256 



INDEX 



Nitrification, influence of aeration on, 

 137-139, 142-143 

 influence of ammonia on, 140-141 

 influence of moisture on, 143-144 

 influence of plants on, 145 

 influence of organic matter on, 143, 



146 

 influence of reaction on, 137-142 

 Nitrifying bacteria, abundance of, in 

 soil, 138 

 influence of partial sterilization on, 



138-139 

 influence of reaction on, 220-221 

 occurrence of, 137-138 

 Nitrobacter, 27 



Nitrogen, absorption of, by plants, 17 

 amounts of, fixed by non-symbiotic 

 bacteria, 110-111 

 fixed by symbiotic bacteria, 120- 

 124 

 assimilation of, by bacteria, in- 

 fluence of cellulose on, 95-96 

 by fungi, influence of cellulose on, 



83-84, 95-96 

 during decomposition of organic 

 materials, 94-100, 132-135 

 changes during decomposition, 97- 



99 

 content, of microbial cells, 94-95 

 of organic matter, influence of, on 

 products of decomposition, 

 95-100, 132-135, 146 

 of soil, 8, 103 

 importance in nutrition of microbes, 



26 

 in animal manure, 210-216 

 influence of, on cellulose decompo- 

 sition, 83, 84 

 inorganic, removal of, from soil, 



103 

 in plant nutrition, 14, 15 

 in soil, 16 



loss from soil, 145-152, 247 

 losses from animal manure, 213-214 

 organic, added to soil, 103-104 

 role of microbes in transformations 



of, 104-105 

 soil, availability of, 102-103 



Nitrogen, soil, influence of decom- 

 position of organic matter 



on, 92-101 

 sources of, in soil, 102-104 

 transformation of, by soil microbes, 



102-153, 247 

 Nitrogen-fixation, 104-126, 194, 247- 



248 

 by blue-green algae, 106 

 by nodule-forming bacteria, 105, 



113-126 

 correlation with growth of bacterial 



cells, 106-108 

 factors associated with, 107 

 influence of glucose on, 107 

 influence of nitrates on, 110, 120- 



124 

 influence of phosphorus on, 113 

 influence of reaction on, 111-113, 



124-125 

 influence of soil conditions on, 



124-126 

 non-symbiotic, importance of, 109- 



112 

 soil factors favoring, 111-113 

 symbiotic, biological nature of, 



113-114 

 symbiotic, mechanism of, 117-118 

 Nitrogen-fixing bacteria, influence of, 



on plant growth, 114-126 

 influence of reaction on, 220 

 non-symbiotic, 104-113 

 soil inoculation with, 125 

 sources of energy available to, 109 

 symbiotic, 105, 113-126 

 Nitrosomonas europea, 26 

 Nitric acid, action of, on phosphates, 



162-163 

 in soil, 161-163 

 production in soil, 157 

 Nitrite, formation from ammonia, 



136-145 

 occurrence in soil, 141 

 Nodule bacteria, 105, 113-126 



nitrogen fixation by, 105, 113-126 

 specificity of, 119-120 

 Nodule formation, 200 

 Nodules of legumes, 118-119 



