Steam Sterilization on Water-Soluble Matter in Soils. 251 



Immediate effect of heat on certain constituents of these soils 



Table I presents the results of these analyses of Soils Nos. 5, 6, and 

 7 when unheated and immediately after heating. Soil No. 7 both 

 leached and unleached was steamed for two hours at two atmospheres 

 pressure. Soils Nos. 5 and 6 were steamed for four hours at two at- 

 mospheres. wSoil No. 7 was leached where so indicated with four parts 

 of water before being analyzed or steamed. 



Table I. — Showing Immediate Effect of Steam Under Pressure upon 



Certain Soils 



It may be seen from Table I that the total water-soluble matter was 

 greatly increased in every soil by heating. The relative increase was 

 greater for the two soils (Nos. 5 and 6) that were steamed for four hours. 

 The leached sample of soil No. 7 contained only about one-half as much 

 total soluble matter when unsteamed as did the unleacned sample of 

 the same soil, but the leaching did not decrease the total soluble matter 

 in the steamed soil. 



Soil No. 6 is a much more productive soil than is No. 5, although it 

 contains less organic matter. The effect of the steaming has been to 

 increase more largely the total soluble matter in Soil 5 by decomposing 

 the organic matter that under natural conditions decomposed very 

 slowly. This is shown by the columns showing the actual and relative 

 quantities of soluble inorganic matter. While the rate of solubility of 

 the unsteamed vSoils Nos. 5 and 6 is in the order of their productiveness, 

 the solubility of these soils steamed is in the reverse order. The much 

 larger proportion of organic matter in the total soluble matter, in the 

 extract of the steamed soils than in the unsteamed, is noticeable in all 

 of the soils. 



