TACTICAL APPLICATION OF FERTILIZER NITROGEN TO OFFSET A SEASONAL FEED SHORTAGE ON A HEAVILY STOCKED SHEEP FARM IN SOUTHERN HAWKE'S BAY

Abstract

An experiment was conducted within the confines of a practical farming situation. Two treatments were compared: "Control", where the normal stocking rate was imposed without fertilizer nitrogen, and "Nitrogen", where a single dressing of urea was combined with a 10% increase in the normal stocking rate. Urea was applied when ewes were set-stocked for lambing, in late winter 1970. Pasture production and animal liveweights were recorded over the ensuing three to four months. Measurements under cage exclosures in the grazed paddocks indicated an overall yield response of 1 820 kg DM/ha (+36%) to the single dressing of 58 kg N/ha. A greater response was recorded from grasses other than ryegrass, than from ryegrass, which constituted 50% of control yield. The N effect declined with time. Responses occurred irrespective of aspect or slope. Similar measurements under cages, where herbage was repeatedly cut and discarded, indicated a smaller response and failed to show residual effects of N. Ewe liveweights showed a greater increase in the Nitrogen group, and lamb liveweights were almost identical between treatments. These results indicate that urea application stimulated pasture growth sufftciently to more than meet the requirements of the additional stock