Water irrigation and reducing mineral nitrogen fertilizer are critical factors to regional development. The objectives was to study the effect of water tension treatments, mineral of nitrogen and organic fertilizers combinations and their interactions on yield and its components of potato. Each irrigation treatments were conducted in a separate experiment. Every separate experiment laid-out in randomized complete block design with four replicates then combined analysis was done between irrigation treatments. Irrigation at 26cb i.e. 54.1% moisture from field capacity produced maximum values of all studied traits, except unmarketable tuber yield, tuber less than 30 mm and water use efficiency, which resulted from irrigation at 34cb i.e. 45.8% moisture from field capacity. Application of 60% inorganic nitrogen (238 kg/ha)+40% organic chicken manure (158 kg N/ha) resulted in highest values of number of tubers/plant, total tuber yield/ha, marketable tuber yield/ha, tuber grades 30-60 mm (%), tuber grades more than 60 mm (%) and WUE (kg/m 3). The interaction between both studied factors had a significant effect on all studied character, with exception un-marketable tuber yield, tuber grades less than 30 mm and more than 60 mm (%). Highest WUE were obtained as a result of irrigation at 34cb i.e. 45.8% moisture from field capacity and using 100% N inorganic and or 60% inorganic nitrogen (238 kg N/ha)+40% organic chicken manure (158 kg N/ha). It could be concluded that highest averages of WUE was recorded with irrigation at 34cb and application of 100% inorganic fertilization and /or irrigation at 34cb and application of 60% inorganic nitrogen+40% organic chicken manure.
