58 Achieving a fair and sustainable trade in devil’s claw (Harpagophytum spp.)there is little perennial grass cover and sparse distribution of shrubs and trees,
an observation confirmed by a recent survey among farmers in Namibia
(Hachfeld 1999). Based on an average yield of 600 g per plant and densities of
2 to 2,000 plants/ha, biomass production of H. procumbens can vary from 120
g to 120 kg/ha air dry weight (Wynberg forthcoming).Harvesting and processing
Methods for harvesting Harpagophytum vary considerably from location to
location and depend to a large extent on the intensity of the operation, the
level of awareness among harvesters and the implements at hand. These factors
in turn are greatly influenced by the levels of organisation among harvesters
and by the presence of extension and support services. Although
Harpagophytum can be harvested at any time of the year, digging tends to be
easier and yields greater during the rainy season, when the sand is moist (Nott
1986). This advantage is offset to some extent by the difficulties experienced
in drying material during the rainy season. Permit conditions introduced by
both Namibia and Botswana confine harvesting to the dry period between
March/April and September/October, a restriction imposed largely to curtail
overharvesting.Figure 2. Distribution of H. procumbens. Data provided by National Herbarium,
Pretoria Computerised Information System (PRECIS)04devilcslaw.P65 58 22/12/2004, 11:04