Hydraulic non-floating lysimeters were used to determine the evapotranspiration (Et) and water use efficiency (W.U.E.) of veld in different successional stages for the period September 1978 to June 1979. In addition runoff of the various successional stages was recorded on runoff plots.Averages of 1,018 litres, 1,258 litres and 1,771 litres of water were lost by evapotranspiration from climax, subclimax and pioneerveld respectively for each gram D.M. produced during the second half of the growing season. The highest Et-losses were recorded during the last week of November, when the grasses were in the reproduction phase.The runoff from the pioneer-runoff plots was 171 percent higher than that of the climax runoff plot. A computer programme was used to fit harmonic curves to the weekly Et/Eo relationship of each successional stage for the 1978/79 growing season.
Keywords: afrikaans; botany; evapotranspiration; grass; grasses; hydraulic non-floating lysimeters; lysimeter; orange free state; runoff; season; south africa; sydenham; university of the free state; veld; water use efficiency