CONTENTS 



CHAPTER I 



PAGES 



THE NATURAL FERTILITY OP THE SOIL AND SOURCES OF 



Loss OF THE ELEMENTS OF FERTILITY . . . 1-19 



Soil Fertility Chemical elements needed in plant 

 growth Fertility as influenced by water, climate and 

 season The influence of physical character of soil 

 Location of soil qualifies the term "fertility" Prac- 

 tical fertility is usable potential fertility . . . 2-6 



What Becomes of Our Fertility ? 7 



Sources of Natural Loss of Nitrogen Importance 

 of careful culture Loss of nitrogen by drainage 

 Escape of nitrogen into the atmosphere .... 8-11 



The Natural Loss of the Mineral Elements-^- Losses 

 due to mechanical means . . . . . 11-12 



Artificial Losses of Fertility A comparison of the 

 prices received for the fertility elements in different 

 crops Fertility content of cereals and vegetables 

 Irrational farm practice Losses in manures . . 13-19 



CHAPTER II 



THE FUNCTION OF MANURES AND FERTILIZERS, AND THE 



NEED OF ARTIFICIAL FERTILIZERS .... 20-35 



The Essential Elements of Fertilizers ... 20 



Natural Manures and Artificial Fertilizers . . 21 



Direct and Indirect Effect of Manures . . . 22-23 



Unavailable and Available Plant-food . . . 23-26 



Danger of Loss from the Use of Soluble Plant-food . 25 

 The Usefulness of a Fertilizer Constituent does not 



Depend upon Its Original Source 26 



Use of Fertilizers 27-28 



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