South Africa - part II
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|5. THE PASTURE RESOURCE
The main forage resource for livestock in South Africa is rangeland grazing. In the higher rainfall zones crop residues are a very important feed supplement in the communal areas during the dry season when range grazing is scarce, while in the commercial areas some farmers plant fodder species. Irrigated fodder production is very limited owing to the lack of suitable soils and water supplies in the commercial areas. In times of drought, South Africa imports fodder from neighbouring countries.
5.1 Range grazing
It is well recognised that rainfall is the primary determinant of forage production, and a number of workers in Africa have demonstrated linear relationships between annual rainfall and primary production within the rainfall limits experienced in South Africa. These relationships can be simplified to straightforward expressions of kilograms of annual dry matter production of forage per millimetre of annual rainfall (Le Houerou, 1984).
An above-ground biomass production model based on the concept of rain-use-efficiency has been developed (Palmer 1998) and applied to rangeland. The resultant map for commercial production is provided (Figure 7). The production may be converted to carrying capacity by assuming a daily requirement of 11.25 kg dry matter per large stock unit, and a use factor of 0.4 (Le Houerou, personal communication). The use factor may decline to 0.2 in mesic grasslands with high C:N ratios.
There have been a number of debates on range grazing in southern Africa during the past 80 years, with the focus changing from the earlier perspectives of rangeland change due to desertification to more recent debates on the role of global climate change on the rangeland resources. Instead of re-phrasing the content of these debates, we have chosen to point readers at the appropriate of published text which synthesize these debates. Wherever possible, we point the reader to an electronic copy of the original text.
Following the earlier work of Ellis and Swift (1988) on the disequilibrium/equilibrium concept, there have been numerous articles which attempt to define the processes which lead to degradation of rangeland in southern Africa (Behnke and Scoones 1993, Behnke, Scoones & Kerven 1993, Galvin & Ellis 1996).In response to this debate, Illius & O'Connor (1999) have asked "When is grazing a major determinant of rangeland condition and productivity?" and conclude
Following a detailed description of the impact of humans on the grazing resources of South Africa, Hoffman (1997) reports:
On the role of megaherbivores in the exacerbation of the bush encroachment problem, Hoffman (1997) reports:
On the subject of "overgrazing", Hoffman (1997) reports:
As cultivation of new lands is a common practice and one which has a major impact on rangeland, it is pertinent that some of the debate is presented. Hoffman (1997) summarises the impact of human as follows:
Following a detailed surbvey of degradation patterns in South Africa for the National Desertification Audit, Hoffman & Ashwell (2000) conclude:
5.2 Introduced legumes and fodders
A number of sub-tropical pasture legumes and fodder plants have been screened at various sites from 100700 mm annual rainfall. Probably the most successful example of introduced legumes has been the use of lucerne (Medicago sativa) , annual medics (M. polymorpha and A truncatula) and annual clover (Trifolium sp.) into the grain production systems of the Western Cape. Here the commercial grain producers (wheat, barley, oats) use these species as lay crops to elevate soil nitrogen every 2-3 years. These crops reduce the risk of grain production, and at the same time provide forage for the small stock industry.
Range re-inforcement is conducted on a large scale in the commercial dairy regions of the country. Favoured grass species include Pennisetum clandestinum (kikuyu), Panicum maximum, Digitaria eriantha, while the legumes such as silver leaf (Desmodium spp) are oversown into natural rangeland.
Foggage production in South Africa is important in commercial beef and dairy production systems. Graziers use a wide range of commercially available local and imported grasses and legumes. The performance of growing beef steers grazing foggaged dryland Pennisetum clandestinum (kikuyu) pastures and given limited access (3 h d-1) to Leucaena leucocephala cv. Cunningham (leucaena) was better than that of steers grazing only kikuyu foggage during autumn and early winter (Zacharias et al 1991). Animals grazing leucaena performed better and gained 24.8 kg per animal more, over 90 days, than those on kikuyu alone. There is concern about the risk of leucaena becoming an invasive alien in the humid coast, and further encouragement of the use of this and other potentially aggressive species (e.g. Lespedeza sericea) has been discouraged until further evaluation has been carried out.
Investigations to determine whether frosted Kikuyu could supply quality foggage than natural pasturage in sourveld area during the winter months revealed that this grass was characterised by a crude protein content of 8 - 10% in the winter months. The performance of animals grazing such frosted Kikuyu was highly satisfactory (Rethman & Gouws, 1973). Sheep performance and patterns of herbage utilization were determined in two grazing trials involving different amounts and quality of kikuyu foggage. Wether lambs maintained livemass whereas dry ewes and wether lams both lost 8-10% of their initial mass, irrespective of differences in foggage quality. Grazing capacity was proportional to the yield of foggage and some 50% of the total herbage was utilized. The estimates of quality indicated that a higher level of utilization would have resulted in poorer sheep performance (Barnes & Dempsey1993).
5.3 Dryland fodder
Dryland fodder production is only possible in the higher rainfall regions of the country. The principal form of dryland fodder is cereal crop residues, and these make an important contribution to livestock diets in communal areas during the dry season. Some communal area farmers collect and store at least part of their residues to feed to selected animals such as milk cows and draft oxen, but most of the fodder is utilised in situ.
The cultivation of rainfed crops in South Africa is widespread, occurring in both commercial and communal land-use systems. The most significant commercial grain producing areas are the "maize triangle" of the central highveld, the wheat growing region of the south western Cape and the maize growing regions of central Kwa-Zulu Natal. Maize is widely preferred as the staple food in the communal areas, but millet and sorghum are more reliable crops except in the highest rainfall zones. National cereal production (roughly 80% maize, 16% wheat and 4% other including millet and sorghum) fluctuates considerably from year to year according to rainfall. Production has varied from a low of 5 044 000 Mt in the drought year of 1991/92 to a record high of 15 966 000 Mt in 1993/94.
In the drier central and western farmers commonly have small areas of drought tolerant fodder crops (Table 7) as drought reserve for exceptional circumstances.
Table 7. Exotic species which are used for fodder during exceptional circumstances.
5.4 Irrigated fodder
There are some eighty species of commercially available species and cultivars which are used in South Africa (Klug & Arnott 2000). Lucerne (Medicago sativa) is the main purpose grown irrigated fodder in South Africa, and is grown under irrigation throughout the country. Ryegrass (Lolium multiflorum and L. perenne) is cultivated on a large scale for pastures in the dairy industry. Many other species and numerous cultivars are available commercially and are provided in detail by Bartholomew (2000).
5.5 Imported fodder
In times of drought, the South Africa government traditionally assisted farmers in obtaining fodder by providing subsidies. According to the new drought policy (National Department of Agriculture, 1997), the fodder subsidies have been terminated in order to encourage farmers to build up their own forage reserves and to discourage them from retaining excessive stock numbers. Nonetheless, it is likely that some commercial farmers, and probably the government, will continue to import fodder in extreme drought conditions.
Table 8. Commercial cereal production for South Africa from 1992-2000 (x 1000 tons).
5.6 Constraints to pasture and fodder production and improvement
The principal constraints to pasture and fodder production in communal areas are:
The principal constraints to pasture and fodder production in commercial areas are:
|6. OPPORTUNITIES FOR IMPROVEMENT OF FODDER RESOURCES
There is formal certification of pasture/fodder seed in South Africa. South African seed merchants produce 16 Mt of forage seed per annum for sale locally (14.7 Mt) and export (1.3Mt). Total sales during 2000 were dominated by oats (4.4 Mt), forage sorghum (2.0 Mt), lupens (1.95Mt), triticale (1.55 Mt), annual rye grass (1.5 Mt) and teff (1.0 Mt).
With the long-term goal to preserve germplasm (in most cases, seeds) of the entire South African flora, the ARC-Range and Forage Institute's Genetic Resources Division in Pretoria focuses at present on preservation of seeds of plant species of economic importance. A wide variety of South African pasture grasses, e.g. of the genera Anthephora, Brachiaria, Cenchrus, Cynodon, Panicum, Pennisetum, Setaria and Stipagrostis are included in the current accessions.
One of the most important sources of funding for range improvement has come from the commercial sector which is involved in the rehabilitation of disturbed areas. The mining industry is required to rehabilitate dis-used mines, and have funded a number of projects to identify suitable genetic material for this purpose. The need to make these rehabilitated areas once again available for animal production has ensured that pasture species are favoured in this process. Favoured species for the selection of suitable material include members of the genera Panicum, Eragrostis, Cynodon and Cenchrus. Similarly, the revegetation of road verges, which is funded through the National Transport Commission, provides support for the collection and evaluation of grass species suitable for road verge stabilization. Although this does not directly affect forage species, it does provide funds for the establishment of collections of germplasm which can be used to identify possible forage plants. A dis-advantage of this process has been that genotypes of selected species have been spread throughout South Africa, impacting negatively on the genetic integrity of the indigenous flora.
The need to satisfy the requirements of the developing farmer has encouraged the selection of multi-purpose species which are suitable for both human and animal consumption. In this instance, the cow pea (Vigna unguiculata), has been tested and improved to provide cultivars which are acceptable to both humans as a food source and as a valuable forage source to livestock.
The market for turf grass in South Africa has grown rapidly since the advent of democracy, as more of the national budget is spent on the provision of sport facilities for previously dis-advantaged communities. Once again the commercial sector has become a major source of funds to access and evaluate grass cultivars suitable for turf (mainly Cynodon and Pennisetum).
In the research sector, efforts have been made to identify species suitable for forage production in arid and semi-arid areas. Both breeding and selection has been successful in the improvement of Anthephora sp.
|7. RESEARCH AND DEVELOPMENT ORGANIZATIONS AND PERSONNEL
7.1 Institutional structure
The National Department of Agriculture within the Ministry of Agriculture and Land Affairs is the key institution dealing with forage resources. The National Department of Agriculture is divided into five directorates, one of which deals directly with rangeland and pasture resources. The Directorate Land and Resource Management is responsible for the implementation of the Conservation of Agricultural Resources Act 43 of 1984. This act empowers the head of the directorate to intervene when the agricultural resources of the country are threatened. Prior to 1994 this act was used to subsidise the provision of fencing, erection of new water provision points, the purchase and transport of supplementary fodder during exceptional circumstances, and the clearing of all weeds (alien and indigenous).
Each of the nine provinces also has a section or directorate which deals with rangeland and pasture research.
South Africas National Agricultural Policy states the main objective to be improvement of research in natural resource management (Anonymous 1996). On a project basis, pasture science related programmes deal with rangeland reclamation, carrying capacity, agro-forestry and rangeland management systems. Examples of individual on-going projects related to rangeland and pasture science may be found at the ARC web site.
The National Department of Education maintains seven agricultural colleges and carries out topic-oriented, formal training courses. All courses are certified by one of the tertiary training institutions.
Botanical research relating to rangeland is also conducted by the National Botanical Institute of the Ministry of Environmental Affairs and Tourism. Outside of government, the most significant organisation involved in rangeland research is the Agricultural Research Council's Range and Forage Institute, which conducts research on rangeland and pasture resources. Research direction in the ARC-RFI is determined by the needs of the National Department of Agriculture and Land Affairs, as well as other research clients. The Grassland Society of Southern Africa (GSSA) is the professional organization representing the discipline in South Africa. The GSSA maintains a full-time secretariat for its members, organizes an annual congress at various localities around the sub-continent, and has published a peer-reviewed journal (African Journal of Range & Forage Science) annually since 1966.
The key organisations/individuals and their current areas of activity/interest with relevance to pasture science are as follows:
Directorate Land and Agricultural Resource Managment,
National Department of Agriculture & Land
Affairs, Private Bag X120, Pretoria 0001.
Mr Bonga Msomi, Director, Directorate Agricultural Land Resource Management: range management, bush encroachment, range rehabilitation
Department of Environment Affairs and Tourism,responsible for reporting on the state of South African rangelands for the International Conventions (Convention for the Combatting of Desertification, Biodiveristy Convention)
Agricultural Research Council - Range & Forage
InstitutePrivate Bag X05, Lynn East,0039 South Africa.
Dr A. Aucamp, Director, ARC - Range & Forage Institute
Dr R. Ellis, Head, ARC-RFI Genetic Resources Division: germplasm collection of indigenous flora and dryland crop and fodder species
Prof B. Huntley, Director
Prof. G. Smith, Deputy-Director: maintaining national herbarium
Dr MC Rutherford, Co-ordinator, VEGMAP Project: revising the vegetation map of South Africa
Provincial Department of Agriculture
Fort Cox Agricultural College
of Southern Africa
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For information on pasture and fodder production and management:
For information on South African flora:
Prepared by Tony Palmer and Andrew Ainslie in May 2002; livestock data updated by S.G. Reynolds in August 2006.