March 26, 1909] 



SCIENCE 



507 



nitrifying soils was afforded in 1903 during 

 an attempt of one of us to demonstrate nitri- 

 fication to a class in bacteriology after the 

 usual laboratory manner." The attempt re- 

 sulted in a complete failure to secure 

 nitrification. This observation was con- 

 firmed by the other at a later time while 

 working independently with other soils. This 

 ifi noted on page 14 of the report of the North 

 Carolina Agricultural Experiment Station, 

 1906-7. Since that time, in connection with 

 our studies in nitrification, many samples of 

 soils have been tested for nitrifying power 

 with the result that a large majority of the 

 soils of this region are found to be devoid of 

 this power. The numbers of the soils tested, 

 dates, mode of test, whether in soil or in solu- 

 tion, and the results, are given in the follow- 

 ing table. 



The tests in solutions were made by the 

 usual method of placing from 0.2 g. (Ashby's 

 Method) to 5 or 10 g. of the soil to be tested 

 into an ammoniacal solution such as that of 

 Omelianski, Wiley or Ashby. 



Tests in soil were made by adding nitrogen- 

 ous material, organic or ammoniacal, to the 

 live soil or by sterilizing the soil, adding the 

 nitrogen, then inoculating with a suspension 

 of the soil to be tested, incubating, shaking 

 with water, filtering, clarifying and analyzing. 



Soils which are reported here as negative 

 did not give enough nitrate or nitrite to re- 

 spond to the diphenylamine test. 



SAMPIiES OF LOCAi SOILS 



29 per cent, nitriflers. 

 71 per cent, non-nitrifiers. 



LOCAL SOILS 



37 per cent, nitriflers. 

 63 per cent, non-nitrifiers. 



It is seen that of the 62 local samples tested 

 in soil culture, 44, or 71 per cent., failed to 

 nitrify, 18, or only 29 per cent., nitrified ; of the 

 40 different local soils tested 15, or 37 per cent., 

 nitrified while 25, or 63 per cent., failed to 

 nitrify, even though soils which sometimes 

 nitrified slightly and sometimes failed, as 

 Nos. 1783 and 1746, are recorded for this 

 purpose as nitrifying soils. 



^ Buxton, B. H., Jour. Ap. Mic, 5, p. 1975. 



' Tested at least twelve times and never failed 

 to nitrify but once. 



