摘要：In this work several performance indicators such as the Annual Relative Irrigation Supply (ARIS) and the Irrigation Water Productivity (IWP), have been considered to evaluate the changes in the cotton irrigation management due to the decoupling of the European Union Subsidies. For this purpose, a modern irrigation scheme, the Genil–Cabra Irrigation Scheme (GCIS) located in Southern Spain, has been selected. The total irrigated area is 6,900 ha with wheat, olive and cotton as the main crops. The irrigation season 2004/05 was the period when the crop pattern and water management trend changed dramatically. From this year to the present the area cultivated with crops with high water requirements like cotton, sugar beet and maize has been reduced almost by half, while the area with low irrigation requirement crops (winter cereals, sunflower or olive) has increased of 37%. After the decoupling of the EU cotton subsidies in 2006, the cotton agricultural practices have changed toward a less intensive production system, including both, lower water application (ARIS for cotton decreased from values higher than 0.8 to 0.5 in the irrigation season 2006/07) and less agrochemical usage. In terms of sustainability, the reform has increased the cotton irrigation efficiency (IWP for cotton increased from around 0.7 €/m3 to 1.0 €/m3 in the irrigation season 2006/07) and has reduced its environmental impact.
