Effects of frequency and height of defoliation on the production of a Persian clover-annual ryegrass sward

Abstract

An experiment established the effects of frequency and height of defoliation on the production of an irrigated Persian clover (Trifolium resupinatum)- annual ryegrass (Lolium rigidum) sward. Five intervals of defoliation (from 4 to 12 weeks) were superimposed on 2 heights of defoliation (to ground level and to 4 cm above ground level) in a split-plot design. Total harvested yields ranged from 7.52 to 11.94 t DM/ha and varied according to defoliation management. Except for the very short defoliation intervals, defoliating to the higher level was less productive than defoliating to ground level. There were wide seasonal variations in the effect of treatment. In general, quality of the harvested herbage was relatively constant for much of the year, but in spring the effects of frequency and height of defoliation were evident. At this time, all chemical characteristics indicated that herbage quality declined with maturity of the sward. Optimum defoliation management will depend on both the quantity and quality of herbage produced. This will depend on animal requirements.