P.A. PIETERSE and N.F.G. RETHMAN

Department of Plant Production and Soil Science, University of Pretoria, Pretoria, Republic of South Africa

Abstract

The influence of soil acidity and nitrogen fertilisation on the DM yield of Pennisetum purpureum (napier grass) and two Pennisetum hybrids, known as Bana and Green-gold, was investigated on the Hatfield Experimental Farm of the University of Pretoria, Republic of South Africa. The pH(H₂O) of top soil on the experimental site was 4.2. Two other pH levels (5.6 and 6.5) were created by applying different rates of Ca(OH)₂. Four levels of N fertilisation (0, 100, 200 and 400 kg/ha) were compared using 3 replications per treatment combination. The results indicated that napier grass was not well adapted to the site, but both hybrids were persistent and drought-resistant and compared favourably with other pasture grasses adapted to this region. None of the pastures in this trial was sensitive to acidity in the top soil. The optimum level of N application was 150 kg/ha/yr, similar to that for other sub- tropical grass pastures in the region.