Effect of nitrogen fertiliser on nitrogen yield from lucerne under cutting and grazing managements

Abstract

Abstract Wairau lucerne fertilised with P and K in amounts equivalent to those removed in a crop yielding 20 000 kg/ha dry herbage, and irrigated, was either cut or grazed with sheep at 5-weekly intervals. Annual yields of dry herbage were 15 940 kg/ha where cut and 19 900 kg/ha where grazed. Application of 710 kg N/ha in split dressings to a cut treatment increased the herbage yield to 18 040 kg/ha. Nitrogen yields in cut herbage were 550 kg/ha without N fertiliser and 660 kg/ha with N fertiliser. In grazed herbage they were 680 kg/ha without N fertiliser and 700 kg/ha with N fertiliser. Extracted protein yield from cut herbage was increased from 1790 to 2110 kg/ha with N fertiliser. The relevance of these results to the practices of extracting leaf protein and to feeding protein-extracted herbage to stock on the same area from which the crop had been harvested is discussed.