Apr. 5, 1924 
Studies with Cyanamid 
53 
Nitrification of urea was the highest at 30° C., at which temperature 74 per 
cent of the added nitrogen was found as nitrate nitrogen. Under similar condi¬ 
tions cyanamid showed 69 per cent nitrification. At this temperature cyanamid 
retarded nitrification for 20 days but later was oxidized quite rapidly. At the 
highest temperature of 38.5° C. the nitrate accumulation from urea was con¬ 
siderably less than at 30° C.; but in the case of cyanamid was exceptionally good. 
The maximum nitrate accumulation for the entire experiment, which was 79.6 
per cent, was obtained at this temperature. Under the same conditions urea 
gave 36.7 per cent. 
Table VII.— Nitrate formation from cyanamid and urea in soils maintained at 
different temperatures 
-9 TO 18° c. 
Soil 
Urea 10 mgm. N 
per 100 gm. soil— 
Cyanamid 10 mgm. 
N per 100 gm. soil— 
Incubation period 
alone 
nitrates 
mgm. N 
Nitrates 
mgm. N 
Recovery 
of N as 
nitrates 
mgm. N 
Nitrates 
mgm. N 
Recovery 
of N as 
nitrates 
mgm. N 
Days 
11_______ 
0.69 
0.95 
0. 26 
0.37 
-0.32 
20_ 
1.36 
2.06 
.70 
.50 
-.86 
30_____ 
1.56 
2.40 
.84 
.54 
-1.02 
42_ 
2.37 
3.38 
1.01 
.73 
-1.64 
15 TO 20° C. 
11_ 
20_ 
30_ 
42_ 
1.84 
4.17 
5. 21 
7.44 
2.72 
6.65 
10.08 
11.16 
0.88 
2.48 
4.87 
3. 72 
0. 55 
1. 79 
3.91 
5.95 
-1.29 
-2.38 
-1.30 
-1. 49 
30° 
C. 
11___ 
3.29 
4.82 
1.53 
1.10 
-2.19 
20_ 
7.27 
12.02 
4. 75 
5.89 
-1. 38 
30__ 
8.45 
14.88 
6.43 
12.50 
4.05 
42_ 
10.42 
17.86 
7.44 
17.36 
6.94 
38.5° C. 
2.50 
4.73 
2.23 
1. 72 
6.42 
9.67 
3.25 
11. 57 
10.08 
13.89 
3.81 
16.89 
11. 57 
15.24 
3. 67 
19. 53 
These experiments are of too limited a nature to justify broad conclusions but 
certainly indicate that there is little justification for the statement that hot 
weather is unfavorable for the use of cyanamid while cool weather favors the 
desirable transformations. Just the reverse was the case in the experiment here 
reported and the indications are that low temperatures slow up the desirable 
changes and favor the formation of dicyanodiamid and possibly guanylurea. 
NITRIFICATION OF CYANAMID AND UREA IN PARTIALLY STERILIZED SOILS 
In order to determine the effect of partial sterilization of a soil upon nitrifi¬ 
cation, varying percentages of phenol were added to 100 gm. samples of soil 
containing 10 mgm. of nitrogen as cyanamid or urea. The percentages of phenol 
