IRRIGATION AX.D DRAINAGE. lf>7 



unclose a considerable area of land liable to become water- 

 logged. A small infiltration drain alongside a large high 

 level canal would in many cases save adjacent land from 

 deterioration caused by waterlogging. The system of 

 making a central drain between two canals is meant to 

 cure the evil of waterlogging. Infiltration drains alongside 

 the canals would prevent the evil. 



All large irrigation and drainage works in Egypt, are 

 undertaken by the Irrigation Department of the Ministry 

 of Public Works, and it is therefore only necessary to 

 consider such minor works as mav fall to the agriculturist 

 to execute for himself. He will rarely have to deal with 

 larger blocks of land than those containing a few thousand 

 feddans. 



The quantity of water required varies according to crop, 

 soil, and time of year. Cotton in its early stage, if sown on 

 soil retentive of moisture, and which has been well watered, 

 may go 40 or even 50 days without a watering, but on other 

 land, salty or readily parting with moisture, it would not 

 go half the time. In later stages of growth the weather 

 is hotter and the greater leaf development causes greater 

 exhalation of moisture so that irrigations are necessarily 

 more frequent. Berseem in winter requires only one 

 watering after each cutting, once in 40 days. When hot 

 k ham seen winds occur in April, berseem would be forced 

 into flower and dried but for an extra irrigation. Cereals 

 require about two waterings during the period of their 

 growth which is in winter. Whilst then different crops, 

 and the same crop at different stages of development, vary 

 greatly in demands for irrigation, still the duty of water can 

 be calculated when a sufficiently large area is considered. 



J o 



For summer crops in Ipper Egypt the calculation for 



