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Abstract
According to the increase of population and limited cultivated area, it was necessary to make the crop rotation as to be permissible for more than one crop per year, there fore, the permanent irrigation system was performed. As permanent system of irrigation is always known to be connected with relatively moisture condition, the problem of field drainage was arised. Therefore, the aim of this investigation was to study the physical and chemical properties of soils and yield of some crops under application of drainage by different spacing between tiles, beside other amelioration operations such as subsoiling or/and addition of gypsum.