1. Definitions
(a) The semi-arid zone is defined as the zone with an annual growing period of 90-180 days. The correspondence between this definition and other bioclimatic classifications is illustrated in the Appendix to these terms of reference which is a copy of Figure 2.3 of Hans Jahnke's (1982) book on Livestock Production Systems and Livestock Development in Tropical Africa.
(b) Mixed farming systems, for present purposes, are understood to exist where both livestock and crop production take place within the same locality, and where ownership of land and livestock are integrated. However, where specialised livestock production takes place in the same locality as crop production, subject to resource-sharing (e.g. grazing of residues) but under separate ownership, such systems may be included in the study.
2. The problems
Research in the past has tended to concentrate on specialised systems of livestock or crop production. The livestock component of mixed farming systems has often been treated as secondary or insignificant. But:
(a) There is now an increasing awareness of the risks to environmental degradation in the semi-arid zone. This justifies a wholistic approach to mixed farming systems and their degrading or sustaining impact on the environment.(b) Recent drought experience in Africa has re-emphasized the complementary economic roles of livestock and crops in contributing to household viability, especially during crop failures, when livestock ownership supports smallholder resilience by diversifying economic options.
(c) The search for appropriate technologies of intensification to improve productivity in the semi-arid zone has generated interest in indigenous systems of smallholder farming with livestock and trees as integral components, as well as new technologies of agro-forestry-with-livestock. The cost of inorganic fertilizers in semi-arid environments means that alternatives, including nutrient cycling through livestock, have to be taken seriously.
However, the diversity of mixed farming systems is considerable, and insufficient is known of the nature and scale of contemporary change and stress. There is need for a review and taxonomy of mixed farming systems with respect to the role of the livestock component and its environmental impact (increased vulnerability to degradation or enhanced sustainability).
3. Geographical scope
The geographical scope of the study will be the semi-arid zones of all countries in sub-Saharan Africa between the Tropics including Mauritania, Sudan, Botswana, Mozambique, Madagascar and Namibia, but excluding countries touching the Mediterranean, and the Republic of South Africa.
4. Inventory
The study will review accessible published and "grey" literature on mixed farming systems in the semi-arid zone using ethnicity as an initial frame of reference; and inventory, to the extent possible with the accessible literature, for each system:
(a) territorial extent and organisation
(b) environmental properties;1 average rainfall
2 length of growing season
3 average slope
4 dominant soil type or soil type ratio
5 principal vegetation communities in natural pastures
6 surface and well water distribution and seasonal availability(c) livestock types
(d) functional role of livestock in the system
(e) tenure and livestock ownership
(f) farming intensity and livestock density
(g) best estimates for human and livestock populations.
The systems will be summarised by country with respect to (g). As far as is found practicable, the ethnically labelled systems will be subdivided or combined on the basis of major differences or similarities in the properties (a)-(f) above, and a set of functionally homogeneous systems identified.
5. Review
The study will review information relating to environmental trends, risks, and stresses, including where available evidence of:
(a) changes in the territorial extent and organisation of the systems;(b) trends in farming intensity, grazing management, livestock numbers and density;
(c) increasing commercialisation of the livestock component;
(d) livestock management practices potentially or actually contributory to environmental degradation;
(e) environmental degradation (soil erosion or fertility decline, vegetational change, dune formation).
A theoretical evaluation of potential environmental risk will be attempted by relating key management properties of mixed farming systems to published maps of erosion and desertification hazard, estimates of human carrying capacity, and data on rainfall trends since about 1965.
6. Taxonomy
The study will classify mixed farming systems according to the most appropriate criteria selected from section 4 above, and (if practicable) on an environmental vulnerability sustainability scale. The human and livestock populations and territorial extent of each class will be estimated.
