Nutrient Management Approaches and Tools for Dairy farms in Australia and the USA.

Authors: GOURLEY, C - DPI-VICTORIA, AUSTRALIA; Powell, Joseph

Submitted to: Proceedings of Babcock Institute Technical Workshop
Publication Type: Review Article
Publication Acceptance Date: 12/1/2007
Publication Date: 12/30/2007
Citation: Gourley, C.P., Powell, J.M. 2007. Nutrient Management Approaches and Tools for Dairy farms in Australia and the USA. Proceedings of Babcock Institute Technical Workshop. Babcock Technical Bulletin 2007-04. Available at://babcock.cals.wisc.edu/publications/display.lasso?

Interpretive Summary: On dairy farms in Australia and the USA, nutrient imports (e.g., fertilizer and feed) often exceed exports (i.e. milk and animals). This can lead to nutrient accumulation, nutrient loss such as leaching and runoff, and environmental contamination. This publication describes and evaluates various nutrient management tools available to dairy farmers, advisors, and researchers. There is further scope to improve nutrient management tools, to not only quantify whole-farm nutrient balances, but also to identify opportunities for enhanced nutrient use within farm components.

Technical Abstract: In Australia and the USA, nutrient imports and accumulation on dairy farms can be a problem and may pose a threat to the greater environment. While the major nutrient imports onto dairy farms (i.e. fertilizer and feed) and exports (i.e. milk and animals) are generally the same for confinement-based and grazing-based dairy operations, within-farm nutrient cycling processes may be quite different. In confinement-based operations, farmers generally manage mixed dairy cattle and cropping operations, and have more control on cow diets, which in turn influences the quantity and nutrient concentration of manure, and the capture, storage and land application of excreted manure. In grazing-based dairy operations, farmers manage grazed pastures, and although they purchase feed, they generally have less control of dairy cow diets, with feed quality and nutrient content varying throughout the year. Additionally, the redistribution of manure nutrients in the landscape is largely from direct deposition by animals. Manure deposition is often uneven, with high nutrient loads in some areas which may pose a high risk of nutrient loss and environmental contamination. There are many nutrient management tools available to dairy farmers, advisors, and researchers. Generally, these tools attempt to quantify nutrient imports and exports at the farm scale, nutrient flows and use efficiencies at the component scale (i.e. feed, milk, manure, land-application, plant uptake) and soil fertility status and nutrient loss at the field or paddock scale. There is further scope to improve nutrient management tools, so that they not only quantify nutrient balances on dairy farms, but also assist in identifying opportunities for enhanced nutrient use within farm components, and reduced nutrient losses.