Tactical versus continuous stocking in perennial ryegrass-subterranean clover pastures grazed by sheep in south-western Victoria. 2. Ryegrass persistence and botanical composition

A 4-year field experiment was carried out in south-western Victoria to determine whether tactical stocking might improve perennial ryegrass (Lolium perenne L.) persistence and prime lamb production, compared with the more common practice of continuous stocking. Tactical stocking consisted of variable-length summer, autumn and winter rotations and continuous stocking in spring. The 2 grazing strategies were compared on 2 contrasting pastures: an upgraded pasture, sown with newer cultivars of perennial ryegrass and subterranean clover (Trifolium subterraneum L.) with 26 kg phosphorus/ha.year, and a more typical naturalised perennial ryegrass pasture receiving 6 kg phosphorus/ha.year. Paddocks were grazed by Border Leicester x Merino ewes, which were mated to a terminal sire to lamb in September. The effects of the grazing systems and pasture treatments on ryegrass persistence and pasture botanical composition are presented in this paper. The perennial ryegrass component of the sward decreased from an average mass of 1000 kg dry matter/ha on the upgraded pasture and 400 kg dry matter/ha on the typical pasture in spring 1996 to 100 kg dry matter/ha and