Using Life Cycle Assessment (LCA) to assess water use in tomato production

In response to concerns about global water scarcity and food security, water footprints have emerged as one important indicator of sustainable agriculture. In this paper the water footprints of two greenhouse tomato production systems are presented which form part of a wider study on sustainable food production using Life Cycle Assessment (LCA). The water footprints, which offer a quantitative measure of the way a production system contributes to the problem of physical water scarcity, were calculated using a recently developed LCA-based calculation method, taking into account the local water stress where production occurred. For greenhouses located in Sydney and Guyra (NSW northern tablelands), the world normalised water footprints of market tomatoes were 35 and 3 L H2Oe per kg fresh weight respectively. In comparison, the water-use efficiency of these systems was 50 L (Sydney) and 39 L (Guyra) per kg. Although water-use efficiency is popular amongst agronomists and is important for benchmarking local resource-use efficiency, it does not address the wider question of sustainable freshwater use. Water footprint on the other hand is capable of sending signals on the way the agricultural production system limits the availability of freshwater for the environment and/or other human uses. Metrics such as water footprint offer a useful and additional perspective for moving towards environmental sustainability.