224 
Journal of Agricultural Research 
Vol. IX, No. 7 
gation. With this small nitrate content it would seem scarcely possible 
to secure high concentrations at any point as a result of the irrigation. 
However, after the second irrigation the nitric nitrogen in the surface 
6 inches of soil 18 inches from the furrow amounted to 4.07 mgm., while 
9 inches from the furrows it amounted to only 0.5 mgm. The nitrate 
supply below 6 inches is very low, and little or no movement can be 
traced to the irrigation (fig. 10). 
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Fig. 10.—Diagram showing the distribution of nitrates in plot M before and after irrigations. Season of 1916. 
The nitric nitrogen in the soil from plot O was low at the beginning 
of the irrigation season. The upper 6 inches showed a supply of only 
0.65 mgm., while the amount of the lower depths was considerably less. 
Between the first and second irrigations there is a rather marked increase 
in the nitrate content of the upper 6 inches. This increase, like that in 
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Fig. 11.—Diagram showing the distribution of nitrates in plot O before and after irrigations. Season of 1916. 
plot F, is presumably due to the nitrification of the manure which was 
applied during the early spring. The maximum amount of nitric nitro¬ 
gen found in the upper 6 inches of this soil was 5.25 mgm., which indicates 
a very weak lateral movement. There was apparently some tendency for 
the nitrates to move away from the furrows in the deeper layers, but the 
distribution was apparently much more uniform than in the other manure 
plot, which was a much lighter soil (fig. 11). 
