C.J.G. LE ROUX, J.S. SWART, E. OOSTHUYSEN, C. TRETHEWEY and C. PITTAWAY

Döhne Agricultural Development Institute, Stutterheim, Republic of South Africa

Abstract

A model to estimate the yield of Coastcross 2, a cynodon hybrid, at Bathurst in the Eastern Cape Province, Republic of South Africa was developed to determine the most profitable fertilisation rates, corresponding yields and margins at a range of rainfall factors and opportunity costs. The model uses nitrogen application rate, soil phosphorus status and rainfall as predictor variables. At current price ratios, the most profitable fertilisation rates are far below those needed for maximum yields. The results indicated a surprisingly high phosphorus fixation rate in the soil.