The influence of grazing on the botanical composition of an irrigated pasture at Lawes, south-east Queensland

Abstract

An irrigated mixed pasture of short rotation ryegrass (Lolium multiflorium x L. perenne) Phalaris tuberosa L. and white clover (Trifolium repens L.) was grazed at six- and eight-weekly intervals and at six-weekly intervals with two summer grazings omitted. Yields of the components were measured for three years. Short rotation ryegrass contributed very little to yield after its first flush of growth following sowing. At the end of the three years, short rotation ryegrass in the six-weekly grazing treatment was contributing six per cent of the total yield, two per cent in the eight-weekly treatment, and one per cent in the rested treatment. Resting for eighteen weeks in summer favoured the development of Phalaris and hence reduced clover dominance. At the end of three years, Phalaris was contributing forty-four per cent of the total yield in the rested treatment and twenty-three and thirty-seven per cent in the six-weekly and eight-weekly grazing treatments.