24 EG r/' T/AX A GRTCUL TURE. 



from the different conditions, as velocity of the current 

 and distance from the river, under which the silt has been 

 deposited. The soils in the northern part of the delta and 

 all other low lying lands in Egypt are liable to become 

 impregnated with common salt sodium chloride if not 

 carefully drained so as to keep the salt down to a level where 

 it will be harmless to vegetation. The presence of this 

 salt modifies the character of the soil in which it is found, 

 and is an important consideration for cultivators in 

 northern Egypt. Saltless soil is only got where the land 

 is so high that the salts have been washed away in the 

 drainage water. Irrigation, with drainage, keeps away the 

 i^alt from the surface soil. Without cultivation and irri- 

 gation, the salt rises to the surface by capillarity. Wind 

 blown sand also contributes to giving the soil a variable 

 character. 



Compared with soils formed from the rocks on which 

 they lie, alluvial soils are usually very uniform in grain. 

 The river is unable to carry stones and gravel into Egypt 

 and the soil has consequently little or no soil skeleton. 

 The large particles of a soil facilitate cultivation and 

 drainage, and the want of this soil skeleton is severely felt 

 in Egypt. The finer particles, having a larger proportion 

 of surface, are easily weathered to produce plant food, and 

 the spaces between the particles are filled with water, air, 

 or living organisms. 



To show the resemblance between the composition of 

 Nile mud and Egyptian soils, the following analyses are 

 given : 



