The water footprint and virtual water exports of Spanish tomatoes

34 THE WATER FOOTPRINT OF TOMATO PRODUCTIONthe European Union, being the UK, Germany and the Netherlandsthe main importers (MITYC, 2009). As an average, 93%of the virtual water exports correspond to the EU.The average water apparent productivity of the exportedproduction in the period was 8.8 €/m 3 . This productivity ishigher than the average WAP of 5 €/m 3 , and closer to 7.1€/m 3 of greenhouse production and to 7.2 €/m 3 correspondingto production using groundwater. These results are actuallyclosely related, since the main exporting provinces, Almería,Murcia and Las Palmas, have a production mainly undergreenhouses conditions, using groundwater and in early andlate season (MARM, 2010b; Suárez, 2002 García, 2009). Togetherthey represent more than 60% of the annual exports(MICYT, 2009).5. DISCUSSIONThis study provides a detailed analysis of the green, blueand grey water footprint of tomato production in Spain, bothin l/kg and hm 3 , for all the Spanish provinces during theperiod 1997-2008.The results obtained for the average green and blue waterfootprint in terms of l/kg were in the range of those fromother studies, whereas the values obtained for the averagegrey water footprint were much higher. For tomato productionin Spain, Chapagain and Orr (2009) obtained values ofabout 14, 60 and 7 l/kg for the green, blue and grey waterfootprint respectively. In their study of the water footprintof tomato production in Italy, Aldaya et al. (2010) calculatedvalues of 35, 60 and 19 l/kg for green, blue and grey waterfootprint respectively. These differences with the study ofChapagain and Orr may be related to the different datasources and assumptions made. We followed the Nitrogen