Irrigation Scheduling of Potato to Increase the Water Productivity under Drip Irrigation System on Sandy Soil

The use of irrigation scheduling in modern irrigation systems are a vital role to improve water productivity in arid regions. In Egypt, annually total cultivated area of potatoes on average 160 thousand feddan and this area is estimated at about 15% of the total allocated space for growing vegetables. Surface (SDI) and subsurface drip (SSDI) irrigation are highly efficient, but is not usually used properly. The object of this experiment is to to enhance yield and to save water on potato crop under irrigation methods. Results show that the water requirements was 1993.66 m3/fed. in summer season compared with 1838.18 in Nili season after taking into account the proportion of crop coefficient, with irrigation efficiency was 90% and the rate of leaching were 10% .While  the total water applied crop growth period were 1810, 1971, 1713 and 1892 m3/fed./season in the Nili season at T11, T12, T21 and T22 respectively, compared with traditional irrigation was 2750 m3/fed./season, while in the Summer season were 2050, 2243, 1900 and 2155 m3/fed./season at T11, T12, T21 and T22 respectively, compared with traditional irrigation was 2920 m3/fed./season. The water storage (water consumed) were 715.8 and 730.4 m3/fed./season in the Nili season at T11(SDI), T21(SSDI)respectively, while its values were 814.8 and 769.2 m3/fed./season in the Summery season at T11(SDI), T21(SSDI)respectively. The storage efficiency were 79.7 and 74.7% in the Nili season at T11(SDI), T21(SSDI)respectively, while it's were 83.1 and 78.2 % in the Summer season at T11(SDI), T21(SSDI)respectively. The irrigation water productivity ranges from 4.9 to 7.1 kg/m3 in Nili seasons and 5 to 7.1 in Summery seasons. The irrigation water productivity were 7.0 and 7.1 kg/m3 under T21 in Nili and Summery seasons respectively using subsurface drip. However it's were 6.5 and 6.1 kg/m3 under T21 in Nili and Summery seasons respectively using surface drip, compared with traditional irrigation treatment (T00) was 4.9 and 5 kg/m3 in Nili and Summery seasons respectively. The results were for water saving 34.2, 28.3, 37.7, 31.2% at the Nili season and 29.8, 23.2, 34.9, 26.2%, in Summery season under treatments T11, T12, T21 and T22 respectively.