May 14,1917 
Soil Nitrogen and Nutrition of Citrus Plants 
231 
observed that there is no one boring which was consistently high, but 
that there was an appreciable movement of nitrates away from the fur¬ 
rows. The nitrate supply within reach of the roots was higher in this 
plot than in plot 14, which was also a control. Nearly 50 per cent of 
the nitrates in the upper 4 feet of soil were found in the upper 3 inches. 
In plot 36 the samples were taken between the furrows run at a distance 
of 24inches. The nitrate content of thesurface 3 inches variedfrom 3.86 to 
88.7 mgm. The highest amount found below the surface 3 inches is 7.26 
mgm. Notwithstanding the large accumulation of nitrates in the surface 
soil, it is seen that the nitrate supply in this soil within reach of the feeding 
roots was abundant. The increase at the lower depth was presumably due 
to the leaching down by the winter rains of the nitrates produced during 
the previous season. 
It would seem that the fertilized plots in this grove contained enough 
available nitrogen above the feeding roots to supply the needs of the trees 
from 1 % to 3 years. Even the unfertilized soils contained more nitrogen 
* above the feeding roots than would be removed in an average crop of fruit. 
In order to determine the distribution of nitric nitrogen in soils differ¬ 
ing in type and treatment, samples were taken in representative groves 
from widely separated districts. Table XXIII shows the distribution 
of nitrates in soils from Covina, Corona, and Lordsburg. 
Table) XXIII .—Distribution of nitrates at right angles to furrows in soils at Covina, 
Corona, and Lordsburg, Cal. 
[Results expressed as milligrams of nitrogen per ioo gms. of soil] 
Locality and samp¬ 
ling date. 
Depth. 
Boring No. 
Aver¬ 
age. 
1 
2 
3 
4 
5 
6 
7 
8 
Covina (sampled 
Corona (sampled 
Aug. 14,1916). 
Lordsburg, soil A 
(sampled Aug. 23, 
1916)....*• • 
Lordsburg, soil B 
(sampled Aug. 23, 
iai 6 ) .. 
Inches, 
o- 3 
3 “ 6 
6- 9 
9-12 
12-15 
O- 3 
3 - 6 
6- 9 
9-12 
1:2-15 
0- 3 
3 - 6 
6- 9 
9-12 
12-24 
24-36 
0- 3 
3" 6 
6- 9 
9-21 
. 21-33 
■0- 3 
3 - 6 
6“ 9 
9-12 
12-24 
24-36 
. 36-48 
0- 3 
3" 6 
6- 9 
9-21 
21-33 
33-45 
0.14 
.81 
*25 
.46 
7*95 
•99 
.84 
1.02 
•S6 
•25 
.67 
•25 
6*73 
•74 
•57 
.18 
.60 
10.89 
1.09 
.67 
•57 
•43 
•74 
.88 
•50 
•IS 
11.47 
1.86 
.66 
•17 
.29 
21.88 
5 -IS 
1-37 
.29 
•25 
7.60 
.67 
•25 
.50 
7.29 
1.69 
.90 
•45 
.60 
21.18 
28.18 
3-75 
.88 
•39 
20. 27 
I.72 
.92 
.64 
13.66 
2.18 
.67 
•32 
•39 
17-96 
5-57 
4-59 
I.02 
.67 
I. 65 
•53 
•32 
.25 
6.52 
•93 
•33 
.24 
.27 
9 - 56 
7 * 11 
3*40 
•95 
•74 
3*12 
.67 
.18 
• 25 
2.74 
•50 
•30 
.38 
•34 
7 * 57 
i -51 
.81 
•95 
.64 
•39 
•15 
•50 
.18 
0.32 
.29 
. 22 
•25 
1.09 
•43 
•35 
.28 
•35 
.36 
•25 
.18 
8.07 
1.04 
•57 
.28 
.40 
12. 26 
6* 25 
1.97 
•74 
•49 
5-63 
.65 
•45 
•30 
1.58 
.46 
14-04 
5-24 
1 - 57 
•39 
•32 
19-34 
2- 18 
•53 
•24 
•15 
.18 
•25 
n -37 
1-55 
•44 
1.27 
.18 
•39 
5.82 
1.44 
18.94 
6*34 
1*93 
10. 75 
3-09 
1.41 
9.84 
6.65 
1.41 
14.88 
3* 16 
I. 76 
12. 29 
8.69 
2. 28 
17-54 
4.42 
1.51 
3 * 75 
• 85 
Lordsburg, soil C 
(sampled Aug. 23, 
tqt6^ ... 
1.09 
•53 
. 22 
17-54 
1.16 
•57 
•32 
25.64 
4-52 
.78 
•32 
24.64 
4-73 
.81 
•25 
20.34 
2.60 
.46 
•25 
16.00 
2.14 
•39 
.18 
12.08 
•43 
.46 
.18 
•78 
•25 
.18 
Lordsburg, soil D 
(sampled Aug. 23, 
IOl6^ . 
.29 
. 60 
9.21 
. 60 
•39 
10.68 
1. 76 
•32 
20.90 
4. xo 
. 60 
14-74 
*85 
.46 
1.30 
i-13 
•39 
2.14 
•32 
. . . 
82981°—17- i 
