Production of natural grassland in the central Orange Free State in relation to climate.

Abstract

In order to plan a livestock enterprise it is imperative to know the production potential of the natural grassland. Grassland production is determined mainly by climate and soil, provided reasonably sound management practices are employed. It is thus evident that effective planning must necessarily depend heavily on a reliable knowledge of the climate/plant/soil interaction. Photosynthesis is the source of primary production in grassland. A simulation model Putu 2 computes the potential total production, environmental limiting factors as well as the daily water balance, taking rainfall into account. Environmental limitation and total dry matter production for Bloemfontein was computed over three growing seasons. The results show that fairly accurate estimates of total production are possible with the Putu 2 simulation model especially during years of normal and above normal rainfall. The soil water status computed for Themeda triandra dominated veld agrees well with the results obtained in field trials. The limiting environmental factors for three growing seasons were computed with moisture representing by far the greatest limitation on production.

Keywords: bloemfontein; climate; dry matter production; environmental factors; field trial; grassland; limiting factor; management; model; photosynthesis; primary production; production potential; rainfall; simulation model; soil; soil water; south africa; themeda triandra; water balance