1914] Lipman-Burgess: Ammonificatio7i and Nitrification in Soils 133 



for four weeks at 27° C to 30° C. Other explanatory data are 



given in Table 2, which shows the results obtained from the 

 nitrate determinations made as above explained. 



It is quite clear from the foregoing table that all of the salts 

 used exercise marked effects on the nitrifying flora of the soil 

 employed. For the reason that some pronounced differences 

 obtain between the action of the different salts we shall discuss 

 each of them separately at first. 



CuSO, 



It can be seen at a glance that the data in Table 2 show 

 copper to be the most stimulating of the salts employed so far 

 as a soil-nitrifying flora is concerned. While, unfortunately, 

 the duplicate determinations for the lowest concentration do not 

 agree well, they indicate clearly that in those quantities (0.0125 

 per cent, or 125 parts per million) copper has either no effect 

 on the nitrifying flora or a slightly depressing one. By doubling 

 the concentration of the copper salt we obtain a slightly stimu- 

 lating effect, but by doubling the latter concentration we obtain 



