To reduce the environmental burden of agriculture, suitable methods to comprehend and assess the impact on natural resources are needed. One of the methods considered is the life cycle assessment (LCA) method, which was used to assess the environmental impacts of 18 grassland farms in three different farming intensities - intensive, extensified, and organic - in the Allgau region in southern Germany. Extensified and organic compared with intensive farms could reduce negative effects in the abiotic impact categories of energy use, global warming potential (GWP) and ground water mainly by renouncing mineral nitrogen fertilizer. Energy consumption of intensive farms was 19.1 GJ ha(-1) and 2.7 GJ t(-1) milk, of extensified and organic farms 8.7 and 5.9 GJ ha(-1) along with 1.3 and 1.2 GJ t(-1) milk, respectively Global warming potential was 9.4, 7.0 and 6.3 CO2-equivalents ha(-1) and 1.3, 1.0 and 1.3 CO2-equivalents t(-1) milk for the intensive, extensified and organic farms, respectively. Acidification calculated in SO2-equivalents was high, but the extensified (119 kg SO2 ha(-1)) and the organic farms (107 kg SO2 ha(-1)) emit a lower amount compared with the intensive farms (136 kg SO2 ha(-1)). Eutrophication potential computed in PO4-equivalents was higher for intensive (54.2 kg PO4 ha(-1)) compared with extensified (31.2 kg PO4 ha(-1)) and organic farms (13.5 kg PO4 ha(-1)). Farmgate balances for N (80.1, 31.4 and 31.1 kg ha(-1)) and P (5.3, 4.5 and -2.3 kg ha(-1)) for intensive, extensified and organic farms, respectively, indicate the different impacts on ground and surface water quality. Analysing the impact categories biodiversity, landscape image and animal husbandry, organic farms had clear advantages in the indicators number of grassland species, grazing cattle, layout of farmstead and herd management, but indices in these categories showed a wide range and are partly independent of the farming system. (C) 2001 Elsevier Science B.V. All rights reserved.
