Influence of soil properties on irrigation management in Egypt

This report reviews water management of these soils and discusses the influence of the soil type on the design and operation of Egypt"s irrigation systems. Although considered difficult soils to manage, vertisols can be irrigated fairly efficiently with minimum management due to infiltration characteristics which allow the soil water deficit to be replaced. Uniform water applications are generally possible even with highly variable flow rates. Since available water was considerably less than expected from clay soils, irrigation had to be planned around a deficit of 5-7 cm. Problems of canal maintenance in vertisols (areas of cracking and heaving, surface drainage due to sealing) suggest that canals lower than the farmers" fields and lift irrigation are preferable to raised canals and gravity irrigation in these areas. Entisols are not suitable for surface irrigation; infiltration rates are too high, resulting in extensive conveyance losses. Distribution of water through the system is uneven and irrigation efficiency is very low, resulting in a high water table which partly compensates for this inefficiency by allowing subirrigation. Included are 16 tables and a three-page bibliography (1962-84).