The water footprint and virtual water exports of Spanish tomatoes

D. CHICO et al. 35Balance of the Spanish Ministry of the Environment andRural and Marine Affairs, which presents rather high valuesfor excess Nitrogen (MARM, 2008), 112 kgN/ha as a nationalaverage. In the case of Chapagain and Orr, they consideredthe leaching Nitrogen to be 25kg/ha from open and15 kg/ha from covered systems following Mema et al. (2005).As for the study of Aldaya et al. used an estimated leachingof 10 % of the estimated applied rate of 110 kg/ha fromFertistat database (FAO, 2010).The main producing provinces (Badajoz, Almería and ina lesser extent Murcia, Las Palmas, Granada, Sevilla,Cáceres and Navarra) are among the most effective in termsof l/kg, having achieved large yields and productivitiesthanks to intensification (García, 2009; Suárez, 2002). However,due to their huge cumulative total productions theirwater footprints are also significantly higher than the rest.This shows the pressure on the water resources in theseprovinces. For instance, in Almeria most of the aquifers inthe province are at risk of non-compliance with the objectivesby the EU Water Framework Directive (AndalusianWater Agency, 2010), so are in Badajoz the groundwaterbodies and the Guadiana river itself (CHG, 2009). As expectedfor a horticultural crop, the green water footprint isalmost negligible, both for rainfed and for irrigated openairproduction. An interesting analysis would be the studyof the social revenues of this pressure.As explained above, one of the reasons for the differentwater footprint results from other studies may be relatedto the different data used and assumptions taken to modelthe crop water use. A change in, for example, the length ofthe growing period may notably vary the crop water useand thereafter the green and blue water footprint obtained.Despite this, the values obtained here were in the samescale as those from other authors for the green and blue