Environmental trade-offs associated with intensification methods in a pasture-based dairy system using prospective attributional Life Cycle Assessment

Abstract

The predicted increase in global demand for dairy products over the next decade is driving the global dairy sector to increase its production capacity. For the New Zealand dairy sector, farm intensification is a common strategy to increase milk production per hectare, and is generally achieved through increased stocking rate, predominately supported by different feed provision methods. In the present study, seven prospective intensification scenarios were established, and multiple environmental impacts of these scenarios were assessed using prospective attributional Life Cycle Assessment. Increased productivity per animal and increased pasture utilization efficiency reduced all environmental indicator results compared with a business-as-usual scenario (per kg of standardized milk). Increased use of locally produced maize silage reduced all environmental indicator results except for Ozone Depletion Potential, Photochemical Ozone Creation Potential, and Ecotoxicity for Aquatic Freshwater. On the other hand, the use of imported wheat grain increased all environmental indicator results except for Climate Change and Terrestrial Eutrophication Potential, and this was mainly due to the production and long-distance transport of wheat grain. Use of extra nitrogen fertilizer to increase on-farm pasture production increased five, and reduced six, environmental indicator results. In conclusion, increased animal productivity and increased pasture utilization efficiency are the most promising intensification scenarios for future New Zealand dairy systems from an environmental sustainability perspective. Scenario-based prospective attributional Life Cycle Assessment assists in highlighting the environmental trade-offs and hotspots among prospective farm intensification scenarios in pasture-based dairy systems.