Influence of stocking rate and grazing systems on available grazing in the northern cape¹

Portion of a Ph.D. — thesis by the senior author

Abstract

The influence of rotational and continuous grazing systems, each applied with four stocking rates, on the above‐ground phytomass of veld was determined over four years.

Grazing systems showed a significant influence on available herbage during one year only. Increased stocking rates brought a progressive decline in above‐ground phytomass. During the fourth season (1980/81) the average grazing pressures at stocking rates of 10 ha, 7 ha, 5,5 ha and 4 ha/Large stock unit were 5 984 kg, 3 417 kg, 2 390 kg and 1 238 kg and 1 238 kg phytomass/Large stock unit, respectively. At the end of the fourth season (July, 1981) there was reserve grazing available on the various stocking rates for approximately 579 days, 337 days, 202 days and 76 days, respectively. The risk of high stocking rates in the marginal rainfall regions, is emphasised.

Uittreksel

Die invloed van wisselweiding en aanhoudende beweidingstelsels, elk met vier beladingspeile, is op die beskikbare bogrondse fitomassa van veldweiding gedurende vier proefseisoene bepaal.

Beweidingstelsels het gedurende die proefperiode van vier jaar slegs in een seisoen ‘n betekenisvolle invloed op die hoeveelheid beskikbare weidingsmateriaal gehad. Die bogrondse fitomassa per hektaar het daarenteen deurgraans progressief verminder soos wat veebelading toegeneem het. Die gemiddelde beweidingsdruk gedurende die vierde seisoen (1980/81) by die onderskeie beladingspeile (10 ha, 7 ha, 5,5 ha en 4 ha/Grootvee‐eenheid) was onderskeidelik 5 984 kg, 3 417 kg, 2 390 kg en 1 238 kg fitomassa beskikbaar per Grootvee‐eenheid. Aan die einde van die vierde seisoen (Julie 1981) was daar na raming by die onderskeie veebeladings voldoende reserwe welding vir onderskeidelik 579 weidae, 337 weidae, 202 weidae en 76 weidae. Die riskantheid van te hoë beladingspeile in die marginale reënvalgebied word beklemtoon.

Additional index words:

• Above‐ground phytomass
• grazing pressure

Notes

Portion of a Ph.D. — thesis by the senior author

Present address: Darling Downs Institute, Toowoomba, Australia, 4350.