ABSTRACTTo meet the demand for agricultural commodities, the world’s irrigated area needs to be increased by 15% and 60 % of it needs to be modernized. The expansion and modernization of irrigation in the world is primarily achieved using pressurized irrigation systems. These systems ease control of irrigation water and fertilizers, but pose three specific challenges to Spanish society:1) To moderate energy consumption, which in combination with escalating energy costs are affecting the economic viability of many modernized irrigated areas and limiting the development of new areas;2) To optimize the large variability of irrigation scheduling practices which have been developed by farmers;3) To assess the present and future impact of irrigation modernization on diffuse agricultural pollution, and on how indicators are used to support the implementation of environmental policies.The project will develop research and development activities over four years to address the three specific challenges with direct support from stakeholders.We will analyse technical alternatives to the optimization of energy consumption by lowering nozzle pressure in solid-set sprinkler fields and pivots. Technical and agronomic traits of sprinklers designed to operate at low pressures will be analysed. Simulation analyses and experimental efforts (two crop cycles) will permit to establish the technical, economic and productive possibilities of operating solid-sets and pivots at low pressure. The effect of low-pressure irrigation will be assessed at the plot and collective network scales. Irrigation management alternatives will we experimentally evaluated for a maize crop. Alternatives will be based on irrigation frequency and timing (day/night operation).Agronomic experiments will illustrate the effect of sprinkler irrigation management variables on microclimate, plant growth and development, foliar ion uptake, soil water regime, photosynthesis and maize yield. Management guidelines will be developed maximizing water and crop productivity.Finally, we will implement scientific and technological developments to improve the accuracy of water balance in experimental sprinkler-irrigated watersheds. Developments include the estimation of actual evapotranspiration from satellite remote sensing, the estimation of crop coefficients from thermal integrals and monitoring water table fluctuations to improve groundwater flow quantification. The accuracy of agricultural diffuse pollution indicators directly relies on the quality of these water balances. Indicators will be applied to environmental impact assessment in sprinkler irrigated areas of the Ebro valley. The analysis will also apply simulation models to develop strategies for diffuse pollution control at the plot and watershed levels. The DSSAT and SWAT models will be applied to assess future scenarios based on changes in the use of production inputs, water scarcity and climate change. Following the completion of project activities, technical and policy innovations will be developed to overcome the current challenges.