Contents 



CHAPTER 



1 • Historical 1 



2 • The microbiological population of the soil as a whole . 29 



3 • Occurrence of specific microorganisms in the soil ... 59 



4 • Decomposition of plant and animal residues in soils and in 



composts 95 



5 • Humus: nature and formation 124 



6 • Decomposition of soil organic matter and evolution of car- 



bon dioxide 149 



7 • Transformation of nitrogen in soil; nitrate formation and 



nitrate reduction 166 



8 • Nitrogen fi.xation— nonsymbiotic 191 



9 • Nitrogen fixation— symbiotic 20S 



10 ■ Transformation of mineral substances in soil by micro- 



organisms 230 



11 • Higher plants and soil microorganisms 246 



12 • Associatixe and antagonistic effects of soil microorganisms 261 



13 ■ Disease-producing microorganisms in the soil and their 



control 282 



14 • Stable manures, composts, and green manures 303 



15 • Microorganisms and soil fertility 323 



16 • Recent developments in soil microbiology .... 337 



Index 347 



vu 



