128 



Partial Sterilisation of Soil 



significance they show that the tohiened soil loses a little more humus 

 than the untreated, but gains a little more humic nitrogen. It is, how- 

 ever, quite certain that the toluened soil has not lost any humic 

 nitrogen, and the increased ammonia and nitrate recorded in Table 2 

 cannot have come from humic nitrogen. 



The heated soil behaves rather differently from the others, but we 

 have obtained a good deal of evidence to show that heat decomposes 

 humus, and brings about a loss of humic nitrogen. 



The distribution of nitrogen compounds in a typical case is as 

 follows : 



Table 6. 



* The " unstable compounds" merge into " other compounds," and the division line is 

 purely arbitrary, 



§ 20. Ahsorjition of oxygen. This was investigated by the method 

 devised by one of us and described elsewhere ^ The relative amounts 

 absorbed in 10 days by the various soils are given below and show that 

 the toluened and heated soils absorb during the first month more than 

 does the untreated soil. This result has been previously obtained and 

 appears to be quite general. After a time, however, the rate of absorption 

 begins to fall off and at the end of 72 days both the toluened and the 

 heated soils are absorbing less than the untreated soil. 



' E. J, Russell, this Journal, 1905, Vol. i. p. 261. 



