Apr. 30, 1917 
Fixation of Ammonia in Soils 
147 
ing the fixation period. However, it is observed that the nitrogen 
recovered varied from 52 to 53.5 per cent when 20 c. c. of solution were 
added and from 65 to 66 per cent when 720 c. c. of solution were added. 
Table; VII .—Fixation of ammonia from concentrated and dilute solutions 
Quantity of solution 
added. 
Nitrogen 
added per 
100 gm. of 
soil. 
Nitrogen recovered 
from ammonium 
sulphate. 
Nitrogen recovered 
from ammonium 
chlorid. 
Nitrogen recovered 
from ammonium 
nitrate. 
C. c. 
20 . 
200. 
360.. 
720. 
Mgm. 
50. OO 
50. CO 
50. OO 
50. OO 
Mgm. 
26. 10 
27. 52 
28. 25 
32. 61 
Per cent. 
52. 20 
55 - °4 
5 6 - 5 ° 
65. 22 
Mgm. 
26. 2? 
28. 10 
29. OO 
32. 60 
Per cent. 
53 - 50 
56. 20 
58. 00 
65. 20 
Mgm. 
26. OO 
27. 80 
28. 80 
33- 00 
Per cent. 
52. OO 
55 - 60 
57. 60 
66. 00 
If the fixation is dependent upon the chemical reactions, it would 
seem that the temperature would be an important factor in determining 
the amount of ammonia fixed. Table VIII shows the results secured 
with two soils when held at temperatures ranging from 5 0 to ioo° C. In 
both soils the amount of ammonia recovered decreased as the tempera¬ 
ture increased. In the Lordsburg soil the ammonia recovered when 
the soil was held at ioo° is only 53.6 per cent of the amount recovered 
when the soil was held at 5 0 . 
Table VIII .—Effect of temperature on the fixation of ammonia by soils 
Temperature. 
Nitrogen 
in am¬ 
monium 
sulphate 
added per 
100 gm. 
of soil. 
Ni rogen recovered. 
Riverside soil. 
Lordsburg soil. 
°C. 
Mgm. 
Mgm. 
Per cent. 
Mgm. 
Per cent. 
5 ... 
50. OO 
27. 42 
55 - 44 
12. 50 
25.00 
50.00 
25.48 
5 °. 96 
10. 10 
20. 20 
50 . 
50. OO 
20. l6 
40. 32 
9. 10 
l8. 20 
75 .. 
50. 00 
I9.32 
38. 64 
8. 80 
17. 60 
50.00 
! 7 - 3 6 
34 * 72 
6. 70 
13. 40 
The time of standing exerted some influence, as can be seen by re¬ 
ferring to Table IX. As might be expected, the most rapid fixation 
takes place during the first few minutes after the ammonia is added; but 
the process is apparently not complete even after a period of 72 hours, 
as less ammonia was removed after 96 hours than after 72 hours; and in 
the Lordsburg soil the difference is quite appreciable. 
