332 GENERAL SCIENCE 



17. Of what nature is the "rust" on wheat? What harm results from it? 

 What is meant by parasitic plants? What course may be pursued to save 

 wheat from rust? What treatment of seed wheat may be employed to 

 lessen "smut?" 



ORIGIN AND NATURE or SOILS 



To the careless and indifferent mind the term soil may have 

 little significance. As dust it gets into our eyes, and it makes 

 the life of the house-keeper a burden. As mud it clings to 

 one's shoes, and it makes travel and transportation by high- 

 ways both irksome and expensive. To the botanist, how- 

 ever, soil is the source whence the higher types of plants get 

 their food material in large part, and in which the mightiest 

 oak and the tiniest violet alike find root. To the zoologist 

 it is the abode of innumerable forms of animal life. To the 

 farmer engaged in raising crops the depth, the texture, and 

 the chemical nature of the soil tilled by him is of utmost 

 importance. He must have knowledge of the kind of crops 

 likely to be most productive. He must learn ways of con- 

 serving the fertility of the soil, and of managing it most 

 profitably. Courses in agricultural colleges involving a 

 study of the origin of soils, their waste and restoration, their 

 characteristics and management, and the effect upon soil 

 structure of plant and animal life, require a knowledge of 

 Chemistry, Geology, Physical Geography, and Physics. 



In an attempt to classify and name soils, no mere descrip- 

 tion can take the place of actually handling some well-chosen 

 types, and of learning through first-hand acquaintance to 

 recognize and name all local varieties of soil. Very largely 

 soils may be described by making combinations of the terms 

 gravel, sand, clay, and loam, along with descriptive adjectives 

 advisedly chosen, e.g., a light sandy loam, a stiff clay soil. 

 Silt is composed almost exclusively of very fine particles of 

 earthly material such as the sediment from running waters 

 when their current is checked. When dry it crumbles read- 



