High decrease in nitrate leaching by lower N input without reducing greenhouse tomato yield

Nitrate pollution due to excessive N fertirrigation in greenhouse tomato production is a persisting environmental concern in the Mediterranean region. Driven by productivity rather than sustainability, growers continue to use very high N concentrations of more than 11 mM in greenhouse tomato production. A greenhouse study was conducted in Barcelona, Spain, over two growing seasons to analyze the effect of N concentrations from 5 mM to 11 mM (control) on tomato yield and physical quality. The relative environmental impact was calculated by using the life cycle assessment method (LCA). Our results show that N concentration in the nutrient solution can be reduced from 11 mM (control) to 7 mM under a daily mean drainage volume of 30%. This finding implies a 70% decrease in nitrate leaching without reducing tomato yield or quality. According to life cycle assessment, a reduction of 36% in N fertilizers leads to a 60% decrease in the potential impact of eutrophication, 50% decrease in the potential impact of climate change, and 45% decrease in the potential impact of photochemical oxidants.