THE EFFECT OF SUMMER MANAGEMENT OF PERENNIAL RYEGRASS-DOMINANT SWARDSON PLANT AND ANIMAL RESPONSES IN THE AUTUMN WHEN GRAZED BY SHEEP .1. TISSUE TURNOVER AND SWARD STRUCTURE

An experiment was conducted to compare the effects of the grazing by e wes and weaned lambs on aftermath and previously continuously grazed p erennial ryegrass-dominant swards, at two sward heights (4 and 8 cm) i n the autumn, on changes in structure and growth of the swards. The ex periment had a factorial design, was replicated twice and was conducte d from mid-August to early November with measurements being made on th ree occasions in the autumn, Aftermath swards had lower tiller populat ion densities and lower herbage masses than those that had been previo usly continuously grazed, the differences being greatest in August. On an area basis net growth rates of herbage on aftermaths were lower th an those on previously continuously grazed swards in August and Septem ber but not in October, Growth rates of herbage were higher on the tal ler sward, but the senescence rates were similar at the two sward heig hts. It was concluded that autumn swards may be managed at taller swar d heights than summer swards without increasing senescence of the swar d and a consequent reduction in efficiency of utilization. The effects of previous sward management on tissue turnover in the autumn were no t long lasting.