Field experiments were carried out during two summer seasons of 2009 and 2010 at Shandaweel Agriculture Research Station, Sohag Governorate to investigate the effect of irrigation intervals and potassium fertilization on common bean cultivar “Nebraska" under Sohag conditions. Three irrigation intervals were used i.e., (7, 14 and 21 days). Potassium fertilizers were used as five treatments i.e., (unfertilized, Spraying potacin once, twice, three times and the recommended dose of potassium sulphate 50 kg K₂O/feddan as soil dressing). The obtained results indicated that there are significant differences among different irrigation intervals under study. The best irrigation intervals were each 14 days in most studied charactersitics. Fertilized common bean plants with recommended dose of potassiun sulphate gave the best results in all studied charactersitcs. There are little differences between  recommended dose of potassiun sulphate and spraying potacin three times (30% K₂O), consequently spraying potacin three times appears more economically to get high net return from dry seed yield. The interaction between the two studied factors significantly affected all studied characteristics. Moreover, the highest values were achieved by the interaction between irrigation intervals each 14 days with recommended dose of potassiun soil dressing in both seasons. Watering common bean plants every 14 days and spraying with potacin three times recorded the highest values of farmer net return (2812.0 LE) followed by potassium soil dressing as compared to all studied treatments. The farmer net return obtained by irrigation at 14 days and spraying with potacin three times exceeded fertilizing with recommended dose of potassium sulphate by 10.2%. This attractive finding means that it could be replaced spraying with potacin three times instead of the recommended dose of potassium sulphate to achieve the highest farmer net return and best water use efficiency over the two seasons.