SUBJECT INDEX 



397 



Catalytic actions of soils, 215. 



Cellulose, decomposition in soil, 177. 



by fungi, 258. 



by Spirochaeta cyto- 



phaga, 177. 



Chalk soils, 120, 306 et seq. 



Charlock, spraying for, 83. 



Chemical analysis of soil, ^33, 



Cheshunt Experimental Station, 71. 



Chlorides and plant growth, harmful in 

 larger amounts, 73, 75, 

 76. 



necessary in small quan- 

 tities, 56. 



Chlorophyll a magnesium compound, 



75- 

 Chlorosis, 86, 304. 

 Clay as electro-negative colloid, 104, 



161. 

 semi-permeable. membrane, 105. 



— colloidal (Schloesing's) preparation 



of, 148. 



— composition of, loi et seq. 



— definition of, 104. 



— effects in soil, 106. 



— justification of British definition, gg. 



— particles, constitution of, 162. 

 — • properties of, 104 et seq. 



— re ation to K._,0 content, 340. 



— soils, 310. 



characteristics of plant growth 



on, 312, 

 need some excess of calcium 



carbonate, iig, 336. 

 water supply in, 2ig. 



— two groups of, loi. 

 Climate and crops, 45. 



— a factor in determining soil type, gg, 



303- 



fertility, 331. 



Clostridium and azotobacter, relative 



distribution of, 204. 

 Coarse sand, composition of, 102. 



effect in soil, 108. 



properties of, 108. 



Coastal soils, loi. 

 Colloidal clay, preparation of, 148. 

 Colloids in soil, effect in determining 

 plant habitats, 23g. 



estimation of, i6g. 



importance, i4g, 172. 



influence on micro-organ- 

 isms, 23g. 

 reactions, 168. 



— properties of, 148. 



Competition between plants, effect on 

 flora, 241. 



balance in, 241. 



Composition of soil particles, 102. 



Compound interest law (V. H. Black- 

 man), 28. 

 Compound particles in soil, 170, 171, 



303- 

 Condition and fertility, 320. 

 Constitution of clay, 162. 



soil, 170. 



— particles, 172. 



Cooper- Hewitt mercury lamp and plant 



growth, 88. 

 Copper salts harmful to plant growth, 83. 



use as plant poisons, 83. 



Crenic acid, 141. 



Crops, distribution of; influence of 



rainfall, 45. 

 temperature, 45. 



— specially suited to certain soils, 240. 

 Cultivation, exhaustion due to continu- 

 ous, 321. 



— loss of nitrogen during, 181. 



Decomposition of organic matter in 



soil, 175 et seq. 

 Deflocculation, See Flocculation. 

 Denitrification, 208. 



— not extensive in normal soils, 2og. 

 Depth of soil, importance of, 306. 

 Dicyanodiamide, toxic to plants, 85. 

 Disease organisms in soil, 253. 



— resistance as affected by soil con- 



ditions, 53, 61, 70, 71. 

 Dominant constituents of fertilisers, 



ig. 

 Drainage water, composition of, 127, 

 152. 



— — nitrogen lost in, 178, agg. 

 Dried soil and productiveness, i6g. 

 Drought, effect on soil reactions, 275. 

 Dry farming, 218. 



Earth the " principle " of vegetation, 



4- 

 Earthworms in soil, action of, 136, 137. 

 Ecological classification of humus, 133. 

 Ecology, province of, 43. 

 Edinburgh Society for Improvement of 



Arts, 6. 

 Eelworms in soil, 253. 

 Efficiency values of plant nutrients 



(" Wirkungswert"), 33. 

 Elective method, ig6. 

 Electric discharge, effect on plant 



growth, 87. 

 Electrolytes, effect on clay, 105. 

 Electro-osmosis, 161. 

 Emulsoids, 160. 

 Energy relationships ; micro-organisms, 



i2g, 252, 272. 

 ammonifying, 186. 



