Egypt faces a very challenging situation regarding decreasing water availability and the area of arable land specified for crop production. Uneven water distribution, misuse of water resources and inefficient irrigation techniques are some of the major factors playing havoc with water security in the country, so maximizing water productivity is one of the most important strategies. Therefore, the aim of this study was to investigate the drip irrigation management for sunflower grown under clay soil conditions to encourage farmers to use drip irrigation systems in their clay soil fields. Such management should be a tool for maximizing crop yield, increasing water productivity (Water Use Efficiency, WUE) and saving water to irrigate new areas. A field experiment was conducted to study the effect of deficit irrigation and drip irrigation laterals arrangements on yield and water productivity of sunflower crop (seed and oil). Deficit irrigation treatments were (FI100), (DI80), (DI60) and (DI100-60) (Full crop evapotranspiration 100% ETc, 80% ETc, 60%ETc and (100 – 60 % ETc respectively). The DI100-60 treatment was applied as 100 % ETc up to seed formation then reduced to 60%ETc before crop harvesting. ) The drip irrigation lateral arrangements were (R1L1-2) and (R2L1-4) (single and double planting rows per one drip irrigation lateral line, with 2 l/h and 4 l/h drippers, respectively), this was to ensure similar water application rate per row for both lateral arrangements. Results revealed that using higher dripper discharge (4l/h) under clay soil conditions resulted in wide horizontal distribution of moisture patterns more than the vertical distribution. Salt accumulation slightly increased with deficit irrigation. Applying deficit irrigation by either DI80 or DI100-60 produced almost the same or more yield of sunflower seeds and oil than that obtained from full irrigation FI100, besides saving about 20% of irrigation water. These two deficit irrigation treatments maximized water productivity WUE. The highest seed yields were 1895 kg/fed and 1822 kg/fed obtained from R1L1-2 and R2L1-4 under DI100-60 respectively. The oil yield values were taken the same trend as seed yield. Accordingly, it could be recommended that irrigating row crops such as sunflower under clay soil conditions could be done by using one lateral line of 4l/h drippers per two planting rows and applying DI80 or DI100-60 deficit irrigation strategy, taking many advantages such as increasing seed and
oil yield, maximizing WUE, reducing the cost of drip lateral lines by 50% and saving water by about 20%).