CONTENTS. IX 



CUAPTER VI. 



The Soil as a Source op Food to Ckops : Ingredients whose Elements 

 ARE Derived from Kocks. 



§ 1. General View of the Constitution of the Soil as Related to Vegetable 



Nutrition 305 



i|§ 2. Aqueous Solution of the Soil 309 



§ 3. Solution of the Soil in Strong Acids 329 



§ 4. Portion of Soil Insoluble in Acids 330 



§ 5. Reactions by which the Solubility of the Elements of the Soil Is al- 

 tered. Solvent Effects of Various Substances. Absorptive and 



Fixing Power of Soils 331 



S 6. Review and Conclusion 361 



