190 



INDEX 



Mechanical analysis of soil, interpretation of, 

 157. 



fractions obtained during, 54. 



methods, 173. 



Methods of investigation, correlation, 60, 68. 



statistical, 6, 8. 



Micro-organisms in soil, active and resting 

 stage, 117. 



groups of, 118. 



methods of investigation, 120. 



Mineral part of soil, 54. 

 Minimum, law of, u, 23. 

 Moisture in soil, amounts of, 105. 

 Mycorrhiza, 119. 



NITRATES and plant growth, 16, 32, 33. 



as plant food, 31. 



formation in soil, 130. See also Nitri- 



fication. 

 effect of growing plant, 137. 



in soil, 75, 81, 123. 



alleged catalytic formation of, 102. 



decomposition of, 100, 101. 



removal of, 82. 



Nitrification, 15, 88 et seq. 

 Nitrifying power, 121. 

 Nitrogen cycle in soils, 81, 102. 



fixing power, 122. 



gaseous, supposedassimilation by plants, 



1 6. 



in soils, compounds present, 74. 



fixation of, 16, 85, 92, 97. 



loss of, 81 et seq., 91, 101. 



percentage present, 57, 87. 



Nitrogenous nutrients for plants, 9, n, 12, 



14, 16, 30, 119. 



Northern climates, plant growth in, 26, 27. 

 Nutrients wanted in small quantities only, 



112. 



ORGANIC; matter in soil, effect of, 68, 158. 



fractionation of, 73. 



nature of, 66, 70. 



properties of, 68, 73. 



Oxygen supply, effect on seed and root, 25. 

 Oxidation in soil, 80. 



PAN, 70, 146. 



Partial sterilisation of soil, 130 et seq. 



Peat, 71. 



Phosphates and plant growth, 24, 36. 



effect on plants, 37. 



in soil, 166. 

 Photosynthesis, 19. 



Physiological grouping of soil organisms, 120. 

 Plant food, amount in soil, no. 

 available, no. 



growth and various factors, 25 et seq. 



effect on soil organisms, 136. 



in relation to soil types, 147. 



Poisons, inorganic, effect on plant, 47 et seq. 



Poisons, organic, 115. 



Pore space, 106. 



Pot cultures, introduction of, 4. 



Potassium salts and plant growth, 41 



effect on plants, 41. 



in soil, 165. 



Principle of vegetation, search for, I. 

 Protozoa in soil, 134, 136. 

 Putrefactive power (Remy), 121. 



ROTATION of crops, 3, 113. 



SALTPETRE the principle of vegetation, a. 

 Sand, composition of, 54. 



effect in soil, 60. 



properties of, 60. 

 Sandy soils, 125. 



Scouring land in Somerset, 128. 



Seasonal effects on bacterial activity in soil, 



128. 



Sickness in soil, 135. 

 Silicates and plant growth, 46. 



in soil, 57. 



Silt, composition of, 53. 



effect in soil, 62. 



properties of, 62. 

 Silty clays, 145. 



Sodium salts and plant growth, 43. 



effect on supply of potassium salts, 



43, 56. 

 Soil analysis, 153 et seq. 



constitution of, 52, 76, 112. 

 American hypotheses, 78, 115. 



exhaustion, 150. 



fertility, 150. 



formation of, 52. 



surveys, 153. 



water, composition of, 65. 

 Sourness in soil, 63, 116. 



Sterilisation of soil. See Partial sterilisation. 

 Strontium salts and plant growth, 45. 

 Sugar, effect on soil, 95. 

 Sulphates and plant growth, 46. 



TEMPERATURE and plant growth, 26. 



of soil, 108. 



and bacterial activity, 126, 127. 



Tilth and compound particles, 141. 



Tull on, 3. 



Topographical position and soil properties, 



140. 



Toxins in soil, 115. 

 Translocation in plants, 20. 



WASTED fertility, 150. 



Water supply and plant growth, 27 et seq., 



159- 



and utilisation of food, 35. 



in soil, 105. 



available for plants, 106. 



Wax-like constituents of soil, 74. 



ABERDEEN : THB UNIVERSITY PRESS 



