The effects of grazing management on perennial ryegrass (Lolium perenne L.) herbage mass and persistence in south-eastern Australia

The effect of various grazing management treatments on newly sown and degra ded perennial ryegrass pastures was studied at 6 different locations in the temperate high rainfall zone of southern Australia, as part of the Tempera te Pasture Sustainability Key Program. The sites were located at Hamilton ( 2 sites, 1 grazed by cattle, 1 grazed by sheep) and Cavendish, western Vict oria, Victor Harbor (Delamere), South Australia, and Ross and Parattah in T asmania. Grazing management treatments significantly influenced the ryegras s mass and persistence of the pasture, but effects were not always consiste nt across sites. Autumn closure increased the perennial ryegrass content at Cavendish and Ross, as did the winter and summer closures at Ross. Spring closure increased the perennial ryegrass content at Hamilton, Cavendish and Ross, but decreased it at Parattah, as did the summer closures at Parattah and Delamere. Fodder conservation decreased the ryegrass only at Parattah. At the Hamilton sheep site, and at Ross, mob stocking increased the ryegra ss content, as did increased superphosphate treatments at Hamilton. Rotatio nal grazing at Cavendish and Delamere increased the ryegrass content, as di d the late spring or a late summer closure with a short autumn deferment at Cavendish and Ross, but both these treatments decreased ryegrass at Paratt ah. The treatments that had a negative effect at Parattah may have had a po sitive effect on cocksfoot at that site, creating competition for, and decr easing the ryegrass content. At most sites, treatments that included some s pelling during spring to foster seed shedding, and spelling again in the fo llowing autumn to encourage germination seem to have been of benefit to the perennial ryegrass.