352 



MICROBIOLOGY OF SOIL 



bogs and swamps. Hence the farmer attempts to intensify aeration 

 and the resulting mineralization of the humus by more thorough 

 tillage, drainage, liming and manuring. 



TEMPERATURE 



INFLUENCE OF CLIMATE AND SEASON. An illustration of the differ- 

 ences that may exist in the soil temperatures of different regions is given 

 by a comparison of the mean temperatures of 1901 recorded at Moscow, 

 Idaho, and New Brunswick, New Jersey. The soil temperatures were 

 taken to a depth of 152 mm. (6 inches). 



SOIL TEMPERATURE,* 1901 



AIR TEMPERATURE,* 1901 



It will be observed that in the months of November to March the 

 soil temperatures in the two places were nearly the same. On the 

 other hand, in April to October the average temperatures at New 

 Brunswick were for soil 14.5 (58F.) and for air 22.5 (72F.), re- 

 spectively; and in July they were 20.0 (68F.) and 24.5 (76.4^.) 

 respectively. It will also be observed that there is an unmistakable 

 relation between the corresponding air and soil temperatures. 



As a further illustration of the relation of climate to temperature a 

 comparison may be made of the average daily mean temperatures at 

 Bismarck, North Dakota, for the period 1873-1895, and at Key West, 

 Florida, for the period 1872-1895. 



DAILY MEAN TEMPERATURES* (AIR) 



* Recorded in Fahrenheit scale. 



