242 
Journal of Agricultural Research 
Vol. IX, No. 7 
furrow system. Under the overhead system it would seem that the 
nitrates which are formed or carried above the feeding roots by capillary 
action between irrigations may be leached down within reach of the roots 
with every application of water. On the other hand, the results secured 
during the season of 1915 indicate that much nitric nitrogen may be 
carried below the reach of the roots if too much water is applied. 
DISTRIBUTION OF NITRIC NITROGEN IN BASIN-IRRIGATED SOILS 
In basin irrigation the field is laid off into compartments, or checks, 
wholly surrounded by levees, with a tree in the center of each. The 
water is admitted at the upper end; and, if the basin is properly con¬ 
structed, the water spreads uniformly over the bottom of the compart¬ 
ment, or basin. Under this system of irrigation there is less opportunity 
for a lateral movement of the water, such as takes place under the furrow * 
system, in which the water is applied in small streams several feet apart. 
The distribution of nitrates in basin-irrigated soils was determined by 
selecting a strip of soil 2 inches in width and from 40 to 48 inches in length 
and removing small blocks of soil having a dimension of 2 by 4 by 3 inches 
until all the soil was removed to a depth of 12 or 15 inches. The nitric 
nitrogen in each block of soil was determined separately. In three of the 
basins studied a large number of borings were made in the bottom of the 
trench in foot-sections to a depth of 48 inches, and the average nitrate 
content of each 12-inch section determined. The distribution of nitrates 
in basin-irrigated and mulched soils is shown in Table XXVIII. 
Table XXVIII .—Distribution of nitrates in basin-irrigated soils 
[Results expressed as milligrams of nitrogen per ioo gm. of soil] 
Locality and date of 
sampling. 
Mulch. 
Depth. 
X 
2 
3 
4 
S 
6 
7 
8 
9 
10 
XI 
12 
Aver¬ 
age. 
Whittier, Aug. 30, 
1916, 
J-Bean straw.... 
Inches . 
0- 3 
3 - 6 
6- 9 
9-12 
12-24 
1.76 
1.16 
1* Si 
i. S 8 
X.62 
1.41 
2.00 
1.76 
2 - 35 
1-34 
2.25 
3 - OS 
2.98 
i -34 
1.16 
2.25 
3 . 8 s 
.88 
• 57 
•74 
3-97 
i -37 
.81 
. 60 
3-97 
1.65 
•74 
•99 
4.02 
1.72 
3-33 
.60 
4-35 
2.00 
1.23 
.46 
4.12 
2-35 
1.62 
•74 
3-30 
1-52 
1.52 
X.28 
a. 
24-36 
o * 7 a 
2.63 
. 36-48 
Plot 4. Citrus Experi¬ 
ment Station grove, 
Arlington, Sept. 12, 
1916. 
^Alfalfa hay.... 
i 
0-3 
3 - 6 
6- 9 
9-12 
12-24 
1-97 
1.02 
.67 
1.30 
2*35 
x.06 
1.23 
1-37 
3-77 
1.41 
1.58 
1. 72 
3-44 
2.00 
2.00 
i-Si 
3 * 54 
2-35 
2.42 
2.49 
2.97 
2.77 
3.12 
3-19 
3.82 
2. 25 
2.49 
2.63 
3-86 
3.16 
2.46 
2. 21 
3-65 
3- 26 
3-72 
3 -Si 
4-42 
2.49 
3-40 
3-12 
4 * 56 
3-25 
2.67 
3-74 
3-44 
2.07 
2.81 
2.56 
2.25 
3-48 
2.26 
2.38 
2 -45 
24-36 
3 * 93 
. 36-48 
!• SS 
T. fir 
Plot 27. Citrus Ex¬ 
periment Station 
grove, Arlington, 
ra rnt A 
■Barley straw.. 
O- 3 
3“ 6 
6- 9 
9-12 
12-24 
1-37 
.46 
• 46 
•«S 
•71 
•as 
2.00 
•39 
.88 
.32 
• as 
•IS 
•95 
•39 
.46 
•IS 
.81 
•as 
•IS 
.04 
1.16 
•as 
.17 
•IS 
•S 3 
.29 
. 16 
.11 
•SO 
.29 
. 11 
. 11 
•67 
•25 
•IS 
.11 
.64 
•32 
.18 
•IS 
•SO 
•25 
• ix 
• 11 
.60 
• 25 
.18 
. 11 
I. 05 
.78 
•30 
•36 
•IS 
WvpU iZ| 
24-36 
• is 
r 36-48 
• 29 
Riverside, July 27, 
1916. 
Highgrove, July 27, 
1916. 
|Alfalfa hay.... 
. .do.. 
o ~ 3 
3 “ 6 
6- 9 
9-12 
12-15 
0- 3 
3- 6 
6- 9 
9-12 
. 12-15 
•32 
.18 
. 11 
.04 
.08 
1.09 
.60 
.46 
.46 
•‘39 
•32 
•IS 
.08 
.04 
.08 
1.02 
.60 
•39 
.46 
•32 
•32 
. 11 
.04 
.18 
. 11 
1.23 
.81 
•32 
.46 
•39 
•32 
.ix 
.08 
. 11 
. 11 
1.06 
.67 
•39 
•53 
•39 
•as 
. 11 
. 11 
.04 
. 11 
1.09 
•S 3 
•39 
•SO 
•32 
.29 
•IS 
.08 
.08 
.08 
.88 
.46 
•39 
.60 
•32 
•32 
•39 
.11 
.08 
.08 
1.06 
•39 
•as 
.46 
•25 
•39 
.18 
. 11 
. ix 
.08 
.96 
•39 
•32 
•32 
.29 
. 11 
.11 
.18 
.04 
•S 3 
•32 
•25 
.32 
•as 
•39 
. 11 
. 11 
. 11 
.04 
•39 
•32 
•32 
•32 
•35 
.29 
•IS 
.08 
•as 
.08 
•S 3 
•32 
.29 
•as 
•32 
•32 
. 11 
• is 
. 11 
.04 
.46 
•39 
•39 
.60 
•32 
• 57 
•32 
•IS 
. 10 
. 11 
.08' 
.86 
.48 
•35 
•44 
•32 
