SOIL AND SUBSOIL. 



143 



station at Liebefeld, near Bern, it was found that in cultivated 

 soils the number of bacteria greatly exceeds the figures given 

 by Fraenkel. He found a gram of moist soil to contain from 

 three to fifteen millions of bacteria. In the cultivated soil of 

 Liebefeld he found 5,750,000, in meadow land 9,400,000, in a 

 manure pile 44,500,000 per cubic centimeter. These figures 

 seem high for so small a quantity of material, but taking the 

 average size of a bacterium, a cubic centimeter might readily 

 contain six hundred millions. (Grandeau, Ann. Sci. Agrono- 

 mique, vol. i, p. 461, 1905). 



Mayo and Kinsley (Rep. Kansas Exp't Station for 1902-3) have 

 made elaborate investigations of the numbers and kinds of bacteria 

 found in various soils in Kansas, in connection with different crops. 

 It is noteworthy that in most cases their figures exceed considerably 

 those given by European observers, as they often reach high into the 

 millions, in one case to over fifty millions, per cubic centimeter. 1 



Five fields with different soils were investigated ; the land being 

 described as follows : " Field No. i is a black loam containing con- 

 siderable humus ; field No. 2 is similar to field i but contains more 

 humus ; field No. 3 is a thin soil with clay gumbo subsoil ; fields Nos. 4 

 and 5 are black loams, but not as rich in humus as either No. i or 



No. 2." 



The average bacterial contents of the several fields are given as 



follows : 



Field No. i 33, 93 ! .747 P er cubic centimeter. 



No. 2 53,596,060 " " " 



" No. 3 78,534 " " 



" No. 4 8,643,006 " " " 



" No. 5 3.192,131 " " 



"The crop records of these fields for the past ten years indicate 

 that the crop yield has been (more or less ?) directly proportional to 

 the bacterial content of the soil of each field ; field 2 has produced the 

 largest yield, field 3 the least." 



Unfortunately no chemical analyses of any of these soils are com- 

 municated ; but at the request of the writer samples of the soils of the 



1 The mode of statement in the paper is not always quite clear as to the manner 

 in which the averages given were calculated. It must be remembered that these 

 data refer to cubic centimeters of soil, or about twice the amount (t gram) used 

 by European observers. 



