CHANGING SEASONAL GROWTH OF PASPALUM PASTURES BY OVER-DRILLING RYEGRASS AND WHITE CLOVER CLOVER

Volunteer summer-growing paspalum is often present in dairy pastures of northern New Zealand. When paspalum becomes the dominant grass winter/spring pasture production is reduced. This creates management problems on seasonal dairy farms because cow feed requirements and milkfat production are highest in winter/spring. This paper gives data from a current experiment at Ruakura Agricultural Research Station in which Roundup herbicide was used to provide a competitlon-free environment for the overdrilling of cool-season pasture species. Herbicide rates of 6, 4, 2 and 0 l/ha were applied in autumn 1965 before overdrilling a mixture of Ellett ryagrass and Grasslands Kopu white clover. A fifth treatment was the original pasture which was not sprayed or overdrilled. High rates (4-6 I/ha) of Roundup completely elimmated paspalum from the pasture and immediately reduced the white clover to a low proportion (less than 10% of dry matter). The sprayed and overdrilled pastures have remained ryegrass dominant over the duration of the experiment. In 1985 and 1966, winter/spring production from the new ryegrass dominant pastures were significantly better than from the original paspalum dominant pasture. The implications of the noticeable increase in paspalum in the renewed pastures are discussed. Keywords: pasture renewal, pasture renovation, Roundup herbicide, pasture botanical composition, seasonal pasture productlo".