100 TALKS ABOUT THE SOIL. 



xx. FERTILIZERS. When all the fourteen or 

 seventeen elements are present in abundance in any 

 soil, we say it infertile. It must be noticed, however, 

 that in nearly all poor or unfertile soils we shall find it 

 is only three of these elements that are usually missing, 

 the others being everywhere abundant. When one or 

 more of these elements are missing, and we add any 

 thing containing the missing elements, we call the 

 material, whatever it may be, a fertilizer. Fertilizers 

 include plants, seeds and parts of plants, waste matter 

 from animals, the remains of creatures of every kind, 

 fish, bones, hair, shells, etc., rocks containing remains 

 of animals or particular elements, and waste materials 

 from shops and works of every kind. For conven- 

 ience, fertilizers are divided into three classes : first, 

 living plants or green manure ; second, waste matter 

 from animals, or manure ; and, third, all those various 

 materials, ground bones, crushed rock, prepared 

 chemicals, blood and slaughter-house waste, saltpetre, 

 potash salts, and phosphatic rock and waste matter 

 from some kinds of manufactories, all of these 

 receiving the' general name of commercial fertilizers. 



Let us return a moment, and recall the elements 

 needed by plants, and that are to be found in greater 

 or less quantities in any rich and fertile soil. These 

 elements are oxygen, hydrogen, nitrogen, carbon, sili- 

 con, sulphur, phosphorus, chlorine, potassium, sodium, 

 calcium, magnesium, aluminium, and iron. There are 

 also three more, manganese, iodine, and fluorine ; 

 but the first fourteen are the most important, and of 



