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PATCHINESS OF FORAGE RESOURCES IN TIME: HOW STOCKING RATE

AGGRAVATES THE EFFECTS OF DROUGHT ON STOCK FARMING

 

TC Meyer / CD Blom

Grootfontein Agricultural Development Institute

Private Bag X529

MIDDELBURG 5900

 

The climate of arid lands is characterized by low rainfall that is poorly distributed in both space and time. Droughts occur regularly and wide annual variation in rainfall is to be expected. As a result, plant productivity may vary six fold or more between favourable and unfavourable seasons. Therefore, any scheme to graze arid lands must be flexible in order to cope with the extremely variable conditions that exist.

Farmers can adopt one of two strategies to adapt to variable forage supply. On the one hand, they can vary their stock numbers according to forage availability. The second strategy requires that conservative stocking rates be applied. This implies that during above average years, available forage is not utilized fully, and some reserve forage is left for years of below average forage production.

Results obtained from a stocking rate trial at Grootfontein during the disaster drought of the 1992/93 season clearly indicate the appropriateness of the second management strategy. It indicates that forage availability, as reflected by animal production, was influenced by stocking rate. Fodder shortages was experienced more than 20 weeks earlier at the high than at the lower stocking rate. As a result, meat production at the lower stocking rate was more than double that obtained at the high stocking rate. The management implications of the results for the farmer, are discussed.

 

Published

Arid Zone Ecology Forum 1994