CHAPTER III. 

 THE RELATION OF SOILS TO IRRIGATION. 



ajT T was the blind poet Milton who said, " Fame is 

 i no plant that grows on mortal soil." He 

 9ISas might have added that famous plants are to 

 grow on irrigated soil. The nature, condition 

 and situation of soils compose a most important fadlor 

 in successful irrigation, and should especially be under- 

 stood by every person who essays to apply water by 

 artificial methods. In the first place, it may be well to 

 understand that primarily soil is rock disintegrated, 

 dissolved, or pulverized by the action of the air, water, 

 and ice, aided chemically by the various salts and acids 

 present in the soil, and fertilized by decayed vegeta- 

 tion, animal excretions, and chemical agents. 



Classes of Soils. — Nominally there are two dis- 

 tindt classes of soils — the sedentary and transported 

 soils, which embrace the drift and alluvial soils. 

 Specifically soils are distindtive according to their 

 physical charadleristics, and may be classified as 

 gravel, sand, clay, loam, marl, lime, salt, peat, muck, 

 or humus. Pure sand consists almost entirely of small 

 grains of silica or quartz, and is not a plant food. 

 Plants cannot use it. It is insoluble in water and in 

 acids, and has no adhesive tendency ; hence, adling as 

 a divider in the soil, it makes the land easy to work 

 and facilitates the passage of roots in search of food, and 



