496 



PRINCIPLES OF SOIL MICROBIOLOGY 



will influence greatly the rate of the reaction. Gainey 68 observed a 

 remarkable similarity in the rates of formation of ammonia and car- 

 bon dioxide from dried blood and cotton seed meal. At first there was 

 a rapid increase which soon reached a maximum and then decreased 

 rapidly. Insufficient aeration and moisture resulted in a decrease in 

 ammonia formation. Unfavorable conditions had a more detri- 

 mental effect on the latter than on C0 2 evolution (fig. 28). An in- 

 teresting correlation was found 69 between the amounts of ammonia 



Fig. 28. Rate of decomposition of cottonseed meal in soil, as shown by the 

 evolution of CO2 and accumulation of NH3; 1 and 2 were aerated continuously, 

 S and 4 were aerated 30 minutes daily (from Gainey) . 



formed and the numbers of bacteria, as a result of addition of organic 

 matter to the soil. 



The literature on the subject of ammonia formation from the de- 

 composition of nitrogenous organic substances added to the soil is 

 very extensive. Unsuccessful attempts were even made to determine 



88 Gainey, 1919 (p. 685). 



89 Beckwith, T. D., Vass, A. F., and Robinson, R. H. Ammonification and 

 nitrification studies of certain types of Oregon soils. Ore. Agr. Exp. Sta. Bui. 118. 

 1914. 



