220 
Journal of Agricultural Research 
Vol. IX, No. 7 
and second irrigation was presumably due to the nitrification of the barn¬ 
yard manure, which was applied several weeks before the first irrigation. 
It was observed that the concentration of nitric nitrogen in the surface 6 
inches of soil 18 inches from the furrow was comparatively small, consider¬ 
ing the amount of nitric nitrogen in the soil. In this soil the highest nitrate 
content amounted to 6.55 mgm., which is but little higher than the high¬ 
est amount secured in plot B, which received no nitrogenous fertilizers 
and in which the nitrate content as a whole was much lower. Notwith¬ 
standing the comparatively weak lateral movement in the surface 6 
inches, the concentration of nitrates 18 inches from the lower depth was 
quite marked, causing a very uneven distribution of the nitrates within 
reach of the feeding roots. 
°Q< 
52? 
3 
/Sr 4ZW /«** 2*0. 3*0. /&r 
A/o. O/r //?/?/e?s*770A/ 
Fig. 6.—Diagram showing the distribution of nitrates in plot F before and after irrigations. Season of 1916. 
Plot G shows an accumulation of nitric nitrogen 18 inches from the 
furrows after the second irrigation, amounting to 29.65 mgm., while the 
supply 9 inches from the furrow at this time amounted to only 2.56 mgm. 
At the lower depths the nitrate content is much smaller, and the varia¬ 
tion is less marked. However, there is a tendency for the nitrates to 
move toward the point farther from the furrows, even at a depth of 30 
to 42 inches (fig. 7). 
At the beginning of the irrigation season the soil of plot H showed a 
high nitrate content in the upper layers, which amounted to 6.22 mgm. 
in the upper 6 inches and 3.63 mgm, at a depth of 6 to 18 inches. Before 
the first irrigation the nitric nitrogen in the upper 6 inches was found to 
be nearly the same at 9 and 18 inches from the furrow. After the third 
irrigation the variation was from 2.14 to 42 mgm. The distribution 
