1 68 SOIL CONDITIONS AND PLANT GROWTH 



Nitrates as plant food, 31. 



— and plant growth, 16, 32, 33. 



— in soil, 73, 79. 



alleged catalytic formation of, 100. 



decomposition of, g8, 99. 



removal of, 80, 81. 



Nitrification, 15, 87 et seq. 

 Nitrogen cycle in soils, 79. 



— in soils, compounds present, 73. 



fixation of, 16, 83, 90, 95. 



loss of, 80 et seq., 89, 98. 



percentage present, 56, 85. 



Nitrogenous nutrients for plants, 9, 11, 12, 



14, 16, 30. 

 Northern climates, plant growth in, 36, 27. 

 Nutrients wanted in small quantities only, 



Organic matter in soil, effect of, 66, 138. 



fractionation of, 72. 



■ nature of, 65, 68. 



properties of, 66, 72. 



Oxygen supply, effect on seed and root, 23. 

 Oxidation in soil, 78. 



Pan, 69, 126. 



Partial sterilisation of soil, 114 et seq. 



Peat, 69. 



Phosphates and plant growth, 24, 36. 



— effect on plants, 37. 



— in soil, 145. 

 Photosynthesis, ig. 



Plant food, amount in soil, 108. 

 available, 108. 



— growth and various factors, 25 et seq. 

 effect on soil, 119. 



in relation to soil types, 120. 



Poisons, inorganic, effect on plant, 46 et seq. 



— organic, 113. 

 Pore space, 104. 



Pot cultures, introduction of, 4. 

 Potassium salts and plant growth, 40. 



effect on plants, 41. 



on soil, 144. 



Principle of vegetation, search for, 1. 

 Putrefactive power (Remy), 86. 



Rotation of crops, 3, 112. 



Saltpetre the principle of vegetation, 2. 

 Sand, composition of, 53. 



— effect in soil, 60. 



— properties of, 60. 

 Sandy soils, 125. 



Scouring land in Somerset, 128. 

 Silicates and plant growth, 46. 



— in soil, 57. 



Silt, composition of, 53. 



— effect in soil, 60. 



— properties of, 60. 



Sodium salts and plant growth, 42. 

 effect on supply of potassium salts, 



43> 55- 

 Soil analysis, 132 et seq. 



— constitution of, 52, 74, no. 

 American hypothesis, 76. 



— exhaustion, 129. 



— fertility, 129. 



— formation of, 51. 



— surveys, 132. 



— water, composition of, 63. 

 Sourness in soil, 62, 114. 



Sterilisation of soil. See partial sterilisation. 

 Strontium salts and plant growth, 45. 

 Sugar, effect on soil, 93. 

 Sulphates and plant growth, 46. 



Temperature and plant growth, 26. 



— of soil, 106. 



Tilth and compound particles, 121. 



— TuU on, 3. 



Topographical position and soil properties, 



120. 

 Toxins in soil, no et seq. 

 Translocation in plants, 20. 



Wasted fertility, 129. 



Water supply and plant growth, 27 et seq., 



139. 



and utilisation of food, 35. 



in soil, 102. 



available for plants, 104. 



Wax-like constituents of soil, 73. 



ABERDEEN : THE UNIVERSITY PRESS 



