894 



INDEX 



Soil, aerobic activities, 294 

 algae in, 305 

 aluminum in, 362 

 ammonia formation, 331 



transformation, 336 

 ammonification, 322 



climatic conditions influencing, 



323 



efficiency, 326 



of difiEerent species, 326 



experimental study, 322 



mechanism of, 323 



molds, 303 



numbers involved, 325 



species involved, 325, 

 anaerobic activities, 294 

 bacteria, 308 



aerobic species, 340 



anaerobic species, 340 



at different depths, 309 



distribution, 309 



groups (morphological and 

 physiological), 310 



methods of study (quantita- 

 tive and qualitative), 311 



nitric, 329 



nitrous, 329 



number, 308 



productive soil, 308 



unproductive soil, 308 



in water, 256 

 bacterial substance available, 336 



substance present, 335 

 biological factors of soil-forma- 

 tion, 354 , 

 calcium, 314, 354 

 carbohydrates (origin), 315 

 carbon dioxide in, 394 

 carbon-mtrogen ratio, 321 

 climatic influences, 295 

 composition (mechanical), 293 

 copper, 362 

 cultures for soil, 352 

 denitrification, 333 



environmental relations, 335 



experimental study, 333 



Soil, drought, 292 

 early, 297 

 fermentations, cellulose, 303, 315 



fats, 318 



fixation of nitrogen, 338 



organic matter, 289 



proteins, 320 



starches, 317 



sugars, 317 



waxes and gums, 318 

 food (plant) assimilation of, 297 



(plant) production in, 297 

 formation of, 354 

 general discussion, 289 

 higher plants in, 308 

 infection, 666 

 inoculation, 352 

 iron, 361 ^ 



late, 297 



magnesium, 354, 356 

 manganese, 314, 362 

 , medium, as culture, 290 

 mineral food, 300 

 mineralization of organic matter, 



295 



moisture relations, 290 

 rainfall, 291 

 range of, 291 



molds in, 302 



nitrates, transformation of, 336 



nitrification, 327* 



bacteria (nitric and nitrous), 



329 

 environmental relations, 329 

 experimental study, 327 

 nitrates, accumulation, 332 

 disappearance, 332 



nitrogen, addition to, 314 



nitrogenous compounds, trans- 

 formation of, 336 



nitrogen (atmospheric) fixation, 

 aerobic species, 303, 340 

 anaerobic! species, 340 

 biological relations, 339 

 chemical relations, 339 

 cultures for inoculation, 352 



