CONTENTS XXV 



bacteria. Decomposition of cellulose by thermophilic bacteria. Decom- 

 position of cellulose by denitrifying bacteria. Cellulose decomposition 

 by actinomyces. Cellulose decomposition by filamentous fungi. Cellulose 

 decomposition in manure. Importance of cellulose decomposition in 

 the soil. Influence of soil conditions upon cellulose decomposition. 

 Chemistry of hemicelluloses. Decomposition of hemicelluloses by micro- 

 organisms. Lignins, ligno-celluloses and their decomposition. Pectins, 

 mucilages and gums and their decomposition by microorganisms. Starches 

 and their decomposition by microorganisms. Decomposition of fats and 

 waxes. Decomposition of paraffins, aliphatic hydrocarbons and benzene 

 ring compounds in the soil. Decomposition of glucosides and monosac- 

 charides. Decomposition of organic acids 427 



Chapter XVIII 



DECOMPOSITION OF PROTEINS AND OTHER ORGANIC NITROGENOUS COMPOUNDS BY 



SOIL MICROORGANISMS 



Physical and chemical properties of proteins. Chemistry of protein hydrol- 

 ysis. Protein decomposition by microorganisms. Chemistry of ammonia 

 formation in the decomposition of proteins by microorganisms. Decom- 

 position of organic nitrogenous compounds of a non-protein nature. Am- 

 monia formation by bacteria. Ammonia formation by fungi and actinomy- 

 ces. Rate of ammonia formation by microorganisms and methods of 

 determinination. Nitrogen transformation in the rotting of manure. 

 Nitrogen transformation in the decomposition of organic matter in the 

 soil. Influence of nitrogenous decomposition products on the growth of 

 plants and microorganisms 470 



Chapter XIX 



INFLUENCE OF AVAILABLE ENERGY UPON THE TRANSFORMATION OF NITROGENOUS 

 COMPOUNDS BY MICROORGANISMS 



Carbon and nitrogen transformation by microorganisms. Influence of non- 

 nitrogenous organic compounds upon the decomposition of nitrogenous 

 compounds and upon the amounts of ammonia liberated. Decomposition 

 of organic substances of varying carbon-nitrogen ratio. Different groups 

 of microorganisms as affecting the carbon nitrogen ratio in the medium. 

 Influence of straw and plant residues upon the growth of cultivated plants . . 504 



Chapter XX 



OXIDATION PROCESSES — NITRATE FORMATION 



Oxidation-reduction phenomena. Oxidation processes in the soil. Source of 

 nitrates in the soil. Mechanism of ammonia oxidation. Mechanism of 

 nitrite oxidation. Nitrate formation from inorganic salts and from organic 

 nitrogenous compounds. Influence of reaction on nitrate formation. 

 Influence of organic matter upon nitrate formation. Influence of salts. 

 Influence of soil gases. Nitrate formation in solution and in soil. Influ- 

 ence of soil treatment upon nitrification in the soil. Oxidation of sulfur 

 and other minerals in the soil. Oxidation of organic compounds in the soil. 520 



