Tiller population and tissue turnover in a perennial ryegrass pasture under hard and lax spring and summer grazing

Abstract

Plots of perennial ryegrass were grazed by sheep at 3 to 4-week intervals under hard (postgrazing herbage mass 1000 kg DM/ha) and lax (2000 kg DM/ha) management from October 1986 to August 1988. In early December 1987 treatments on half the plots were switched, giving 4 combinations of hard and lax grazing with 4 replicates. Tiller populations were consistently higher under hard than lax grazing. Net pasture and leaf production rates were also generally higher under hard grazing, because higher senescence losses compensated for higher rates of pasture growth under lax grazing. The switch from hard to lax grazing in late spring gave a transient increase in net pasture production, but the switch from lax to hard grazing at the same time resulted in a high tiller appearance and enhanced net leaf production over the summer. Management strategies to take advantage of this latter effect in pasture systems are discussed briefly. Keywords Tiller population, tissue turnover, grazing management, perennial ryegrass