14 SOILS 



inches to many feet, have a pronounced effect upon 

 the texture of the soil, and upon its aeration. 



The burying beetle, crayfish, woodchuck, chip- 

 munk, mole, gopher, prairie dog, ground squirrel, 

 badger, and other burrowing animals and insects, 

 all contribute largely, in the aggregate, to the move- 

 ment and aeration of soils, the Tatter four being 

 especially abundant west of the Mississippi. Go- 

 phers have honeycombed millions of acres, and 

 prairie dogs and ground squirrels have been no 

 less industrious. However injurious these animals 

 may be otherwise, and however difficult may be 

 the task of exterminating them so that crops can 

 be grown, they certainly serve a useful purpose in 

 mixing the subsoil with the surface soil and pro- 

 moting better drainage and aeration. Thousands 

 of acres of land in the United States have been 

 submerged by the erection of beaver dams and 

 their value for agricultural purposes has been pro- 

 foundly influenced thereby. The beaver is no 

 longer an important factor in soil building with us, 

 but he has contributed very largely in the past. 



The Important Service of Angleworms. The 

 most important soil builder among animals is the 

 angleworm or earthworm. Of these there are 

 many kinds, from the big, snaky "night walker," 

 that the fisherman with a torch finds crawling along 

 the ground at night, to the tiny red ones beneath 

 the pile of old manure. In South Africa some 

 earthworms are two feet long. All of them are 

 most industrious soil workers. After a rainy night, 

 especially in early spring, the ground may be 

 thickly strewn with their castings. On digging 

 down in most moist soils a labyrinth of angleworm 

 channels will be found. These burrows go more 

 than five or six feet below the surface. 



