READING-LESSON 



CORNKLIv READING-COURSE ^^ ^ 



FOR FARMERS. January, i899. 



Bv G. W. CAVANAUGH. 



Fertility of the Soil : What it is. 



1 . To be fertile, a soil must contain plant-food. — All plants during 

 growth absorb certain substances from the soil. Those substan- 

 ces which are essential for the best growth and development of 

 the plant are called plant-foods. These are iron, lime, potash, 

 sulfur, silica, nitrogen, phosphoric acid, and six or seven 

 more. 



2. The different plant-foods are equally essential. — A plant must 

 have each and every one of the different plant-foods. Each is 

 essential to aid in some particular function, and no one can be 

 substituted for another. If a soil were to contain all the other 

 plant-foods and be lacking in phosphoric acid it could not be a 

 fertile soil. It could not grow plants because phosphoric acid 

 is necessar}^ in the development of a plant, and no other sub- 

 stance is known that will take its place. The same remarks 

 might be made respecting iron, lime, silicon, or the others. 



3. The different pla7it-foods are zvidely distributed in nature. — 

 A soil on which are growing only mulleins, moss or daisies, is 

 usually not considered a fertile soil ; and yet the fact that these 

 plants grow shows that the soil contains the different elements 

 of plant-food, at least to some extent. In such a case, the rela- 

 tive infertility is as likely to be due to the texture of the soil, or 

 to its lack of moisture-holding capacity, as to a deficiency of min- 

 eral plant-food. A soil which is practically worn out for onions, 

 may still grow rj^e or smartweed. See Lesson i. 



4. The element of which there is relatively the least, deterynines 

 the productive power of the soil {so far as plant-food is concerned) . — 

 It may be that some one element is present only to a limited ex- 

 tent, in which case it will measure the producing power of the 



