May 14,1917 
Soil Nitrogen and Nutrition of Citrus Plants 
247 
Soil 2 contained about 162 pounds of nitric nitrogen per acre on 
January 7 in the upper 3K feet. After the heavy rains between January 
7 and 26, the soil was found to contain only about 70 pounds to a depth 
of 90 inches. It would therefore seem that the loss of nitrogen in this 
soil from these rains was at least 100 pounds per acre. 
Soil 3 is a heavy clay soil which contained a considerable quantity of 
nitrogen at a depth of 6 to 18 inches on January 7. About three-fourths 
of the nitrates contained in this soil seems to have been lost by leaching 
between January 7 and 26. 
Soils 4 and 5 were taken from different parts of the same grove, and 
both were found to* contain considerable quantities of nitrates on Jan¬ 
uary 7. The loss in these soils must have amounted to well above 100 
pounds per acre as a result of the rainfall from January 7 to 26. 
Soil 6 contained only a little nitric nitrogen at the time the first set 
of samples was‘taken, but the amount found after the heavy rains is 
much smaller. The small amount of nitric nitrogen found from 66 to 90 
inches indicated that the nitrates removed from the surface layers in 
these soils had been carried well beyond the reach of the roots and 
beyond the depth where capillary action might be a factor in returning 
them to the surface layers. 
Prom September 30 to October 7, 1916, the rainfall at Riverside 
amounted to 1.80 inches. Immediately after these rains samples were 
taken from three soils at Riverside and one at Arlington. At least 75 
per cent of the nitric nitrogen in the first foot of these soils was located 
in the upper 3 inches before the rains. The distribution of nitrates in 
the soils after the rains is shown in Table XXIX. 
Table XXIX .—Effect of rainfall from September 30 to October 6, igi6 , on the distri¬ 
bution of nitrates in Citrus soils 
[Results expressed as milligrams of nitrogen per 100 gm. of soil] 
Plot A. 
Plot H. 
Depth. 
Boring No. 
Boring No. 
Aver¬ 
Aver¬ 
x 
a 
3 
4 
5 
6 
age. 
X 
2 
3 
4 
5 
6 
age. 
Inches. 
0-3. 
0. IX 
0 . XX 
O.XI 
0.04 
0.04 
0. ii 
0.09 
0.32 
1.02 
0. 22 
0. x8 
0.46 
0.50 
0. 45 
3-6 . 
z* 93 
.67 
x.02 
1.65 
1.16 
2.07 
1.42 
IS-10 
7-39 
1.30 
1.90 
4-38 
13* 20 
7. 21 
6-9. 
4 - 87 
6 - 55 
x- 93 
2-35 
3**9 
1. 72 
3-43 
6.20 
4-®3 
.88 
9. 70 
6.13 
3-75 
S-12 
J 7 -I 2 . 
.60 
2.00 
.67 
•32 
•39 
. 11 
.68 
2-35 
. 60 
.60 
1.16 
3-37 
1.23 
i- 55 
Soil from Arlington, Cal. 
Plot C. 
0-3 . 
• 4 * 
• 53 
•39 
•25 
•39 
•36 
•39 
.46 
•39 
.25 
.29 
•36 
•25 
•33 
3-6 . 
1-37 
X. 86 
•53 
•39 
•95 
•25 
.89 
4.66 
3* 02 
1. 79 
•53 
x. 02 
1. 51 
2.09 
6 -9 . 
•S 3 
.32 
.22 
•32 
•39 
•15 
•33 
4-52 
4*73 
2.42 
2.00 
x. 30 
1.44 
2.74 
9-12. 
•IS 
•25 
.XX 
.XX 
•15 
.04 
.14 
.67 
.88 
•99 
.88 
.60 
•47 
• 75 
82981°—17 - 5 
