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 nnniber of bacteria. This fact 

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

 recent years. 



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

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

 lations made with Ordinanj Soil Bacteria.) 



Soil, 



Amount of Ammonia in Decoction of 100 

 Cubic Centimeters (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. (Inocu- 

 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. Now 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. Rus-sell 

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



