1912. 



PUBLIC DOCUMENT — No. 31. 



131 



decoctions correspond with the increase and decrease of ammonia 

 content in each case, more ammonia being found in the decoc- 

 tions which possessed the largest number of bacteria. This fact 

 is not new, as it has been shown by Russell and Hutchinson in 

 recent years. 



Table VI. — Showing Comparison between the Amounts of Ammonia in 

 Decoctions of Sterilized and Unsterilized Loam and Subsoil. {Inocu- 

 lations made with Ordinary Soil Bacteria.) 



Soil. 



Amount op Ammonia in Decoction of 100 

 Cubic Centimeter8 (Grams). 



Experiment 1. Experiment 2 



Average. 



Sterilized loam, 

 Unsterilized loam, . 

 Sterilized subsoil, 

 Unsterilized subsoil, 



.0050 

 .0031 

 .0020 

 .0030 



.0050 

 .0032 

 .0021 

 .0032 



.0050 

 0031 

 .0020 

 .0031 



Table VII. — Showing Comparison between the Amount of Ammonia in 

 Decoctions of Sterilized and Unsterilized Loam and Subsoils. {Inocvr 

 lations made with Water Cidtures of B. subtilis.) 



Experiment 1. 



This increase in the amount of ammonia in each case is cer- 

 tainly brought about by the action of the bacteria upon the 

 organic matter in the soil, l^ow the question arises : What 

 change takes place within the soil, when sterilized, in order to 

 produce this increase in the number of bacteria ? In the case of 

 the subsoil, where the increase takes place in the unsterilized 

 soil, it is a question as to what change takes place upon sterilizing 

 that has a detrimental effect on bacteria. 



Russell and Hutchinson ^ tried the effect of untreated soil 



' The Effects of Partial Sterilization of Soil on the Production of Plant Food, by E. J. Ruasell 

 and H. B. Hutchinson, Journal of Agricultural Science, Vol. III., Part II., October, 1909, p. 117. 



