May 14,1917 
Soil Nitrogen and Nutrition of Citrus Plants 
215 
throughout the entire series of eight plots, it would seem that there must 
have been a movement of nitrates away from the furrows, causing a re¬ 
duction near the furrows and an increase 18 inches from the furrow. At 
a depth of 6 to 18 inches the nitrates were apparently moved more 
slowly; however, the amount found 9 inches from the furrows is some¬ 
what less after irrigation in all the soils except soil Q, while at a dis¬ 
tance of 18 inches from the furrow there is a gain in all of the soils 
with the exception of soil L. At a depth of 18 to 30 inches the nitric 
nitrogen is very low, and no consistent reduction is shown in the sam¬ 
ples taken 9 inches from the furrow; but a consistent gain is shown in 
samples 18 inches from the furrow, indicating that a lateral movement 
has taken place at this depth. The results secured at a depth of 30 to 42 
inches are very similar . 
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to those obtained for 
a depth of 18 to 30 
inches. 
During the season of 
1916 extensive studies 
were carried out on the 
lateral movement of 
nitric nitrogen in fur¬ 
row-irrigated soils. At 
the beginning of the 
irrigation season small 
squares were selected 
in each of 14 plots. 
Samples were drawn 
from these squares just 
before and as soon 
after irrigation as the 
moisture conditions ftG * a - 
would permit. One set 
of samples was taken frojn the bottom of the furrows, a second set 
about 9 inches from the furrows, and a third set about 18 inches from the 
furrows. The furrows are approximately 36 inches from center to center; 
therefore the third set of samples were drawn from a point about midway 
between the furrows. Each sample for analysis was made up from six 
borings, which were located within the square formed by four trees. 
The distribution of the borings within the square is shown in figure 2. 
The samples were drawn from the same square before and after each 
irrigation. , The holes made in taking the first set of samples were filled 
in and the borings made in securing the second set of samples were 
located as near the first borings as practicable. As the furrows were 
about 6 inches deep and the samples drawn after the furrows were run 
82981°—17 - 3 
+ 
Diagram showing the location of soil-sample borings made in 
studying the lateral movement of nitrates in furrow-irrigated soils. 
