LEGUME AND FERTILIZER NITROGEN IN NEW ZEALAND PASTORAL FARMING

Abstract

The role of clovers in grass/clover pastures is discussed. Their nitrogen-fixing capacity and direct contribution to yield are greatly modified by climate, nutrient supplies and soil nitrogen availability. A ceiling to production from grass/clover pastures is envisaged where the application of fertilizer nitrogen will be required for further increases in productivity using present species. Satisfactory short-term pasture responses to nitrogen have been measured. Modification of these by climatic, pastoral and managerial factors is discussed. The long-term implications of nitrogen usage on pastures are not clear. More research is required before the place of fertilizer nitrogen for forage production in New Zealand pastoral farming can be properly assessed.