Apr. 5, 1924 
Studies with Oyanamid 
65 
Table XIV.— Comparison of the rates of nitrification of guanidin nitrate, nitro 
guanidin, biguanid nitrate and urea 
Treatment 
Mgm. 
N 
added 
other 
than 
nitrates 
14 days 
29 days 
50 days 
71 days 
Ni¬ 
trates 
mgm. 
N 
In¬ 
crease 
over 
control 
mgm. 
Ni¬ 
trates 
mgm. 
N 
In¬ 
crease 
over 
control 
mgm. 
Ni¬ 
trates 
mgm. 
N 
In. 
crease 
over 
control 
mgm. 
Ni¬ 
trates 
mgm. 
N 
In¬ 
crease 
over 
control 
mgm. 
Soil alone.. 
0 
3.85 
5.00 
6.94 
7.91 
Urea... 
10 
4.93 
1.08 
10.78 
5.78 
14.20 
7.26 
17.36 
9.45 
Guanidin nitrate.. 
10 
5.65 
-.60 
8. 33 
.52 
11.61 
1.62 
12.50 
3.31 
Sodium nitrate®... 
0 
6.25 
7.81 
9.99 
9.19 
Nitro guanidin. 
10 
4.71 
.86 
6.10 
i. io 
8.68 
1.74 
8.80 
.89 
Biguanid nitrate_ 
10 
4.98 
-.32 
7.14 
-.21 
9.19 
.97 
8.91 
.90 
Sodium nitrate &... 
0 
5.30 
7.35 
8.22 
8.01 
a The application of sodium nitrate was equivalent to the nitrate present in the guanidin nitrate 
treatment. 
& The application of sodium nitrate was equivalent to the nitrate present in the biguanid nitrate treat¬ 
ment. 
It will be observed that guanidin nitrate slightly inhibited nitrification 
during the first two weeks but later there was a gradual increase in nitrate 
nitrogen until at the end of the experiment (71 days) 33 per cent of the guanidin 
nitrogen had been converted into the nitrate form. The behavior of this com¬ 
pound was, therefore, quite similar to that already noted in the case of guanylurea 
sulphate. Nitro guanidin did not have an injurious effect on nitrate formation 
but nevertheless it did not nitrify to any marked extent. The maximum nitri¬ 
fication which occurred at the end of 50 days was 17.4 per cent. Since one- 
fourth of the nitrogen present in nitro guanidin is in the nitrite form it is possible 
that the nitrate formation was wholly from the nitrite radical. 
Biguanid nitrate produced a very slight decrease in nitrates during the first 
month but the decrease was practically within experimental error. At the end 
of 50 days 9.7 per cent of the added biguanid nitrogen was recovered as nitrates 
and this percentage was not increased by longer incubation. 
Urea, which was included for comparison, nitrified gradually until at the end 
of the experiment the maximum nitrification of 94.5 per cent was reached. 
NITRIFICATION OF GUANIDIN CARBONATE AND AMMONIUM SULPHATE 
Subsequent to starting the experiment discussed above a sample of guanidin 
carbonate was obtained and a new series of experiments started similar to the 
first using this material in comparison with ammonium sulphate. Three rates 
of application were used namely, 5, 10 and 20 mgm. N per 100 gm. soil. The 
figures given in Table XV are the average of duplicate determinations obtained 
by the colorimetric method. These results are also shown in figure 12. 
Table XV.— Comparison of the rates of nitrification of guanidin carbonate and 
ammonium sulphate 
Treatment 
I 
Mgm. 
N 
added 
19 days 
35 days 
56 days 
75 days 
Ni¬ 
trates 
mgm. 
N 
In¬ 
crease 
over | 
control 
mgm. 
Ni¬ 
trates 
mgm. 
N 
In¬ 
crease 
over 
control 
mgm. 
Ni¬ 
trates 
mgm. 
N 
In¬ 
crease 
over 
control 
mgm. 
Ni¬ 
trates 
mgm. 
N 
In¬ 
crease 
over 
control 
mgm. 
Soil alone.... 
0 
6.86 
7.66 
8.99 
8.54 
Ammonium sulphate. 
5 
10.21 
3.35 
11.58 
3.92 
14 48 
5.49 
13.72 
5.18 
Do. 
10 
10.00 
3.14 
16.95 
9.29 
18.95 
9.96 
18.95 
10.41 
Do.. 
20 
9.44 
2.58 
26.39 
18.73 
28.18 
19.19 
27.79 
19.25 
Guanidin carbonate. 
5 
4.68 
-2.18 
10.22 
2.56 
12.57 
3.58 
12.71 
4.17 
Do.. 
10 
2.07 
-4.79 
9.31 
1.65 
15.43 
6.44 
17.66 
9.12 
Do. 
20 
1.38 
-5.48 
1.71 
-5.95 
9.74 
.75 
18.28 
9.74 
