CONTENTS 



PAGE 



INTRODUCTION xvii 



PART I. SCIENCE AND SOIL 



CHAPTER 



I. FOUNDATION FACTS AND PRINCIPLES i 



II. THE MORE IMPORTANT ELEMENTS AND COMPOUNDS . . .12 



III. PLANT FOOD AND PLANT GROWTH 26 



IV. THE EARTH'S CRUST 46 



V. SOIL FORMATIONS AND CLASSIFICATIONS 54 



VI. SOIL COMPOSITION . . . 58 



VII. AVAILABLE PLANT FOOD 107 



VIII. SOIL SURVEYS BY THE UNITED STATES BUREAU OF SOILS . .114 

 IX. SOIL ANALYSES BY THE UNITED STATES BUREAU OF SOILS . 136 

 X. CROP REQUIREMENTS FOR NITROGEN, PHOSPHORUS, AND PO- 

 TASSIUM 153 



XI. SOURCES OF PLANT FOOD 156 



PART II. SYSTEMS OF PERMANENT AGRICULTURE 



XII. LIMESTONE 160 



XIII. PHOSPHORUS 183 



XIV. ORGANIC MATTER AND NITROGEN 194 



. XV. ROTATION SYSTEMS FOR GRAIN FARMING 226 



XVI. LIVE-STOCK FARMING 231 



XVII. THE USE OF PHOSPHORUS IN DIFFERENT FORMS . . . ^236 



XVIII. THEORIES CONCERNING SOIL FERTILITY 300 



PART III. SOIL INVESTIGATIONS BY CULTURE EXPERIMENTS 



XIX. THE ROTHAMSTED EXPERIMENTS 344 



XX. PENNSYLVANIA FIELD EXPERIMENTS 420 



XXI. OHIO FIELD EXPERIMENTS 441 



XXII. ILLINOIS FIELD EXPERIMENTS 453 



XXIII. FIELD EXPERIMENTS IN THE SOUTH, INCLUDING SOUTHERN 



ILLINOIS 476 



ix 



