Use of Italian Ryegrass to Increase Feed Production from Dairy Pastures in Northern New Zealand

The effect on pasture production In late winter-early spring was examined by direct drilling Italian ryegrass (Lolilum multiflorum Lam. cv, Concord) into plots previously sprayed with glyphosate or undersowing into existing pasture in autumn 1989 and 1990. Nitrogen fertiliser (25 kg N/ha) was applied to half the area of each plot on 3 occasions during winter. Concord ryegrass was also direct drilled after spraying wilh glyphosate in late summer (February) and autumn (March) in a third experiment in 1991. All plots were rotationally grazed by cows. On average for late winter-early spring 1989 and 1990, direct-drilled and undersown plots accumulated 39 and 19'1& more dry matter, respectively, than did existing pasture (2.5 t DM/ ha), and addition of nitrogen· fertiliser increased overall herbage production by 12%, Comparable accumulations over the duration of the trials were 10, 1S and 12%, respectively. Argentine stem weevil populations had !heir greatest effect in the summer after establishment. February planting of Concord increased herbage accumulation in autumn/early winter by 2 t DM/ha compared with March planting.