Last update: November 24, 2010 10:47:06 AM E-mail Print



PCV du Toit

Grootfontein Agricultural Development Institute, Private Bag X 529, MIDDELBURG, 5900


Large parts of the Kalahari is encroached by Rhigozum trichotomum. Apart from being woody and not grazeable to any extent, it renders the surrounding area unsuitable for the survival of perennial grasses by drying out the soil in large circles around each shrub. Contiguous circles then have no soil protection in the form of perennial herbaceous vegetation. "Driedoring" can be successfully controlled, enhancing the chances of survival of perennial grasses which soon start spreading and thickening up and, thereby raising the grazing capacity of the land.


"Driedoring" was treated with the herbicide Molopo (active ingredient: tebuthiuron) at 1.8 kg/ha, on the farm Gnous.


After only two years there has been a dramatic increase in the grass cover and an increase of 8 times in the grazing capacity, which is however, still some 50% lower than the grazing capacity norm and that of good veld in the area. Perennial grasses such as the Boesmangrasses; Stipagrostis ciliata, S. obtusa and Eragrostis lehmanniana have come back as a result of the higher availability of moisture to the herbaceous plants after the "driedoring" has been killed and their water extraction ability curtailed. It is possible to reclaim degraded Kalahariveld by the application of Molopo to the "driedoring". Despite the relatively high cost of Molopo, this action is deemed economic, when seen in the light of the much higher grazing capacity obtained after treatment, after only two years.