774 



PRINCIPLES OF SOIL MICROBIOLOGY 



green manure itself. 21 The kind of manure greatly influences the 

 change in microbial activities. 22 



A close correlation was found between the bacterial numbers, am- 

 monifying power, nitrifying power and crop production of a soil receiv- 

 ing no manure, 5 tons and 15 tons of manure per acre. 23 The maximum 

 activities were obtained from the addition of the largest amounts of 

 manure; the increase from 20 inches of irrigation water was also most 

 marked in soil receiving the largest quantity of manure. Table 88 

 shows that the addition of manure to the soil results in an immediate 

 rapid increase in the numbers of microorganisms which reaches the 

 maximum in a few days, and is soon followed by a precipitous decrease 

 due to the rapid exhaustion of the available organic matter. 



TABLE 88 

 Influence of manure on the development of bacteria in the soil as determined by the 



plate method 2 ™ 

 (5 parts of manure per 100 parts of soil) 



Influence of temperature. Soil microorganisms are often divided 

 in respect to temperature, into three groups: 



1. Thermophilic, or those which require a high temperature for 

 their development, usually 45° to 65°C. 



21 Lemmermann, O., and Einecke, A. tlber die Wirkung einer Beigabe von 

 Stalldunger zur Griindungung. Mitt. deut. Landw. Gesell., 29 (Stiick 52): 

 702-704. 1914. 



22 Emmerich, R., Graf zu Leiningen, W., and Loew, O. tlber schadliche 

 Bakterientatigkeit im Boden und liber Bodensauberung. Centrbl. Bakt. Abt.. 

 II, 29: 668-683. 1911. 



23 Greaves, J. E., and Carter, E. G. Influence of barnyard manure and water 

 upon bacterial activities of the soil. Jour. Agr. Res., 6: 889-926. 1916; also 

 9: 293-341. 1917. 



23a Bright and Conn, 1919 (p. 41). 



