50 
Journal of Agricultural Research 
Vol. XXVIII, No. 1 
during the cool months of the year since a hot summer, which is usually accom¬ 
panied by a drought, favors the formation of dicyanodiamid rather than nitrates. 
In order to secure more accurate data upon these points the two experiments which 
follow were made. 
The methods were the same as previously given except that only 100-gm. 
samples of soil were used. Urea was selected as the standard for comparison 
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Fig. 4—Diagram showing the rate of nitrification of cyanamid and urea in presence of different percentages 
of moisture 
instead of ammonium sulphate. The soils were kept at room temperature during 
the incubation period. The data obtained by the colorimetric method, are given 
in Table VI and figure 4. 
It will be noted that the per cent nitrification of cyanamid in the soil con¬ 
taining 10 per cent moisture is as high as that of urea under similar conditions 
