1912. 



PUBLIC DOCUMENT — No. 31. 



129 



as compared with the number in the unsterilized loam decoction ; 

 thus the experiments with loam soil in Table III. bear out the 

 results recorded in Table 11. , where the same kind of loam soil 

 was used in the decoctions. When a sterilized and unsterilized 

 subsoil were used in the decoctions we found tfiat a greater num- 

 ber of bacteria were present in the unsterilized decoction. This 

 fact proves that the sterilizing of this particular soil resulted in 

 adverse conditions for bacterial increase. 



At this point it might be of interest to insert a table taken 

 from a previous report of the Hatch Experiment Station/ show- 

 ing the growth of soy bean in sterilized and unsterilized loam and 

 subsoil. A glance at this will show that the greatest gain in 

 plant growth was made in the loam soil, and the least in the sub- 

 soil. These results coincide with the relative growth of bacteria 

 in the two soils, as shown in Table III. 



Table IV. — Showing Growth of Soy Bean in Sterilized and Unsterilized 

 Loam and Subsoil (from Hatch Experiment Station Annual Report, 

 1906). 



Glancing over this table one can readily see that there is a 

 connection between the development of bacteria and the growth 

 of soy beans in sterilized and unsterilized soils. The soy beans 

 showed an increase of growth in the sterilized loam over that 

 given in the unsterilized loam. In the subsoil the unsterilized 

 soil produced a greater growth than the sterilized. The same 

 held true in regard to the development of bacteria. Decoctions 

 of the sterilized loam produced about twenty times the number of 

 bacteria as the unsterilized. In the sterilized subsoil there is a 

 decrease in numbers as compared with the unsterilized, or in 

 other words, the unsterilized subsoil produced twice as many 

 bacteria as the sterilized. 



' Comparison of Sterilized Loam and Subsoil, by G. E. Stone, 18th Ann. Rept. of the Hatch 

 Exp. Sta., pp. 125, 126, 1906. 



