1912 j Kelley : Biological Transformations of Nitrogen in Soils 47 



Here again it is shown that .1 gram of magnesium carbonate 

 per 100 grams of soil entirely prevented nitrification. Neither 

 do we observe any effective antagonism through the use of cal- 

 cium carbonate. 



On the one hand it was found that ammonification of dried 

 blood was seriously interfered with by the presence of small 

 amounts of magnesium carbonate, and on the other, nitrification 

 was completely prevented by its presence. In neither case was 

 there any evidence of an antagonism between magnesium and 

 calcium carbonates. In the above nitrification experiments, mag- 

 nesium carbonate not only prevented the formation of nitrates 

 but at the same time induced a reduction in the amounts of 

 nitrates originally present in the soil. It was observed that with 

 the addition of magnesium carbonate a much more abundant 

 growth of moulds took place than in the tumblers receiving cal- 

 cium carbonate. 



With a view of throwing further light on this question, total 

 nitrogen was determined, both before and after the incubation 

 period of 21 days, in a similar set of experiments to which one 

 gram of magnesium carbonate had been added. The result showed 

 that during the period of bacterial action, similar to that in the 

 preceeding nitrification experiments, the soil sustained a loss 

 equal to about 20 per cent of the combined nitrogen originally 

 present. 



Two factors suggest themselves as bearing on this question. 

 The first and probably most important is that of volatilization 

 and, therefore, loss of ammonia. J. G. Lipman'' in his numerous 

 researches found that the dilution of a heavy silt loam with 

 silica sand caused a loss of ammonia in ammonification experi- 

 ments. The loss began to manifest itself with the use of 30 per 

 cent of sand but greatly increased with larger amounts. This 

 loss was attributed to the volatilization of ammonia and was 

 sufficiently great to give an appreciable odor of ammonia above 

 the tumblers. The soils employed in the experiments herein 

 described were largely composed of sand and contained very 

 small amounts of silt and clay. The substances capable of fixing 

 large amounts of ammonia are, therefore, largely absent from 



9 N. J. Sta. Kept., 1909. 



