206 
Journal of Agricultural Research 
Vol. IX, No. 7 
rence of the niter spots. The irrigation water was carefully analyzed 
and found to contain very small quantities of nitrates, which seemed to 
preclude the possibility of irrigation water being the source of the nitrates; 
neither did it seem at all possible that the nitrate accumulations in the 
Citrus soils of southern California could be derived from nitrate deposits 
occurring originally in the country rock. The rock from which these soils 
were originally derived are granitic in character, and, so far as the writer 
has been able to ascertain, contains little or no nitrogen. Furthermore, 
the virgin lands or cropped dry lands are generally very low in nitrogen 
and do not contain the brown spots so characteristic of furrow-irrigated 
lands. 
Table; XI .—Seasonal variation in nitrates in furrow-irrigated soils receiving heavy 
applications of nitrogenous fertilizers. September, IQI4 , to August , rp/5, inclusive 
[Results expressed as milligrams of nitrogen per 100 gm. of soil] 
Period. 
Plot A. 
Plot c. 
Plot F. 
Depth.inches.. 
0-6 
6-18 
18-30 
30-42 
0-6 
6r-l8 
18-30 
30-42 
0-6 
6-18 
18-30 
30-42 
1914- 
September. 
S-18 
0. 74 
0.46 
5.22 
1.02 
O' 60 
2.70 
o* 60 
0.32 
October... 
4. 14 
• 46 
• 46 
4.28 
.84 
.46 
x.98 
• 57 
*32 
November. 
3- 60 
* 39 
• 25 
3.84 
• 97 
• 25 
x. 44 
• 32 
.18 
December. 
4. 72 
•59 
.18 
2> 6l 
•94 
.18 
1.63 
.81 
•25 
„ 1915. 
January.. 
3. 51 
.88 
.18 
2* 72 
I* 02 
. IX 
1.30 
•43 
. 29 
February. 
, 15 
. 53 
i. 09 
• 25 
•39 
I. 23 
• 25 
• 29 
.83 
March. 
1.58 
.88 
.46 
O' 16 
.46 
.32 
• 25 
0.82 
• 32 
•29 
•32 
0.32 
April... 
2.08 
.88 
•58 
•8s 
•95 
•39 
• 71 
x.02 
.60 
.36 
•25 
•29 
May... 
• 3 i 
.62 
• 5 i 
•17 
.20 
•65 
•37 
.28 
•58 
•58 
. 22 
•25 
June.. 
1.99 
•57 
. 20 
•29 
1.77 
•35 
. 22 
•IS 
I. xo 
.22 
.18 
.08 
July*. 
3 -OS 
•25 
•29 
.29 
2.60 
•25 
.29 
. IX 
1.30 
. 11 
•15 
.08 
August.. 
2-Si 
. 22 
.06 
.06 
3*96 
.18 
. 10 
.08 
1.09 
•39 
.18 
. XX 
Plot G. 
Plot H. 
plot n. 
„ . I 9 I 4 - 
September. 
6. 62 
0.74 
0.46 
7.18 
x. 16 
0.60 
5. 7 $ 
0.98 
O' 74 
October. 
5.22 
• 74 
. 46 
6- 55 
• 57 
• 74 
4.60 
• 74 
X. 02 
November. 
4.54 
.66 
.18 
4.68 
• 74 
.46 
3.65 
• 32 
• 25 
December. 
4*17 
i-13 
,29 
4 - 59 
1.30 
•25 
3*75 
•99 
.18 
„ 1915. 
January. 
3. S 3 
• 74 
.18 
4.82 
x.51 
. 25 
3 * 23 
1. 22 
.1$ 
February. 
* 25 
1.10 
1. 71 
. 22 
I- 03 
!• 74 
. XI 
!• 06 
I. 64 
March. 
2.40 
.66 
.81 
o. 67 
2.65 
i-15 
.92 
0.95 
1.98 
•39 
•74 
0 .99 
April. 
2. 76 
•77 
.84 
•53 
2.80 
.60 
•S 3 
•87 
2.12 
.60 
•71 
1.02 
May. 
.69 
•95 
. 20 
•13 
•50 
•36 
•30 
•49 
•43 
•54 
•36 
•57 
June. 
3-52 
.86 
•SO 
•59 
4-21 
.78 
.64 
•97 
2.32 
*57 
.64 
•50 
July.;. 
2. 27 
•13 
.28 
.04 
3*33 
•39 
•32 
.60 
2-39 
.64 
.46 
.46 
August. 
4*38 
•30 
.78 
.60 
3*95 
.46 
.48 
•56 
3-54 
•39 
•71 
x. x6 
Plot 0. 
Plot Q. 
Plot S. 
1914. 
September. 
2. 42 
0. 74 
0.46 
4. 98 
0.88 
0.60 
4 * 70 
X' 30 
O' 74 
October... 
1.94 
• 46 
• 74 
4.42 
• 74 
• 74 
4.10 
X. 02 
i. 02 
November.;. 
1.04 
• 43 
.46 
3 - 78 
!• 02 
.32 
3* 82 
X. 02 
• 53 
December. 
1.74 
.66 
•25 
3-48 
1.78 
. x8 
3-05 
1-79 
•38 
1915. 
January. 
2.00 
. 60 
• 32 
3. 57 
!■ 23 
•32 
3.91 
I. 44 
• 43 
February. 
. 25 
.48 
.86 
• 5 ° 
2.18 
• 99 
• 67 
I- 79 
1.16 
March. 
■25 
•25 
.67 
O. 54 
1.85 
x> 02 
1.30 
I.09 
.81 
.81 
1.09 
1.08 
April. 
•53 
•36 
•56 
• 5<5 
2-45 
X. 23 
1.44 
•74 
1.30 
.81 
X. XO 
1.08 
May... 
.64 
.46 
•41 
•36 
. 60 
.60 
.48 
•34 
. 20 
•57 
•59 
.67 
June. 
1.41 
•36 
.27 
•50 
2. 73 
.85 
•79 
.81 
2.00 
1.09 
.78 
•95 
July.. 
1.79 
•32 
•25 
•15 
3-72 
.46 
.29 
•39 
3.58 
•53 
.60 
. 60 
August. 
1.51 
.25 
.08 
.18 
3.12 
•53 
•74 
• x6 
a -35 
•39 
•92 
•53 
