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University of KwaZulu-Natal (1988)

Studies of the management of grazing resources on the Makatini Flats and Pongolo River Floodplain

Buchan, Alastair James Charles

Titre : Studies of the management of grazing resources on the Makatini Flats and Pongolo River Floodplain.

Auteur : Buchan, Alastair James Charles.

Université de soutenance : University of KwaZulu-Natal

Grade : Master of Science (MS) 1988

Résumé partiel
Subsequent to the impounding of the Pongolo river in the 1970’s, development of irrigated agriculture on the Makatini flats has been reducing the area of vegetation available for grazing, and flooding patterns on the seasonally inundated Pongolo River Floodplain have been determined by the controlled release of water from the Pongolapoort dam. About 50 000 people live along the 10 000 ha floodplain within the 63 000 ha northern region of the flats which was studied. This population includes 2 970 registered cattle owners who own a total of 19 300 cattle. The objectives of this study were : to gain an understanding of the Makatini pastoral system which would facilitate prediction of the effects of potential developments, including agricultural expansion, modification of floodplain hydrology and changed cattle management practices on the utility value of cattle ; and to provide guidelines for the management of pastoral resources on the Makatini and other traditional African pastoral systems. It was established that the value of cattle cannot be determined without understanding the importance of the subsistence utilities provided and that the value of utilities relative to each other influences the way in which the system is stocked and managed by the local people. The value of all marketed and non-marketed utilities was determined and the implications of the economic evaluation for the identification of management options in African pastoral systems assessed. Despite the "low productivity" of the Makatini system compared to western style ranches, cattle owners receive annual returns worth approximately 100 % of the asset value of their stock. This explains low market offtake rate in this and other subsistence systems. Non-marketed utilities, particularly milk production provide most of the returns to cattle owners. The mean stocking density on the floodplain vegetation was estimated to be three times that of dry-land areas, but only 23 % of all grazing time is spent on the floodplain. Although floodplain forage provides an important supplement to winter grazing, its use is not vital to maintenance of animal condition. The coincident occurrence of an annual "stress period" ; greater acceptability of Echinochloa pyramidalis vegetation as forage ; the absence of floods ; and the reduced use of floodplain fields, results in increased floodplain use in winter to a stocking density approximately ten times that of dry-land areas. How the floodplain hydrology, rainfall and grazing interact with the crop growth rate and quality of E. pyramidalis stands was examined. The forage production potential of E. pyramidalis was found to be higher than that of other floodplain vegetation types and stocking densities of up to 4.5 AU/ha in summer and 2.5 AU/ha in winter are considered possible on the Pongolo floodplain. Echinochloa pastures may become wet and cause scouring if grazed exclusively, but grazing reduces plant moisture content and makes the forage more acceptable. Local pastoral management was found to depend on the collective activities of cattle owners in pursuit of personal needs in a dynamic socio-economic context.

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