HOW SOILS ARE MADE AND MIXED 5 



Ask the owner or your father which field can be plowed 

 sooner after a rain. Can you tell him why ? If a stream 

 flows through a soil containing considerable sand, the 

 soil near the water is sandier than that farther away. 

 Why is this true ? 



4. Two Sources of Soil Material. — The soils which 

 we have been studying are made up of a great deal more 

 than just pulverized rock. Some of the soils, especially 

 if they came from a field which last year was a pasture or 

 meadow, or from a fence row, or from the woods, were dark 

 in color, crumbled easily in our hands, and had that good, 

 rich " earth " smell. Along the fence row, the weeds and 

 grass have grown up, ripened, died down and decayed 

 year after year. The soil here must contain a great deal 

 of partly decayed plants, which is called humus. This 

 makes soil fertile. 



EXERCISE 3 



Object. — To find out how much of the soil comes from 

 the rocks and how much from the plants. 



Procedure. — Secure a small can full of soil from under an 

 old fence or from a field which was in pasture or meadow 

 last year ; also another can from a hillside field that has 

 been plowed for a mmiber of years, or from the middle 

 of a well traveled road. Examine each carefully, and 

 tell all you can about the color and the way each crumbles 

 in your hand. Make a mud ball the size of a large marble 

 out of each soil and let them dry for ten days. Then try 

 to break each one with your fingers or a stick. 



Now place five ounces of one of the soils as it came 

 from the field or fence row in an iron pan or old shovel, 

 and heat it red hot for at least an hour. Do you see 

 any change in color? As soon as the soil is cool, examine 

 it to see if it crumbles as easily as it did before. Heat 



