58 PRODUCTIVE FARMING 



Exercise. — To Show Kinds of Soil and Subsoil. — Have 

 pupils bring to school in small boxes or tin cans samples of 

 different kinds of soil and subsoil of the neighborhood 

 (Fig. 33). The pupils should classify and name these. 

 Much benefit may come by discussing the relative value 

 of these types of soil and subsoil. 



REVIEW. 



1. Name as many different kinds of soil as you can. 



2. How many of these have you seen? Where? 



^. What kind of rock forms sand when crumbled ? 



4. In what ways is clay soil better than sandy soil ? 



5. In what ways is sandy soil better than clay soil ? 



6. Name several ways in which lime or limy substances are help- 

 ful to soil. 



7. What is humus? 



8. How does humus improve sandy soil? How does it improve 

 clay soil ? 



9. Describe a good farm soil. 



10. How may the subsoil differ from the surface soil ? 



References. — Physical Geographies will be helpful in the further 

 study of the topics taken up in the chapters on Soils. Let the most 

 advanced pupils in the class read the chapters on soil movement in a 

 good Physical Geography and report to the class. 



CHAPTER VI. 

 SOIL MOISTURE, 



Water in Soils. — Many soils contain too much or too 

 little water. The water in soils may be in three conditions: 

 (a) Free water, or that which would flow into a hole dug for 

 a post or telephone pole. (6) Capillary water, or that which 

 tends to fill the small spaces between fine particles of soil, 

 as the oil of a lamp fills the spaces in the wick above the free 

 oil in the lamp. This is called also coarse film or simply film 

 moisture, (c) Fine film water, or that which clings to the 

 surface of each small bit of soil even when it is as dry as road 

 dust. This is called also hygroscopic moisture,. If too much 



