208 
Journal of Agricultural Research 
Vol. IX, No. 7 
Table XII shows the distribution of nitric nitrogen in soils receiving 
light applications of nitrogenous fertilizers, and in these soils it is seen 
that the accumulation of nitric nitrogen in the surface 6 inches is far 
less than in the heavily fertilized soils. It is also seen that the amount 
found at a depth of 6 to 18, 18 to 30, and 30 to 42 inches is somewhat 
lower than in the heavily fertilized soils. The effect of the rainfall in 
carrying down the nitrates is shown in the results on the lightly ferti¬ 
lized soils as well as on the heavily fertilized soils. The smaller percent¬ 
age accumulation of nitrates at the surface during the irrigation season 
is probably due to the fact that all of the materials added to the lightly 
fertilized plots was added in one application in the early spring and 
plowed down, and as the amount added was not in excess of the needs 
of the tree, much of the nitrogen was probably assimilated before the 
upward movement of the soil moisture had carried it beyond reach of 
the roots. 
Table; XII. — Seasonal variation in nitrates in furrow-irrigated soils receiving light appli¬ 
cations of nitrogenous fertilizers. September , 1914, to August , 1915, inclusive 
[Results expressed as milligrams of nitrogen per ioo gm. of soil] 
Period. 
Plot E. 
Plot N. 
Depth.inches.. 
1914. 
September. . . 
October. 
November. 
December. 
191s. 
January. 
February. 
March..,. 
April...i.. 
May. 
June. 
July. 
August... 
0-6 6-18 18-30 30-42 
0-6 
6-18 18-30 30-42 
September. 
October... 
November. 
December., 
January.. 
February. 
March..., 
April.... 
May. 
June. 
July. 
August... 
1914- 
1915. 
0.88 
.88 
1.02 
1.16 
•97 
.18 
•SO 
i -37 
• 55 
1.30 
1.06 
x.02 
o. 46 
•57 
•32 
• 53 . 
•25 
.29 
. 21 
.22 
.84 
.29 
. 22 
.11 
o. 52 
.46 
»18 
. IX 
•39 
.29 
.18 
.29 
•25 
.22 
.08 
X .02 
1.02 
I. 14 
1.02 
•78 
•15 
•58 
I.44 
.69 
.6l 
X. 02 
x.os 
o. 11 
.46 
•32 
•15 
•39 
. 22 
. II 
•43 
•36 
.18 
.18 
•15 
o. 46 
•32 
•25 
.18 
.18 
•25 
.05 
•33 
.18 
.II 
•15 
.IX 
Plot K. 
PlotP. 
I . 02 
0.46 
0.46 
1.38 
O. 46 
0.46 
1.02 
.46 
•74 
1.16 
.46 
•47 
I . 02 
•32 
.18 
1.14 
.18 
•25 
•99 
•32 
. 11 
X.02 
.46 
.25 
.91 
.22 
. 11 
•83 
.22 
. 11 
•15 
.18 
.60 
. 18 
•32 
.28 
.81 
•25 
•32 
.88 
•25 
. 11 
X* 44 
.46 
•32 
O.32 
1-44 
•53 
•25 
•57 
•54 
•25 
. 22 
•53 
•53 
•34 
I.32 
.46 
. 11 
.04 
x. 08 
.06 
. 10 
99 
.18 
•IS 
.18 
.61 
* 25 
•25 
i- 5 i 
•36 
•15 
.01 
1.02 
. 11 
. 11 
>. 18 
• 41 
. 08 
.08 
By a comparison of the results presented in Table XIII with those of 
Tables XI and XII the effect of the application of the nitrogenous fertil¬ 
izers may be readily ascertained. The nitrate content of the heavily 
fertilized plots at a depth of o to 6 inches is far in excess of the amount 
found in the unfertilized plots. At, a depth of 6 to 18 inches, 18 to 30 
inches, and 30 to 42 inches the increase is much less marked, and in some 
