CHAPTER XXVI 

 LIFE IN THE SOIL 



313. Questions for Discussion. 1. With your school ground or some 

 other known plot of ground as a basis for study, prepare a list of all 

 the living things you know which live on or within this piece of 

 ground. Then from your text or other source add to this list all the 

 microscopic forms which you think might live there. Js it true that 

 the soil teems with living things? 2. What is the relation of aphides 

 to the growth of a crop of corn? of ants to aphides? of the bird 

 known as the flicker to the ants ? Is the destruction of the flicker help- 

 ful or harmful to agriculture ? 3. How do bacteria affect the supply of 

 nitrogen in soils? 4. Why is it that nitrogen-producing bacteria are 

 not present in some old soils? 5. Why are bacteria necessary to the 

 best growth of clover, alfalfa, and cowpeas.? 6. From your state agri- 

 cultural experiment station get a bulletin which tells you the best ways 

 to plant clover, alfalfa, and cowpeas so as to insure the presence of the 

 proper bacteria. Make a class report upon this topic. 7. What is the 

 chief bacteria-using crop in your country? How long has this crop 

 been extensively grown? Are most farmers successful with it? How 

 could they be more successful ? 



314. Living things in the soil. We have already mentioned 

 some of the living things in the soil, but there are others, 

 chiefly microscopic, which need further discussion. There 

 are many small animals for example, the earthworms already 

 discussed the larvae of many kinds of insects, many adult 

 insects, and many microscopic animals of the lower forms of 

 life. In addition to the roots of living plants there are many 

 kinds of lower microscopic plants, chief of which are the 

 bacteria. These animals and plants live upon organic and 

 mineral matter in the soil, and not only through their life 

 processes but by the decay of their dead bodies they con- 

 tribute to the organic matter available for higher plants. 



312 



