268 



BULLETIX 275. 



breaking down of soluble organic matter has not proceeded normally 

 in the steamed soils or that the effect of plant roots has been to make 

 soluble more organic matter. However, as there has been little in- 

 crease in the total soluble matter in the soil to which the infusion was 

 added, the former alternative probably holds. This hypothesis is also 

 substantiated by the depressed nitrification in the uncropped steamed 

 soils as compared with the uncropped soil not steamed. 



Fig. 77 — Wheat planted four mouths after soils were steamed. It shows the same 

 relative growth as when planted a few days after steaming 



Vessel jj — Soil No. i unsteamed 

 Vessel ^y — Soil No. 2 unsteamed 

 Vessel 61 — Soil No. i steamed 

 Vessel 6 J — Soil A'o. 2 steamed 



Nitrification has apparently not proceeded materially better in 

 the soil to which the infusion was added than in the one not so treated. 

 Water-soluble total nitrogen is noticeably less in the infusion-treated 

 soil, while water-soluble ammonia is practically the same in both soils. 

 This indicates that inoculation has served to increase the conversion 

 of organic nitrogen into ammonia. The rapid breaking down of organic 

 substances immediately following the application of the infusion would 

 doubtless account for the better germination and early growth in that 



