Complementarity in mid-point impacts for water use in life cycle assessment applied to cropland and cattle production in Southern Amazonia

Abstract

Southern Amazonia has been the center of a large expansion of cropland and cattle production through land use change in both Amazon and Cerrado biomes. While this expansion has had noted impacts on the regional water cycle, little information is currently apparent in life cycle impact assessments of both cropland and cattle products. This study applies existing models to quantify the mid-point impacts of water consumption and land occupation of cropland and cattle following distinct production systems that rely on agricultural extensification and intensification (cropland irrigation, and increased pasture productivity). We focus on both terrestrial and aquatic flows to highlight complementarity in current impact assessment models, expressed through the following impact categories: Water Scarcity Footprint, Terrestrial Green Water Flows, Precipitation Reduction Potential, River Blue Water Production, Groundwater Recharge Potential, and Runoff Reduction Potential (introduced here). Results show conditional changes in magnitude and sign of potential impacts when comparing rain-fed to irrigated cropland, particularly in the Cerrado biome. Cropland irrigation can increase atmospheric and terrestrial water flows as expressed through Precipitation Reduction Potential (−95 m3 ha−1), River Blue Water Production (299 m3 ha−1), or Groundwater Recharge Potential (215 m3 ha−1). Moreover, increased pasture productivity led to an overall decrease in mid-point impacts of cattle production on the water cycle. While this study provides additional insight into the effects of cropland and cattle production systems in Southern Amazonia, our results also highlight the complementarity of existing mid-point impacts towards a better representation of freshwater use in life cycle assessment.