Spring and autumn animal treading effects on pregrazing herbage mass and tiller density on two contrasting pasture types in Ireland

摘要

A perennial ryegrass (Lolium perenne L.)dominated sward on a welldrained soil (Experiment 1) and a creeping bent (Agrostis stolonifera L.)dominated sward on a poorly drained soil (Experiment 2) were subjected to four treading treatments: control (C, no damage), light damage (L), moderate damage (M) or severe damage (S) to quantify the effects on herbage drymatter (DM) production and tiller density. In Experiment 1, treading damage was imposed in spring. In Experiment 2, onethird of the site was damaged in autumn, onethird in spring and onethird in both spring and autumn. Both sites were rotationally grazed after treading treatments. Pregrazing herbage mass was measured eight times in Experiment 1 and seven times in Experiment 2 on each plot, and tiller density was assessed four times in each experiment. In Experiment 1, pregrazing herbage mass was reduced by 30% in S plots at the first harvest after damage, but cumulative pregrazing herbage DM production was not different between treatments (12p"7iu tiu DMiu hap#). In Experiment 2, annual cumulative pregrazing herbage mass was reduced by between 14 and 49%, depending on intensity of treading damage event and season when damage occurred. Tiller density was not affected by treatment in either experiment. A perennial ryegrassdominated sward on a welldrained soil was resilient to heavy treading damage. A creeping bentdominated sward on poorly drained soil requires a more careful grazing management approach to avoid major losses in cumulative pregrazing herbage mass production during wet weather grazing events.