EXERCISE 4 

 A FIELD LESSON IN SOILS 



Object. To study the formation of soils and the effect 

 of location and cultivation upon their depth and value. 



Explanation. A soil can usually be separated into three 

 distinct layers : first, the surface soil ; second, the subsur- 

 face; and third, the subsoil. The surface soil is the top 

 soil and varies in depth with location and manner of forma- 

 tion. It is distinguished from the subsurface soil by color, 

 the subsurface soil being lighter in color. The subsoil lies 

 immediately below the subsurface soil and is also distin- 

 guished from the subsurface soil by having a lighter color. 

 The subsurface soil is intermediate between the soil and 

 subsoil in both location and color. 



The different layers of the soil differ in texture, that is, in 

 the size of the soil particles. Usually the surface soil has a 

 slightly coarser texture than the subsurface or subsoil. 



Equipment. 1. A soil auger. 



2. A piece of oilcloth eighteen inches square. 



Directions. Go to a near-by field in which there is a hill. 

 Examine the soil on the level land at the top of the hill, 

 on a steep slope, and in the valley at the bottom of the slope. 

 Make an examination of the soil in each place as follows : 



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