CONTENTS 



CHAPTER I 



PAGES 



CHARACTERISTICS OF SOILS ....... 1-28 



Chemical and physical composition of soils, 1 ; Phys- 

 ical condition of soil, 2. Temperature: Food require- 

 ments of plants, 3 ; Temperature and food preparation, 

 4 ; Chemical and physical activities, 5 ; Biological ac- 

 tivities, 6 ; Nitrogen preparation, 7 ; Temperature and 

 nitrification, 8 ; Nitrogen fixation, 9 ; Temperature and 

 germination, 10; Desirable temperature condition, 11; 

 Later effects, 12 ; A rare case, 13 ; Temperature and 

 root action, 14 ; Root pressure, 15 ; Root development, 

 16 ; Best temperature for root action, 17 ; Tempera- 

 ture and the rest-period, 18 ; Actual temperatures, 19. 

 Ventilation : Ventilation and food preparation, 20 ; 

 Prevention of food destruction, 21 ; Ventilation and 

 germination, 22 ; Ventilation and root action, 23 ; Re- 

 moval of objectionable products, 24. Soil Structure: 

 Ideal condition of structure, 25 ; Over-mellowness, 26 ; 

 Structure and germination, 27 ; Structure arid root 

 development, 28 ; Root development restricted by fis- 

 suring, 29 ; Injury to roots by fissuring, 30. Water : 

 Moisture and food preparation, 31 ; Moisture and ger- 

 mination, 32 ; Water the solvent and carrier, 33 ; Serv- 

 ice of water within the plant, 34 ; Quantities of water 

 required by crops, 35 ; Conditions of water, 36 ; Gravi- 

 tational water, 37 ; Capillary water, 38 ; Hygroscopic 

 water, 39; Movements of soil water, 40; Capillary 

 movements, 41 ; Surface tension, 42 ; Direction of cap- 

 illary movement, 43 ; Hygroscopic movements, 44. 



