Nutrient budgeting as an approach to improving nutrient management on Australian dairy farms

Dairy farming in Australia continues to intensify. Increased stocking rates have resulted in increased milk production per ha, but have also required greater inputs of purchased feed and fertiliser. The imbalance between nutrient inputs, primarily as feed and fertiliser, and nutrient outputs, in milk and livestock, has resulted in significant nutrient accumulation on dairy farms and, consequently, a greater risk of nutrient loss to the environment. Nutrient budgeting is a technique used to quantify or predict nutrient deficits or surpluses, either at a whole- farm or field scale, in an attempt to improve nutrient use efficiency and reduce nutrient losses from agriculture. A broad range of nutrient budgeting approaches are used internationally, and depending on their purpose, they vary from the very simple to the very complex. Nutrient budgeting has been widely used to assist on- farm nutrient management decisions, in research to identify major nutrient pools, transformations and losses, to enable farmers to access cost- sharing support from governments, and in some countries as a major regulatory tool. The changing nature of Australian dairy operations, the increasing societal pressure on the farming community to reduce nutrient losses to water and air, and the need to provide evidence that farm practices are meeting environmental standards, justifies the need for improved nutrient management practices on Australian dairy farms. This paper describes different types of nutrient budgeting approaches used internationally and assesses the benefits of developing a practical, scientifically rigorous and nationally standardised nutrient budgeting approach for the Australian dairy industry.