Abstract
Established plots of 10 different pasture species were trodden at different rates nine times between December 1958 and October 1959, with mature Romney sheep. Treading generally reduced measured herbage yield, the heaviest treading causing the greatest reduction. Reduction in tiller number appeared to be the main cause of the reductions in yield. Under heavy treading, plant tolerance order, from most to least, was: perennial ryegrass (Lolium perenne L.), Poa pratensis L., Poa trivialis L., short-rotation ryegrass (Lolium perenne L. × Lolium multiflorum Lam.), browntop (Agrostis tenuis), white clover (Trifolium repens L.), timothy (Phleum pratense L.), cocksfoot (Dactylis glomerata L.), red clover (Trifolium pratense L.), and Yorkshire fog (Holcus lanatus L.). Under moderate treading the order was P. trivialis, perennial ryegrass, P. pratensis, short-rotation ryegrass, white clover, timothy, browntop, cocksfoot, red clover, and Yorkshire fog.