1912] Kelley: Biological Transformations of Nitrogen in Soils 41 



sium or ammonmm carbonates. It is but fair to mention in this 

 connection, however, that great dilution of these carbonates was 

 employed. 



In 1910 Dr. J. G. Lipman** observed that the addition of one 

 gram of calcium carbonate per one hundred grams of a New Jer- 

 sey soil stimulated the ammonification of dried blood but de- 

 pressed the formation of ammonia from cotton seed meal. In 

 parallel experiments he observed that an equal amount of mag- 

 nesium carbonate caused a depression in the ammonification of 

 dried blood but stimulated the ammonification of cotton seed 

 meal. In other words, the ammonification of dried blood and cot- 

 ton seed meal in one and the same soil were affected by calcium 

 and magnesium carbonates in opposite ways, both as regards the 

 carbonates and the nitrogenous substances employed. These re- 

 sults are interesting and suggestive and point to the complexity 

 of this single step in the preparation of available nitrogen from 

 the organic substances occurring in soils. 



In the same year Kellerman and Robinson^ pointed out that 

 the addition of magnesium carbonate to a highly magnesian soil 

 in quantities above 0.25 per cent greatly depressed the formation 

 of nitrates while the application of calcium carbonate in quanti- 

 ties up to 2 per cent markedly stimulated nitrification. The 

 growth of crops on this soil had been found to be much more 

 favorably influenced by the application of ground oyster shells 

 than by magnesium limestone. The authors inferred from their 

 experiments that the inferior effects on crops following the appli- 

 cation of dolomitic limestone may be due, in part, to retarded 

 nitrification. 



AMMONIFICATION 



In the course of some studies on soil bacteriology at the Uni- 

 versity of California, the writer undertook a study of certain 

 biological transformations, as affected in two different sandy soils 

 from California by varying amounts and combinations of calcium 

 and magnesium carbonates. On account of the striking nature 

 of the results obtained in the preliminary ammonification ex- 



'■■ N. J. Sta. Eept., 1910. 

 7 Science, 32, p. 159. 



