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Abstract 67 SUMMARY The study covered 883 feddans (Pumping Station 39). Which is a part of EI-Tahadi Sector EI-Tahrir Province (150 km north of Cairo). results showed the followings: Available soil moisture was 11.03 to 17.17 lv/V). Time of surface ponding with irrigation water to raise soil moisture from wilting point ”WP” to tiled capacity ”FC” (within 60 cm depth) was 4 to 16 minutes. The basic intake rate ranged from 7.5 to 16.0 cm h-L • The ratio of ~conductive pores: storage pores~ .• I \ v . \ ,of’, ”:,.-,e S~V”\I:.” (CP:SP) 9f soil> ranged from 1.06 to 1.63 m. There was a negative correlation between tCP:SP} and the time of soil ponding to raise Boil moisture trom ~’WP~ to ”FC..•t.o• the depth of 60 em. There were variations in the requirements. time and frequency of irrigation between farms. Water loss durng irrigation. distribution uniformity. and coefficient of uniformity leU, were calculated in farms representing the area of study. Irrigation water loss by evaporation and drift ranged from 2.73 to 34.03% depending on the time of the year and the hour of day. ~--_ .. _-- --- 68 By stopping irrigation for two hours between 12.000n and 3 am. losses did not exceed 12%. There was a positive correlation between (wind speed x air temperature) and water loss. The pressure ranged between 1.32 and 2.06 atm. and sprinkler discharge ranged between 2.00 and 3.38 D13 h-~. The mean maximum sprinkler spacing calculated in the light of conditions of the system (i.e. the theoritical) was between 6.00 and 13.00 meters. Thus. the operating pressure should be improved and the spacings between lines should be 6 or 12 m depending on the wind speed and direction. Coefficient of uniformity (CU) ranged between 56.00 and 78.13%”: It could be increased to 88% by lateral offsetting and to 90% by following an irrigation rotation. Irrigation rotation could be practically achieved by manipulating power supply (electric current) among pumping stations . |