Turning deficit irrigation into profit Deficit irrigation (DI) is a watering strategy where irrigation is applied only during drought-sensitive stages of a crop's growth. An EU-funded project has researched the application of DI in the Mediterranean basin. Climate Change and Environment © Thinkstock Correct application of DI requires a thorough understanding of the crop yield response to water and of the economic impact of reductions in harvest. In regions where water supply is restricted, it is sometimes more profitable for the farmer to optimise crop water productivity rather than harvest yield per unit of land. A multi-disciplinary consortium with the project 'Deficit irrigation for Mediterranean agricultural systems' (DIMAS) aimed to evaluate the concept of DI to reduce irrigation water use while maintaining farmers' profits. DIMAS researchers successfully validated a simulation model based on field data from trials under varying water stress for the main irrigated crops in the Mediterranean basin. These included wheat, sunflower, cotton, olive, pistachio and citrus. The model was based on guidelines from the United Nations' Food and Agricultural Organisation. The DIMAS project also developed a comprehensive set of DI practices and recommendations to guarantee sustainability of the methods when applied. Physical, socioeconomic and cultural factors were also taken into consideration. Merging the simulation with economic optimisation models, DIMAS produced conditions for DI applications in specific areas. Following dissemination to various agricultural systems, feedback is expected through farmers' associations and irrigation water agencies. results from this extensive study are anticipated to result in more rational exploitation of available water resources. This improvement will no doubt be accompanied by a reduction in environmental problems. Sustainable development in the Mediterranean agricultural sector will be promoted by an increase in DI applicability.
