INDEX 



259 



Soil, environment, effects on soil mi- 

 crobes, 240-241 

 fertility, biological estimation of, 



234-240 

 formation, 9-10, 179 

 gases, composition of, 159 

 horizons, 1, 2, 3 

 humus, formation of, 99-101 

 inoculation, 125, 203, 229-234 

 mechanical analysis of, 6 

 mineral and chemical composition 



of, 4-7 

 moisture and numbers of micro))es, 



61-63 

 morphology, 1-2 

 nature of, 1-6 

 nitrogen, influence of legumes on, 



124 

 organic matter, 11-12 

 phases, 12-13 

 population, 41-42, 44-74 



modification of, 74, 203-241, 

 242 

 profile, 1, 2 

 reaction, 17 



change of, by microbes, 166-167 

 influence of nitrification on, 142 

 treatment, influence of, upon dis- 

 tribution of bacteria, 58-60 

 Soils, nitrogen content of, 103 

 Solid phase of soil, 12 

 Solution method, 55 

 Spirilla, 29 



Spirillum desulfuricans, 29, 172 

 Staining of microbes, 50-52 

 Starch, decomposition of, 81 

 Straw, nitrogen assimilation during 



decomposition of, 95-96 

 Sugars, decomposition of, 79-81 

 products of aerobic decomposition 



of, 80-81 

 products of decomposition of, by 

 bacteria, 80-81 

 Sulfate utilization by microorganisms, 



168 

 Sulfates, influence of, on soil microbes, 



222-223 

 Sulfides in soil, 169, 170 



Sulfur, elementary, oxidation of, in 

 soil, 170 

 in plant nutrition, 14 

 in plant residues, 168 

 in soil, 16, 18, 168 

 oxidation of, 148 

 reduction of, in soil, 172 

 transformation of, by microbes, 



167-173 

 use of, to control soil reaction, 221, 

 231-232 

 Sulfur bacteria, inoculation of soil 



with, 229, 232 

 Sulfuric acid production in soil, 157 

 Symbiosis, 41, 117, 125 

 Symbiotic nitrogen-fLxing bacteria, 



105, 113-126 

 Synthesis, by microbes, influence of 

 organic matter on, 93-99 

 by soil microbes, 245-247 

 influence of cellulose on, 84-85 

 of hemicelluloses by microorgan- 

 isms, 81-82 

 Synthetic processes of microbes, 14 



Temperature, influence of, on carbon 

 dioxide in soil, 160 

 on nitrogen content of soil, 8 

 Thermophihc bacteria, 31 

 Thiobacillus group, 170 

 Thiobacillus thiooxidans, 28, 231 

 Toxins, plant, decomposition of, 90 

 Trichoderma, 32, 34 

 Trophic state of protozoa in soil, 70 



U 



Ultramicroscopic organisms, 29 

 Urea, decomposition of, 129-130, 212, 

 216 

 oxidation of, 163 

 Uric acid, decomposition of, 129 



Vahlkampfia soli, 41 

 Vibrios, 29 



