Effect of Nitrogen Fertilizer on Dairy Farm Productivity and Viability in the Subtropics

Nitrogen fertiliser as urea was applied to dryland grass pastures in south east Queensland to improve the quantity and quality of feed on offer to grazing dairy cows. Milk production per cow and reproductive performance data suggest that the groups of cows that benefited most were the winter calvers, which calved at significantly higher live weights and were therefore better able to overcome short periods of nutritional stress due to feed shortages in winter. Whole farm input• output data suggests that a reasonable whole farm production model relating milk produced from paddock feed and nitrogen fertiliser use is feasible. The impact of altering the input mix, predominantly replacing purchased grain inputs with fertiliser inputs is reported in terms of costs of production and gross margins over a S- to 6-year period.