The effect of nitrogen fertilizer on the seasonal production of irriagted perennial grasses in coastal New South Wales

Abstract

The seasonal productivity of eight perennial grasses at three nitrogen levels was measured in small pure-grass swards at Badgery's Creek, New South Wales. Highly significant differences in seasonal productivity were found between nitrogen levels in all four seasons, and between cultivars in summer, autumn, and winter. The response of the grasses to nitrogen was slightly greater at the high than at the medium level of nitrogen application in all seasons, and was highest in spring (about 40 lb of dry matter per lb of applied nitrogen) and lowest in mid-winter (about 8 lb/lb). Tall fescue was the most efficient responder to nitrogen in late summer and early autumn, Kangaroo Valley ryegrass in late autumn and late winter, and Currie cocksfoot in mid-winter. At a high level of nitrogen, the dry matter produced by Kangaroo Valley ryegrass and Currie cocksfoot in the late autumn to early spring period, the period of greatest feed shortage, was nearly as great as that produced over a similar period by sod-sown oats in earlier experiments at Badgery's Creek.