Nutrient budgets as a tool for researchers and farmers.

Whole-farm budgets for N, P and K have been determined for the organic dairy farm at Trawsgoed in mid-Wales and used to assess the potential value of budgets as a management tool for optimising nutrient use. Most of the information needed by farmers to calculate whole-farm budgets is available on commercial farms but an important limitation is the difficulty of estimating N fixation. Whole-farm budgets do not provide sufficient information for use in managing nutrient flows, which requires moredetailed field budgets. Information for determining budgets at the field scale is less readily available. The studies have examined the use of farm and field budgets to provide an estimate of the nutrient content of animal manures and slurries produced on the farm.