Oct. 8, 1917 
Nitrate-Nitrogen Accumulation in Soil 
47 
tion could not be due to the depth of column. Also, if access of oxygen 
were influencing nitrification these samples should have shown greater 
nitrate accumulation in upper layers.) (3) The lower-lying strata of all 
samples show higher nitrate gains than do the upper layers. 
Tabi<3 II .—Effect of variation in depth of column and compactness of soil upon nitrate 
accumulation 
[Results are expressed as gain or loss in milligrams of NO3 per 100 gm. of soil] 
Sample 
No-a 
Ratio, 
diameter 
to depth. 
Depth of 
column. 
Sample from 
depth of— 
Incubation. 
10 days. 
20 days. 
30 days. 
Loose. 
Com¬ 
pact. 
Loose. 
Com¬ 
pact. 
Loose. 
Com¬ 
pact. 
Inches . 
Inches . 
I . 
! 14:1 
0.4 
0-4 
0.05 
O. 60 
4 * 50 
12. 60 
2 . 
7 * 5 :1 
I. 25 
O-I.25 
— 2. 00 
2. 90 
6. 20 
10. 20 
12. 70 
26. OO 
3A . 
3 * 5 :i 
2. 5 
O-I.25 
— . 22 
8. 60 
7 * 30 
28. 80 
26. 80 
36. OO 
3B. 
3 * 5 :i 
2 * 5 
I. 25-2. 5 
• 59 
5 * 70 
7. IO 
28. 20 
27. 40 
35 * 50 
4A . 
i* 75 : 1 
5 *° 
0-1 
4. 60 
4 * 5 ° 
31. 60 
32 . 50 
35- 60 
41. 40 
4 B . 
i* 75 : 1 
5 *o 
2-3 
6. 62 
6. 40 
3 i* 50 
41. 50 
44.90 
51. 80 
4C. 
i* 75 :i 
5 *o 
4-5 
7. 08 
4*40 
32. 60 
44. 60 
47 . OO 
55 * 90 
rA. 
i:2. K 
18.0 
0-2 
— . 20 
. 30 
cB. 
i:2* < 
18. 0 
8-10 
3. 80 
0 
40 
. 
cC. 
18. 0 
16-18 
O 
2 . AO 
10. 80 
6 A. 
1:9 
24. 0 
0-2 
. 70 
- 4*30 
- .40 
4. 70 
6B. 
1:9 
24. 0 
7-9 
— . 20 
- • 5 o 
3.80 
3 * 50 
6 C 
x: 0 
24 . O 
10—12 
1. 80 
1. 80 
6D. 
1:0 
24 . O 
14—16 
- .80 
. 20 
10.80 
23. 40 
6E. 
x * 7 
HO 
24 . O 
nr v 
18—20 
— . 60 
. 60 
10.70 
0 — 
26. 70 
6 F. 
1:9 
t - * 
24. O 
22-24 
1. 20 
2. 30 
20. 20 
23. 40 
a A, B, C, etc. are different layers of same column. 
The data reported in Table III were secured from samples containing 
50 mgm. of nitrogen as ammonium sulphate and 0.5 gm. of calcium 
carbonate per 100 gm. of soil. They were incubated at room tempera¬ 
ture for three weeks. Water lost by evaporation was replaced from time 
to time. Soil was incubated in 500-c. c. wide-mouthed bottles. The 
water content varied as indicated in Table III. The samples marked 
“loose” were as in previous experiments. Those marked “medium” 
were tamped to two-thirds the “loose” volume. Those marked “com¬ 
pact” were packed to four-sevenths the original volume. It was difficult 
to reduce further the volume of this soil. In some of the following ex¬ 
periments it was possible by continuous pounding to reduce some sam¬ 
ples to one-half the “loose” volume, but this was exceedingly difficult 
either with high or low moisture contents. With low-water contents such 
tightly packed samples would burst the heavy glass cylinders upon slight 
change in temperature. The above phenomenon, together with the fact 
that an unprotected column of such packed soil 6 inches long would sup¬ 
port considerable stress applied at right angle to the length without 
breaking, gives some idea of how tightly the soil in this and succeeding 
experiments was packed. 
