NATURE AND ORIGIN OF THE SOIL. ' 31 



PART II. 



CHAPTER VIII. 



NATURE AND ORIGIN OF THE SOIL. 



All the plants grown upon the farm or in the garden grow 

 in the soil; even those that appear to be growing in streams 

 and marshes have their roots in the soil beneath the water. 

 Sometimes we see plants grown in water only in the house or 

 greenhouse, but most of those found there are grown in pots 

 filled with soil. The plants found on the surface of rocks and 

 on old rail fences are of a low, simple order. We may then 

 conclude that most of the plants that we are now familiar with 

 require soil, and we therefore shall study for a while the soil, 

 its nature, its origin, and its improvement. 



KINDS OF SOIL. Sandy soil is made up principally of sand. 

 If we take a handful of dry sand we find that it consists of 

 small hard grains that are easily mixed together. If we 

 moisten it, it will cling together and can be moulded into 

 various forms, but when it dries the particles all fall 'apart 

 into fine sand as before. Then there is clay of various colors, 

 sometimes red, sometimes almost white, sometimes nearly 

 blue. If we moisten it we can mould it, but when it dries 

 it keeps its shape and becomes hard. We readily see the 

 difference. When we walk over wet sandy soil and wet 

 clayey soil, the former, when dry, readily rubs off our boots, 

 the latter sticks. Sand is used for making moulds in the 

 foundry and clay is used for making models by the artist; the 



