Nitrogen fertiliser use in early lambing systems

Abstract

Nitrogen fertiliser was applied in June 1990 to early-August lambing systems and production was compared with traditional September lambing. Nitrogen (30 kg N/ha) increased pasture growth rates by 3-4 kg DM/ha/day and increased production by 210 kg DM/ha during July-September inclusive, Nitrogen responses were greatest in southfacing paddocks; least on easy contoured paddocks; and did not differ between "resident" pastures and "improved" pastures that had been oversown with new pasture cultivars 5 years before. Compared with traditional September lambing, early-August lambing (plus N) resulted in20% fewer lambs at weaning; 2.4 kg heavier lamb weaning weights; similar ewe weaning weights; and similar bull live weights in January. While N applications to earlier lambing systems reduced the differences in ewe and bull weights previously recorded between the lambing date treatments, it was not a profitable strategy. Assessment of pasture response to N (30 kg N/ha) was repeated in 1991. Nitrogen increased production by 260 kg DM/ha and responses were similar for all paddock and pasture types. Keywords nitrogen fertiliser, early lambing, hill country