvious that the developed commercial agricultural sector of South Africa is the dominant force in the subcontinent's agriculture. This sector is, however, at present hampered by various socio‐economic and financial problems. The paper concludes with certain policy recommendations regarding developing traditional agriculture. Potential co‐operation and interaction are also commented upon.

Agriculture in Southern Africa

Agriculture in Southern Africa