320 
Journal of Agricultural Research 
Vol. IX, No. 9 
Here we find a much smaller quantity of nitric nitrogen in all the 
plots during the summer than during either spring or fall; and with one 
exception, the alfalfa, it is lower in the fall than in the spring. During 
the summer months we find the alfalfa and oats much closer feeders on 
the nitric nitrogen of the soil than are the other plants. However, the 
average quantity of nitric nitrogen found in the 6 feet of soil for the 
season on the alfalfa, oat, and com soil is nearly the same in each case. 
This appears to contradict the conclusions previously reached by us; 
but it must be borne in mind that in the previous work our samples 
were taken to a depth of io feet, and a comparison of the two sets of 
results indicates that the alfalfa and oats, besides being closer feeders 
upon nitric nitrogen, feed to a greater depth than do the other crops. 
Furthermore, it makes it very certain that in a study of the nitric nitro¬ 
gen of a soil, such as used in these experiments, samples must be taken 
to a great depth; otherwise erroneous conclusions will be drawn from 
the results obtained. 
It is interesting to note that throughout the season there is over twice 
the nitric nitrogen in the potato and fallow soil than in any of the other 
soils, and even these plots show a decrease in nitric nitrogen during 
summer and fall. There is a slight difference in favor of the fallow plots 
in the fall, but in the spring the quantity in both sets is the same. 
COMPOSITION OP THE SOIL SOLUTION 
Moisture determinations were made on each soil at time of sampling 
so the results could be calculated to a dry basis. From the results 
obtained for nitric nitrogen and soil moisture, it is possible to calculate 
the concentration of the soil solution. While this has been done for each 
individual plot, only the summarized results are reported in Tables XX 
and XXI, and they represent the average for all the determinations 
covering these years. 
Table XX .—Concentration of the soil solution growing various crops 
[Results reported as nitric nitrogen parts per million of soil solution] 
Crop. 
First 
foot. 
Second 
foot. 
Third 
loot. 
Fourth 
foot. 
Fifth 
foot. 
Sixth 
foot. 
Average. 
Alfalfa. 
16. O 
IO. 8 
9.8 
5*2 
6. 7 
4 - 7 
8. 87 
Oats. 
14. 0 
7.6 
8.7 
6.8 
7.0 
6.4 
8. 92 
Com. 
13-3 
7*7 
7*5 
6.2 
6.9 
6.6 
8.03 
Potatoes. 
32. 6 
21. 6 
22.3 
24. 0 
24. 1 
15.2 
23. 28 
Fallow.. 
26 . 4 
25*3 
23*5 
18.7 
20. 6 
T 9 * 7 
22.38 
It is interesting to note the great difference between the concentration 
of the soil solution of the alfalfa and potato soils. The average concen¬ 
tration of the alfalfa, oat, and com land is about the same, while the 
potato and fallow is the same. However, there is a slight difference in 
