May 14, 1917 
Soil Nitrogen and Nutrition of Citrus Plants 
217 
irrigation the nitrates 9 inches from the furrow have been reduced to 
about 2.5 mgm., while the soil 18 inches from the furrows has increased 
to 10 mgm. A lateral movement has also taken place at a depth of 6 to 
18 inches. The results obtained below a depth of 18 inches for the first 
irrigation are somewhat erratic. Samples drawn before the second irri¬ 
gation indicate a more even distribution of nitric nitrogen than did the 
samples drawn after the first irrigation. In the upper 6 inches the fre¬ 
quent cultivation between irrigations is, no doubt, a factor in bringing 
about a more even distribution of nitrates. However, it is seen that there 
is apparently a more even distribution of nitric nitrogen below the cul¬ 
tivated zone before each irrigation than after the previous irrigation. 
It does not seem possible that the greater uniformity in distribution 
before irrigations can be due to diffusion, as the moisture in soils, when 
not water-soaked, is quite different from that existing in the case of 
liquids confined in a vessel. The soil moisture being distributed in 
discontinuous phases would seem to make the force of diffusion of 
little consequence in bringing about a more even distribution of the ni¬ 
trates concentrated in zones by the lateral movement of the irrigation 
water. It is believed that the apparently more even distribution before 
an irrigation than after the last irrigation may be explained in a large 
measure by the lack of uniformity in the distribution of furrows from 
one irrigation to another. It is readily apparent that if the position of 
the furrows varied a few inches from one irrigation to another the sam¬ 
ples drawn 9 inches from the new furrows might be equidistant be¬ 
tween the old furrows, or possibly less than 9 inches from an old furrow. 
As the samples for analysis were made up of six borings, it seems reason¬ 
able to suppose that the results before irrigation would indicate a more 
even distribution of nitrates than the samples drawn after the last irriga¬ 
tion unless the location of the furrows were run at exactly the same point 
for each irrigation. 
The second irrigation showed a very marked lateral movement, which 
was apparent even at a depth of 30 to 42 inches. Before irrigation the 
nitric nitrogen amounted to about 4.5 mgm. 9 inches from the furrow and 
6.5 mgm. 18 inches from the furrow. After irrigation the nitric nitrogen 
9 inches from the furrow was reduced to 3.2 mgm., while the amount 18 
inches from the furrow was increased to 30.8 mgm. The lateral move¬ 
ment was also marked in the second, third, and fourth depths. The effect 
of the third and fourth irrigations, like the first and second, caused 
marked changes in the lateral distribution of the nitric nitrogen. During 
the fourth irrigation the supply in the upper 6 inches 9 inches from the 
furrow fell from 4.9 to 0.5 mgm., while the supply equidistant between 
the furrows rose from 5.5 to 21.9 mgm. 
Plot B has received no fertilizer, and the nitrate supply was very low. 
However, a comparison of the nitrate content 9 inches from the furrow 
with that 18 inches from the furrow showed that there has apparently 
