Oct. 8, 1917 
Nitrate-Nitrogen Accumulation in Soil 
61 
They also found very slight differences in the composition of air drawn 
from depths of 6 inches and 18 inches 
Djarenko (3), investigating the effect of different methods of fallowing 
practiced in Russia upon the composition of the soil atmosphere, secured 
the results given below. He analyzed the soil gases 14 times between 
April 20 and September 1. 
Black fallow. 
April fallow. 
June fallow. 
Peasant fallow. 
Min. 
Max. 
Ave. 
Min. 
Max. 
Ave. 
Min. 
Max. 
Ave. 
Min. 
Max. 
Ave. 
Oxygen.per cent.. 
17.1 
20- 7 
18.9 
19.2 
21*5 
19-9 
18.2 
20.0 
19.4 
10.6 
19 - 1 
is -5 
Air per liter of soil.. ; . c. c.. 
290 
410 
3 32 
240 
420 
348 
200 
33 o 
264 
iso 
280 
208 
Oxygen per liter of soil. c. c,. 
50 
81. s 
64-5 
48 
84 
67.8 
36-5 
65-9 
Si -3 
z6 
48 
32.7 
Black fallow is worked in autumn and again the following April and 
June. April fallow is worked in April and June. June fallow is first 
worked in June. Cattle are allowed to roam upon peasant fallow in the 
spring, thus giving it a much-trodden effect. It is first cultivated in 
June. All are seeded on August 1. 
Jodidi and Wells (4), analyzing soil gases from 22 plots at the Iowa 
Station daily from April to August, inclusive, found the lowest, highest, 
and average monthly analyses to be 0.04, 0.82, and 0.25 per cent for 
carbon dioxid and 19.36, 21.20, and 20.5 per cent, respectively, for 
oxygen. The 5-month average of individual plots varied from 0.18 to 
0.44 per cent for carbon dioxid and 20.18 to 20.62 per cent for oxygen. 
Samples were drawn from 7 inches below the surface. 
Leather (8), in his work upon soil gases at Pusa, India, used very 
different methods of analysis, which render it difficult to compare his 
results with those given above. From a definite volume of soil all gases 
that could be extracted with a Topler pump were removed for analysis. 
Thus, not only the air existing in free pore space but also much that 
was held in solution was removed. Owing to the much greater solu¬ 
bility of carbon dioxid than oxygen and nitrogen in water, the percent¬ 
age present in dissolved air is much higher and as a result the percent¬ 
age in air extracted from the soil by this method is much higher. 
Sufficient data are not given for making the necessary corrections in 
order to place the figures upon the same basis as those already given. 
By assuming, though, that the five instances in which such corrections 
are made by the author are representative, the carbon dioxid figures 
reported below are approximately five times too high, while the oxygen 
figures should be increased by approximately 15 per cent. According to 
Leather (8, p. 106)— 
When the total carbon dioxide is much less than 10 per cent and the soil is not par¬ 
ticularly dry, it is nearly all in solution. 
