CONTENTS 



IX. SUB-PROVINCES, CLASSES, TYPES, AND SURVEYS 112 



Sub-provinces Soil Classes Soil Types Naming of Soil 

 Types Classes, Types, and Phases in Illinois Soil 

 Surveys Surveys in Different States Objects of a Soil 

 Survey Methods of the Survey Sampling of Soils. 



X. MINERAL CONSTITUENTS 123 



Soil Particles and Their Separation Mechanical or Physi- 

 cal Analysis Methods of Mineral Soil Constituents and 

 Their Properties Colloids Colloids in Soils Mineral 

 Colloids Clays and Clay Loams Silt and Silt Loams 

 Sands and Sandy Loams Gravel and Gravelly Loams 

 Stones. 



XI. ORGANIC CONSTITUENTS OF SOILS 142 



Kinds of Organic Matter Amount of Organic Matter in 

 Soils Changes of Organic Matter Nitrogen Content of 

 Humus Distribution of Organic Matter in the Soil Strata 

 Value of Organic Matter to Soils Losses of Organic 

 Matter Estimation of Organic Matter. 



XII. MAINTAINING AND INCREASING THE ORGANIC-MATTER 



CONTENT OF SOILS 158 



Addition of Limestone Application of Phosphorus 

 Accumulations in PasturesGreen Manures Catch and 

 Cover Crops Barnyard Manures Loss of Manure and 

 Its Prevention Methods of Applying Manure Organic 

 Residues Growing Non-tilled Crops Rotatio nof Crops. 



XIII. PHYSICAL PROPERTIES OF SOILS 175 



Real or Absolute Specific Gravity Apparent Specific 

 Gravity Weight of the Soil Color of Soils Odor of Soils 

 Number of Particles Shape of Particles Arrangement 

 of Particles Internal Area of Surface Porosity of Soils. 



XIV. WATER OF SOILS 186 



Some Physical Characteristics of Water Specific Heat 

 Viscosity Uses of Water Amount of Water Required 

 by Plants Dependent Upon Transpiration Supply of 

 Moisture in Soils Ways of Expressing Moisture Content. 



XV. WATER OF SOILS. I. HYGROSCOPIC MOISTURE 194 



Determination of Hygroscopic Coefficient of Soils Use of 

 Hygroscopic Moisture. 



XVI. WATER OF SOILS. II. CAPILLARY WATER 199 



Surface Tension Moisture in Soil Columns Effect of 

 Size of Soil Particles Moisture Equivalent Determina- 

 tion of Moisture Equivalents from Other Soil Constants 

 Movement Thickness of the Film Viscosity Texture 

 Organic Matter Maximum Capillary Capacity or Moist- 

 ure-holding Capacity of Soils Amount of Water Moved 

 by Capillarity The Capillary Pull of Soils Osmosis in 

 Soils Use of Capillary Water Wilting Coefficient 

 Available Moisture. 



XVII. WATER OF SOILS. III. GRAVITATIONAL WATER 217 



Percolation Physical Composition or Texture Granula- 

 tionOrganic Matter Viscosity Atmospheric Pressure 

 Shrinkage Cracks Roots of Plants Lysimeters or 

 Drain Gages. 



