ABSTRACT
In the design and planning of irrigation projects, most "water requirement" studies have focused on climatic factors that influence water use for maximum crop production. This chapter gives the reader an overall perspective of deficit irrigation, from the basic concepts to some of the options, challenges, and tools that could be considers and integrates during the development of a viable deficit irrigation strategy. Deficit irrigation is an optimizing strategy whereby net returns are maximized by reducing the amount of irrigation water applied to a crop to a level that results in some yield reduction caused by water stress. The options to simulate and integrate irrigation water supply and demand in the ACRU modeling system are commendable and make for a powerful irrigation planning tool. Irrigation water applications can be initiated prior to planting and together with applications early in the growing season can help to refill the potential soil water store when evapotranspiration requirements are low.
