The third irrigation scenario is designed to test the effects of interaction between the irrigation efficiency and irrigation expansion scenarios. In addition, there are also international spill-over effects. World prices for maize and wheat are lower by 3% and 1% respectively compared to scenarios where the improved varieties are adopted only in the United States, and by 4% and 2% respectively when adopted throughout the OECD (Figure 13). For those regions that are currently battling water stress, e.g. the Mediterranean, irrigation efficiency measures contribute to improved yields on the order of between 3% and 5% in irrigated areas growing mainly maize and vegetables.