Indicators of resource use and environmental impact for use in a decision aid for Danish livestock farmers

Farmers lack well documented sets of farm level indicators to allow their own evaluation of environmental impact and to stimulate the development of more environment friendly farming practices. A set of farm level indicators of resource use and environmental impact on livestock farms was developed as part of a decision aid for farmers. The indicators were meant to be part of an extended farm account and included the surpluses and efficiencies of N, P and Cu, the energy use per kg grain and per kg milk or meat, pesticide treatment index (TFI), % unsprayed area, % small biotopes on the farm, and % weeds in grain crops. The indicators were tested on 20 Danish dairy and pig farms over a period of 3 years in order to see if they were suitable for use in the farmer's management. The third year, farm gate surpluses varied between 89 and 265 kg N ha(-1), 2 and 31 kg P ha(-1) and 0.1 and 0.8 kg Cu ha(-1). Energy use varied between 2.1 and 4.1 MJ kg(-1) milk and between 14 and 20 MJ kg(-1) live weight pig sold. For all indicators, except energy use per kg grain, the variation in indicator levels between farms was more important than the variation between years within each farm. There was significant variation between farms after correction for stocking rates and soil-and farm types, which suggests that the indicators reflect differences in management practise on comparable farms. It was demonstrated that these differences between similar farms and between the years on the individual farms might be explained by the detailed knowledge of management of the farms' different subsystems (herd and crops). The information given by the indicators is discussed from environmental and management points of view and problems of defining and interpreting the indicators are identified. Given further development of indicators for soil quality and nature values, the farm level indicators seem a promising way of enabling farmers to include environmental topics in their management. (C) 1999 Elsevier Science B.V. All rights reserved.