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The actual transpiration of corn (Zea mays L.) was determined by hydraulic lysimeters, by the inflow-outflow method and by use of a neutrone probe. Two irrigation treatments were used; wet and dry. Under the wet treatment, 740, 858, and 743 mm of irrigation water was used during the seasons 1968, 1969, and 1970 respectively. Under the dry treatment, amount of irrigation water used was 560, 627, and 565 mm during the seasons 1968, 1969 and 1970, respectively. Ratios of actual transpiration (Et) to Penman's estimate of potential evaporation (Eo), evaporation from a Class-B pan (EpB), global radiation (Rg) and net radiation (Rn) were calculated. Values of Et measured by the different methods are in good agreement. Seasonal averages of Et , were 6-2 and 4-9 mm/day under wet and dry treatments, respectively. The Et/Eo, Et/EpB, Et/Rg and Et/Rn ratios increased with leaf area index (L.A.I.) and reached their maximum values when L.A.I, reached its maximum value of 1-03 under wet and 0-92 under dry treatment. The empirical coefficient (/ = Et/Eo) under wet treatments was found to be higher than that given by Penman for short grasses and about the same as that obtained by Boumans et al. (1963) for golden-gram (Phaseolus aureus) in Iraq for the months August and September. The empirical coefficient Kb in the BlaneyCriddle formula was greater than the value given by Blaney and Criddle for an arid climate, and less than the value obtained by Boumans et al. for golden-gram in Iraq. It was further found that water use efficiency for grain production was greater under dry than under wet treatments.

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A saline soil from Euphrates alluvium at Abu-Ghraib was leached in two lysimeters with river water and the changes in composition of the soils and of the leachates were measured as well as the hydraulic conductivity. The results show that the presence of gypsum prevents the soils becoming sodic as leaching with irrigation water of favourable composition proceeds.

The actual transpiration of Mexipak wheat (Triticum aestivium L.) was determined by the inflow-outflow method and by soil moisture determination by the use of a neutron probe and gravimetrically. Three irrigation treatments were used during the 1969 season, wet, medium and dry. Amounts of water given were 370, 310 and 255 mm for wet, medium and dry treatments respectively. One irrigation treatment was used during the 1971 and 1972 seasons in which 620 and 700 mm of water respectively was given. However, during the 1973 season, two wet irrigation treatments of 560 and 670 mm of water were used. Values of Et measured by different methods were closely related. Seasonal averages of Et were 2-55, 1-99 and 1-62 mm/day for wet, medium and dry treatments respectively. The empirical coefficient (/ = EtjEo) under wet treatment, was found to be higher than that given by Penman (1956) for short grasses and higher than that obtained by Boumans et al. (1963) for wheat and barley in Iraq. The empirical coefficient Kb in the Blaney-Criddle formula was less than the value given by Blaney & Criddle (1950) for an arid climate and less than the value obtained by Boumans et al. (1963) for wheat in Iraq. The water use efficiency for grain production was greater under dry than under wet treatment.

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