Soil nutrient concentrations and farm gate nutrient balances for dairy farm management in Tasmania

Soil testing was undertaken on 1698 pasture paddocks on 109 dairy farms across Tasmania as part of the Fert$mart planning process. Forty-five per cent of paddocks had soil Olsen P concentrations above the concentration where any response could be expected from the application of additional P fertiliser. There was uneven distribution of nutrient concentrations across farms possibly relating to different soil types, previous fertiliser applications and grazing management practices. The range in Olsen P across paddocks was 5–134 mg/kg. Many paddocks (43%) had mean soil extractable K and KCl-S (39%) concentrations above that required for optimum plant growth. Only 3.7% of paddocks tested had nutrient levels in the optimum range for all of the four nutrient measures. Whole farm nutrient budgets found deficits to large surpluses for P, K and S. The Fert$mart process combines a farm nutrient budget with soil testing as tools for improved fertiliser management.