Evapotranspiration studies on<i>themeda triandra</i>under field conditions: A study in lysimeter methodology

Abstract

Abstract In the semi‐arid regions of South Africa, the efficiency of water use by natural grazing plants is important and can be used to evaluate the production potential of comparative grasses. Hydraulic non‐floating lysimeters were designed and tested under field conditions and indicated that with accurate calibration for temperature and moisture, dependable data on the evapotranspiration of a cover of Themeda triandra could be recorded over long periods. Under a Themeda grass cover an average of 1,26 1 of water was lost by evapotranspiration for each 1 g DM produced over the period December 1972 to May 1973. The merits of the home‐made drum lysimeters are discussed in terms of costs (R35 per unit) and constancy of readings over two and a half years.