Beyond the Water Footprint : A new framework proposal to assess freshwater environmental impact and consumption

Because the assessment of grey water according to the Water Footprint Network (WFN) permits to quantify the dilution volume to restore water quality considering the substance that demands the highest dilution volume, the effect of other polluting substances (e.g., nitrogen, phosphorous, pesticides) applied on field cannot be evaluated. Nevertheless, the environmental load of all these substances cannot be neglected, especially when huge amounts of organic fertilisers are spread.Additionally, because blue water quantification with WFN permits to analyse only the water consumed by the crop (mainly for irrigation purposes), a method assessing the gross irrigation volume effectively applied on field was used (i.e. Water Footprint Applied - WFA).A Pollution Water Indicator (PWI) was developed to denote the intensity of water pollution identifying the effect of the main polluting substances from crop cultivation. For PWI, both grey water and the water-related environmental impact categories (freshwater eutrophication, marine eutrophication and freshwater ecotoxicity) evaluated by means of Life Cycle Assessment (LCA) were considered.In this context, this study proposes a framework for assessing both the environmental impact and the consumption of freshwater. Different organic fertilisers spreading techniques with different timing of incorporation and straw management and three irrigation technologies with variable technical efficiency were compared for WFA quantification of maize grain production in Northern Italy.With regard to organic fertilisers spreading, PWI resulted better when nutrients leaching is reduced, while it was worse with fast soil incorporation and direct soil injection of organic fertilisers that, reducing ammonia volatilisation, involve higher nitrate losses. As concerns irrigation, sprinkler and drip irrigation are highly recommended because they permit to apply water volumes much close to the consumed ones, with blue water between -33% and -60% of total WFA with drip instead of surface irrigation.