Abstract
In the dual irrigation technology (DIT), irrigation process is divided into two stages. In the first stage saline water is added as a part of irrigation water requirements , then good quality irrigation water is supplied in the second stage to complete irrigation water requirements. Piston flow may accurse in the soil because the time interval between two stages as short as possible , so the water content is greater than field capacity . Piston flow leaches the saline water that used in the firs stage of (DIT) under the root zone depth, so it is minimize the salinity effects of that water. Drainage water of 6 ds/m and Euphrates river water (1ds/m) are used to irrigate corn under furrow irrigation system with (DIT) at Ramady city in Iraq. Advance face in the furrow completes from drainage water , then second stage of (DIT) using river water . The experiment results summarized in the high relative yield (more than 95%) and saving about third quantity of fresh irrigation water. No significant differences in the salinity effects at the upper two thirds of the root zone depth compared with some furrows irrigated by river water only . Salinity effects at the lower third decrease as the distance from the upstream of the furrow increase, logarithmic relation between salinity effect and furrow length is proposed
Key words: Dual Irrigation , saline irrigation water , water quality
