146 
Journal of Agricultural Research 
Vol. IX, No. 5 
The percolation of 400 c. c. of water through 100 gm. of soil removed 
22.84 per cent of the ammonia from the Riverside soil and only 8.8 per 
cent from the Lordsburg soil. The percolation of the 400 c. c. of 10 per 
cent acid through the Riverside soil removed a little more than twice as 
much ammonia as the same amount of water. The leaching of the soils 
was continued until 2,400 c. c. of percolate had passed through. The 
total amount of ammonia removed by leaching with water amounted to 
only 14.2 per cent for the Lordsburg soil and 33 per cent for the River¬ 
side soil. 
The removal of ammonia by leaching with large quantities of 10 per 
cent acid was tried only with the Riverside soil, from which 2,400 c. c. 
removed 81.2 per cent of the ammonia added. 
FACTORS INFLUENCING THE FIXATION OF AMMONIA BY SOILS 
As shown in Table VI, the depth from which the soil sample is taken 
is frequently an important factor in the determination of the ammonia¬ 
fixing power of the soil. All of the semiarid soils tested, with the excep¬ 
tion of the soil from Highland, Cal., show an increased fixation with an 
increase in depth. The humid soils do not show an increased fixation 
with depth, and it would therefore seem that there may be a marked 
difference between humid and semiarid soil in this regard. However, 
the number of soils examined are too few to warrant any conclusions at 
this time. 
Table VI. —Fixation of ammonia by soils from different depths 
Depth 
of soil. 
Inches, 
o- 6 ... 
6-18 ... 
18-30 ... 
30-42 • • • 
42-54 • • • 
Ni¬ 
tro¬ 
gen in 
mo- 
niiim 
sul¬ 
phate 
®d- Lordsburg, 
ded Cal. 
per 
100 
soil. 
Mgm . 
Mgm . 
Per 
cent. 
50.00 
47.20 
94.40 
50.00 
38- 90 
77.80 
50.00 
21.80 
43 -60 
50.00 
12.90 
25.80 
50.00 
10. xo 
20.20 
Nitrogen recovered. 
Riverside, 
Cal. 
Covina, 
Cal. 
Highland, 
Cal. 
Mgm. 
Per 
cent. 
Mgm. 
Per 
cent. 
Mgm. 
Per 
cent. 
46.50 
93 *oo 
44*40 
88.80 
49 - 50 
99-00 
45 * 85 
91.70 
42*15 
84* 30 
46.95 
93.90 
40.80 
81.60 
36.05 
72.10 
47-30 
94.60 
33-85 
26. 70 
67.70 
53*40 
22.35 
44-70 
Berwyn, 
Md. 
Mgm. 
48.20 
48.70 
47.60 
47.20 
46.00 
Per 
cent. 
96.40 
97-40 
95.20 
94.40 
92.00 
Arlington, Va. 
Sample x. 
Samples. 
Mgm. 
45*40 
45-00 
46.40 
Per 
cent. 
90.80 
90.00 
92.80 
Mgm. 
45*40 
46.00 
46.40 
Per 
cent . 
90.80 
92.00 
92.80 
The addition of the same quantity of an ammonium salt in concen¬ 
trated and dilute solution shows the greatest fixation when added in con¬ 
centrated solution, as shown in Table VII. When dilute solutions were 
added, the containers were placed on a large wheel which completed 
about two revolutions per minute; thus, the soil was kept agitated dur- 
