SUBJECT INDEX 



401 



Nitrification, supposed chemical origin, Nitrogen in soils, percentage present, 



23- 



two stages demonstrated, 23, 188. 

 Nitrifying power, 262, 300. 



Nitrites, assimilated by plants in small 

 quantities, 59. 



bacterial production from nitrates, 



208. 



- harmful in larger amounts, 85. 

 Nitrobacter. See Nodule organism. 

 Nitrogen, determination of, 348. 



evolution of gaseous, in decomposi- 



tion of organic matter, 191. 



fixation of, 182, 195. See also 



Nitrogen fixation. 



fixing power, 265. 



gaseous, supposed assimilation by 



plants, 14. 



supposed evolution from soil, 



182. 



in plant, association with calcium, 



nutrition, distinction between legu- 



minous and non - leguminous 

 plants, 18, 21, 24. 



recuperative agencies in soil, 182. 



source of, for vegetation, 10, 14 et 



seq., 18, 20. 

 content of soils; Broadbalk, 153, 



183. 

 relation to loss on ignition, 



335- 



upper and lower limits, 



184. 



Wilderness, 183. 



grain, effect of length of 



ripening period, 54. 



increased by magnesium 



oxide and car- 

 bonate, 75. 



sodium hydrate and 



carbonate, 73. 



unaffected by many salts, 



73- 

 . cycle in soils, 175, 178. 



fixation, attempts to induce in soils, 



2OI. 



by electric discharge, 196. 



free -living organisms 

 Algae, 200, 255- 



Azotobacter, 197. 



Clostridium, 196. 



- fungi, 259. 



nodule organisms, 25, 204. 



other organisms, 200, 208. 



in soil, 182. 



estimated amount of, 207. 



in soils, compounds present, 145. 

 loss of, 178, z8z. 



335- 



relation to fertility, 334. 



Nitrogenous nutrients for plants, 18, 



22, 57- 

 Nodule organism, artificial culture of, 



204, 206. 

 entry into plant, 205. 



isolation from soil, 205. 

 life cycle, 204. 



specific nature of, 25. 



stimulated by manganese com- 

 pounds, 207. 



Nodules on roots of leguminosae con- 

 tain bacteria, 21, 25. 

 Normal conditions in heavy soil, 249. 

 Nutrient solution, effect of concentra- 

 tion on plant growth, 238. 

 Nutrients become toxic when given in 

 larger quantity, 56. 



needed in large quantities, 56. 



small quantities only, 56, 



236. 



quantity absorbed by plants from 

 soil, 284, 357. 



raw materials out of which plant 



food is made, 55. 

 Nutrition of plants, effect of water 



supply, 38 et seq. 

 Nutritional disturbances in plants, 236, 



304- 



ORGANIC compounds absorbed and util- 

 ised by plants, 57. 



decomposition in soil, 212. 



effect on plants, 248. 



matter in soil, chemical properties 

 of, 138 et seq. 



colloidal properties of, 



130. 



decompositions, summary 



of, 214. 



determination of, 348. 



- effects of, 130, 329. 

 on fertility, 130, 



334- 

 on water supply, 



13*1 132. 



partially decom- 

 posed, 130. 



undecom po sed, 



130. 



fractionation of, 141. 



masks effects of clay and 



sand, 132. 



nature of, 129. 



original deposit, 129. 



recent formation, 129. 



26 



