212 
Journal of Agricultural Research 
Vol. IX, No. 7 
Table .XVI .—Seasonal variation in ammonia in furrow-irrigated soils receiving light 
applications of nitrogenous fertilizers. September, IQ14, to August, 1915, inclusive 
[Results expressed as milligrams of nitrogen per 100 gm. of soil] 
Period. 
Plot E. 
Plot N. 
Plot K. 
Plot P. 
Depth. inches. . 
0-6 
6-18 
18-30 
0-6 
6-18 
18-30 
0-6 
6-18 
18-30 
0-6 
6-18 
18-30 
« , 19141 
September. 
0* 74 , 
O. 46 
a 46 
a 88 
O. 60 
0. 46 
0.88 
0. 70 
0.46 
a 88 
o- 46 
0. 46 
October. 
• 74 
•57 
■57 
•74 
.46 
.46 
•74 
.46 
.46 
.88 
.46 
.18 
November... 
. 60 
. 22 
.18 
•74 
• 39 
• 15 
.67 
.88 
.18 
.81 
•39 
.18 
December... 
.67 
.46 
.18 
•99 
•50 
•39 
•74 
.88 
•25 
.88 
.46 
•39 
1915- 
January. 
.78 
*50 
. 22 
.71 
.60 
.29 
.67 
.46 
.32 
.81 
•43 
• 36 
February. 
*53 
. II 
. 11 
.46 
.29 
.08 
•.60 
•39 
•15 
.46 
•32 
.08 
March. 
.78 
•50 
. 22 
•63 
•53 
•25 
.88 
•43 
•36 
•79 
•43 
• 15 
April. 
.81 
.18 
. 22 
•99 
•54 
•25 
.60 
.29 
.08 
. 60 
. 29 
• 15 
June.. 
.67 
•25 
•25 
•74 
•39 
.18 
.67 
•32 
.18 
•53 
. 22 
• 15 
July.. 
•50 
. 22 
. II 
. 60 
•36 
.18 
.46 
•29 
.18 
.67 
• 25 
.18 
August. 
•39 
•IS 
• 07 
*44 
. 22 
. 01 
.29 
. n 
.04 
•50 
. 22 
.08 
In the preliminary studies on the distribution of nitric nitrogen under 
the furrow system of irrigation it was observed that the supply of nitrates 
near the surface was reduced near the furrows during an irrigation. 
However, no increase in nitrates could be detected in the deeper layers 
to account for the reduction which apparently took place near the sur¬ 
face. Before and after the June irrigation of 1915, samples were drawn, 
9 inches from the furrows, from 10 plots. Each sample for analysis was 
made up of six borings, each one located 9 inches from a furrow. The 
holes made in removing the first samples were carefully filled in, and the 
second set of borings was made about 12 inches from the first, but the 
same distance from the furrows. 
In order to bring out more clearly the seasonal variation and the effect 
of fertilizers on the nitrate and ammonia content of furrow-irrigated 
Citrus soils, the data presented in Tables XI to XVI are summarized in 
Tables XVII and XVIII. 
Table XVII .—Average nitrate content of Citrus Experiment Station soils. September, 
IQ14, to August, igis, inclusive 
[Results expressed as milligrams of nitrogen per 100 gm. of soil] 
Treatment and depth in 
inches. 
Sept. 
Oct. 
Nov. 
Dec. 
Jan. 
Feb. 
Mar. 
Apr. 
May. 
June. 
July. 
Aug. 
Seven plots receiving 145 
pounds of nitrogen per 
acre in commercial fer¬ 
tilizers: 
0-6..... 
5 * 67 
• 97 
A* 77 
3-98 
« 73 
3*62 
0.31 
1.68 
• 75 
.80 
.82 
2.07 
•75 
a. 
0.42 
At 
2.65 
• 72 
•54 
• 6l 
2.99 
•38 
3*40 
&-18. 
*#• / / 
O* 77 
18-30. 
.60 
• to 
• 70 
• /O 
- 22 
*5 
i* 15 
. OI 
.40 
•34 
30-42. 
* 0 * 
* *0 
• 2 3 
1 .37 
. 04 
. 8<7 
.40 
• 54 
•45 
Two plots receiving ap¬ 
proximately 145 pounds 
of nitrogen per acre as 
barnyard manure: 
0-6. 
2. 56 
.67 
•39 
1.96 
• 52 
• 53 
2 * 1 A 
1.69 
• 74 
•25 
T 
• 07 
•57 
*36 
.40 
• 3 ° 
At 
1-25 
.29 
•23 
• 30 
I- 55 
.22 
. 20 
6-18. 
18-30. 
30-42. 
A* 44 
• 37 
• 32 
• 51 
• 30 
• 25 
•38 
.85 
■ 29 
.27 
•50 
. A ? 
. OI 
•51 
•31 
i* 30 
•32 
•13 
•15 
Four plots receiving 48.60 
pounds of nitrogen per 
acre in commercial fer¬ 
tilizer: 
0-6....,. _ 
I.08 
I* 02 
• AQ 
1.08 
t. AC 
.87 
A *7 
. 16 
• 42 
1.42 
.41 
.27 
• 3 ° 
.58 
•57 
• 29 
.92 
6-18. 
•37 
.48 
A* 
* 37 
• °9 
I* Oo 
• 25 
1.15 
.18 
18-30. 
» CO 
• 22 
• 07 
, TO 
# 27 
. 12 
•25 
.38 
.19 
• 17 
. 21 
30-42. 
• 24 
• 14 
• 06 
• 19 
.14 
. 11 
.07 
Seven plots receiving no 
nitrogenous fertilizers: 
0—6.. 
1 02 
• 07 
.84 
.80 
•15 
•25 
•23 
*23 
• 19 
r Q 
* 25 
.40 
• IO 
• 34 
6-is.. 
- CO 
• y / 
.38 
• AQ 
• 7 ° 
• 61 
.20 
. 70 
18-30. 
•36 
. 16 
• 34 
.18 
.13 
• 3 ° 
* 3 * 
.07 
.09 
30-42 . 
• 4W 
* 10 
TO 
. 20 
• 11 
• 08 
. 11 
• 13 
.07 
* 19 
.20 
. 12 
• x 3 
. 04 
