v 



TABLE OF CONTENTS 



Composition of glacial soils, 40 Humus of glacial 

 soils, 41 Glacial lakes, 42 Lacustrine soils glacial 

 lake, 43 Lacustrine soils recent lake, 44 JEolian 

 soils, 45 Loess soils, 46 Distribution of loess, 47 

 Adobe soils, 48 Sand dunes, 49 Volcanic dust, 60. 



CHAPTER V 

 CLIMATIC AND GEOCHEMICAL RELATIONSHIPS OF SOILS . 65-82 



Climatic relationships, 51 Geochemical relationships 

 of residual and marine soils, 52 Residual and glacial 

 soils, 53 Effect of glaciation on agriculture, 54 Hu- 

 mid and arid soils, 55 Soil color, 56 White and 

 black soils, 57 Red and yellow soils, 58 Agricul- 

 tural significance of color, 59 Soil and subsoil, 60 

 Soil and subsoil of humid regions, 61 Soil and subsoil 

 of arid regions, 62. 



CHAPTER VI 

 SOIL PARTICLE ........ 83-107 



Soil separates and mechanical analysis, 63 Princi- 

 ples of mechanical analysis, 64 Mechanical analysis 

 by water in motion. Schone elutriator, 65 Hilgard's 

 churn elutriator, 66 Yoder's centrifugal elutriator, 67 

 Mechanical analysis by water at rest Osborne's 

 beaker method, 68 Atterberg's modified Appiani silt 

 cylinder, 69 Centrifugal soil analysis, 70 Classifica- 

 tion of soil particles, 71 Bureau of Soils classification, 

 72 Physical character of the separates, 73 Mineral- 

 ogical characteristics of the separates, 74 The chem- 

 ical constitution of soil particles, 75 Value of a 

 mechanical analysis, 76 Soil class, 77 Determination 

 of class, 78 The significance of texture and class, 79. 



CHAPTER VII 



PHYSICAL PROPERTIES OF THE SOIL .... 108-126 

 Arrangement of soil particles, 80 The absolute spe- 

 cific gravity of the soil, 81 Apparent specific gravity, 



