130 



EXPERIMENT STATION. 



[Jan. 



That sterilization of soils produces different effects on crops 

 according to the nature of the soil cannot be disputed. In this 

 exi)erinient we used two distinct types of soil, and found that 

 sterilization afl'ects both soils differently. In loams well sup- 

 plied with organic matter the effect is a stimulation from the 

 beginning on certain crops. In other soils, notably deficient in 

 organic matter (like the subsoil used in this experiment), the 

 effect may be a detrimental one. 



Lyon and Bizzell ^ have shown us that steaming reduces the 

 nitrates of the soil to nitrites and to ammonia, but most of the 

 annnonia comes from the organic nitrogen. Russell and Hutch- 

 inson - claim that the increased productiveness of sterilized soils 

 is due to an increase in the amount of ammonia present, and that 

 the excess of ammonia is the result of the increased decomposi- 

 tion of soil substances by bacteria. 



Table V. — Showing Comparison of the Amounts of Ammonia in Decoc- 

 tions of Sterilized and Unsterilized Loam. {Inoculations made with 

 Ordinary Soil Bacteria.) 



Analysis of the soil decoctions from soils similar to those used 

 in the experiments given in Table IV. show an increase of ammo- 

 nia in the sterilized loam as compared with the unsterilized. In 

 the subsoil we find just the reverse condition, the unsterilized 

 subsoil containing more ammonia than the sterilized. 



Analyses of the soil decoctions used in the experiments shown 

 in Tables II. and III. give the same results as regards the am- 

 monia content of the decoction as those enumerated above, but in 

 our experiments (Tables II. and III.) we have sterilized decoc- 

 tions of the various soils inoculated with soil bacteria. The 

 increase and decrease in the number of bacteria found in these 



' Effects of Steam Sterilization on the Soluble Matter in Soils, Lyttleton Lyon and J. A. Biz- 

 zell, Cornell Acr. Exp. Sta., Bui. No. 275. April, 1910. 



» EtTecfs of Partial Sterilization of Soil upon the Production of Plant Food, by E. J. Ru.ssell 

 and H. B. Hutchinson, Journal of Agricultural Science, Vol. HL, Part IL, October, 1909. 



