Abstract

Four 6.4 ha farmlets each stocked with 24 high genetic merit Friesian cows were used to determine the effect of nitrogen fertiliser (N), and a long summer grazing rotation on pasture and milk production in summer. Treatments were 0 )-N) or 50 kg N/ha (+N) in December, January and March and a 16 day (16) or 40 day (40) rotation. Treatments started 15 December, following a two week uniformity period, and ran until 29 April. On the 16 and 40 day rotations N increased net herbage accumulation by 0.8 t DM/ha, and milksolids (MS) production by 92 and 38 kg/ha respectively. Across both nitrogen treatments, the 40 day rotation increased net herbage accumulation by 1.7 t DM/ha. The MS production was 39kg/ha greater on the -N40 than the -N16 treatment whereas that of the +N16 and +N40 did not differ significantly. The N and long rotation treatments also resulted in higher average herbage mass and cow condition at the end of the experimental period. It is concluded that N in early summer and a long summer rotation are useful management practices to reduce the effects of summer dry periods.

TB, McFadden, GA Verkerk, BA Clark, RC Hovey, and KL Macmillan

Proceedings of the New Zealand Society of Animal Production, Volume 55, , 21-22, 1995