252 Bulletin 275. 



Nitrogen in the form of soluble organic matter or ammonia is greatly 

 increased in all soils by steaming. By subtracting the figures for water- 

 soluble ammonia from those just mentioned, the difference shows the 

 nitrogen in soluble organic matter. By doing this it will be seen that the 

 larger part of the water-soluble nitrogen is in the form of organic matter. 

 The very large increase in these two forms of nitrogen on steaming is 

 very marked. 



In the nitrate column is seen one of the most interesting results of the 

 operation, viz., the loss of nitrates, doubtless due to reduction to nitrites 

 and ammonia. This accounts only in a measure for the large formation 

 of ammonia, most of which must have been formed from organic nitrogen. 



Nitrites were produced in moderate quantities when the nitrates were 

 very high in the unsteamed soil, but not when the nitrates were low. 

 Whether the process of leaching occasioned the larger amount of nitrites 

 in the unsteamed soil is a question raised by these figures. 



The ammonia in the freshly steamed soil is in large part soluble in 

 water, but it will be seen from the column containing the quantities of 

 ammonia soluble in dilute hydrochloric acid that at least a portion is 

 not soluble in water. As will be shown later, there is a gradual disap- 

 pearance of most of the water-soluble material on standing, and as am- 

 monia is quickly absorbed by soils this water-insoluble ammonia may 

 have been converted from the water-soluble condition during the short pe- 

 riod intervening between steaming and analyzing. This is indicated by 

 the fact that the original soils contained no ammonia determinable by 

 the method of analysis used. 



In leached Soil No. 7 determinations were made of water-soluble PO4. 

 While only a trace existed in the original soil the steamed soil contained 

 94 p. p.m. 



Changes occurring in steamed soils on standing 



Both the steamed and the unsteamed soils were allowed to stand in the 

 greenhouse in pots without being planted to any crop, the surface being 

 covered with filter paper, and by the addition of distilled water the 

 moisture content was maintained at about twenty-five percent of dry 

 soil. No special precaution was taken to prevent inoculation except from 

 other soils. The number of bacteria in the sterilized soil increased to 

 an enormous number in the course of several months, but as there was 

 practically no increase in nitrates it is evident that either nitrifying 

 bacteria did not enter the soil or that their growth was inhibited. In 

 this respect our experiments confirm those of Deherain. 



Table II shows the changes that occur in some of these soils on stand- 

 ing, analyses having been made at 56, 82 and 90 days after heating. 



