An experiment was conducted to examine the effect of fertilizer (triple superphosphate) and stocking rate on animal and pasture productivity on Sumba Island, Eastern Indonesia. The Ongole heifers used in the 1-year experiment gained weight during the wet season and lost weight during the dry season at stocking rates of 0·5 and 1·0 head/ha when grazing native Themeda pasture. The dryseason weight loss was arrested when a prepared seed-bed pasture, which contained 21 % Siratro at the start of the experiment was grazed at a stocking rate of 1·5 head/ha. Increasing the stocking rate to 2·5 head/ha on this pasture resulted in an increase, in the weed component of the pasture from 12 to 84% in 1 year.
The mineral content of plucked samples of pasture indicated that levels of Ca and Mg were generally adequate for growing beef cattle and that Na supplementation would be beneficial. Plant N concentration was below 1·5% in the Themeda and Imperatacomponent but above this in the legume at the prepared seed-bed site. The P concentration in the Themeda and Imperata was always below the 0·24 % level required by cattle, as it was in the legume at the end of the experiment.
The introduction of herbaceous legumes into pastures under set stocking conditions can lead to pasture instability.