THE WATER IN THE SOIL 23 



Place the lower ends of the chimneys or cylinders in 

 pans of water, and watch the moisture rise in the soil. 



Conclusion. — Will it pay to disc stubble or trashy 

 fields before plowing? Why? What is an ideal condi- 

 tion of the soil for the freest rise of moisture through it? 



14. How the Farmer prevents the Escape of Film 

 Moisture. — The roots of plants often feed very near the 

 surface of the soil. These roots need the moisture that 

 comes up by capillary action. The farmer wants there- 

 fore to bring this water up to the roots, and yet not to let 

 it escape into the air. He can do this by mulching with 

 straw, but this may keep out the air, which we shall later 

 learn is very important. Moreover, it would be out of 

 the question for him to mulch all his fields in this way. 

 A mulch, then, of soil, or a dust mulch, as it is called, is 

 used. The following simple demonstration will show 

 how a dust, or powder, will prevent the moisture from 

 reaching the air : 



Place two lumps of sugar in a saucer containing a small 

 amount of water colored with red ink. On the top of one 

 of the lumps, place half a spoonful of powdered sugar, 

 soda or starch. Notice how the colored water comes to 

 the surface of the first lump and stops at the powdered 

 material in the second. 



QUESTIONS 



1. Name four ways by which water escapes from the soil. 



2. Which takes up water more rapidly, a sandy soil or a 

 clay soil? 



3. Which takes up water more rapidly, a soil rich in humus or 

 one lacking in humus ? 



4. Define the term spring. 



5. Explain what causes the water to issue from a spring. 



6. Explain fuUy how water enters a tile drain. 



