May 14, 1917 
Soil Nitrogen and Nutrition of Citrus Plants 
211 
Tables XIV to XVI show that the ammonia content of the soils is 
generally highest in the upper 6 inches, regardless of whether the soils 
have received heavy applications, light applications, or no nitrogenous 
fertilizer. It is also seen that the ammonia content of the unfertilized 
soils is almost, if not quite, as high as the fertilized soils, which would 
indicate that the ammonia formed in the decomposition processes under 
the field conditions does not remain in the soil, as does the ammonia 
formed when large applications of dried blood are added in laboratory 
experiments. It also appears that the rainfall has little effect on the 
distribution of ammonia, arid a large number of data collected in later 
studies have shown that the lateral movements of the irrigation water, 
while it caused a very uneven distribution of nitrates, had very little 
effect on the distribution of ammonia. A comparison of the data pre¬ 
sented in Tables XIV and XVI shows that the nitrogen as ammonia 
in the unfertilized soils is frequently greater than the nitrogen as ni¬ 
trates; and, as the ammonia seems to be quite uniformly maintained 
throughout the year, its value as a source of nitrogen for Citrus plants 
becomes a matter of importance. 
Table XV .—Seasonal variation in ammonia in furrow-irrigated soils receiving no nitrog¬ 
enous fertilizers. September, IQ14, to August, 1915* inclusive 
[Results expressed as milligrams of nitrogen per ioo gm. of soil] 
Period. 
Plot B. 
Depth.inches. . 
0-6 
6-18 
18-30 
0-6 
6-18 
18-30 
0-6 
6-18 
18-30 
19x4. 
September... 
0.74 
0.74 
0.46 
0.46 
a 46 
0.46 
a 74 
0.46 
O.46 
October. 
• 74 
•57 
.46 
.46 
.46 
.46 
•57 
.46 
.18 
November. 
.81 
•25 
. 18 
. xo 
.18 
•25 
•53 
•53 
* 46 
December. 
.69 
•32 
.18 
.46 
•39 
.18 
.67 
•36 
.35 
1915- 
January. 
.67 
.46 
•43 
.67 
•53 
.29 
.67 
•39 
.23 
February . 
.46 
.25 
. XX 
•39 
•25 
. 11 
.60 
.46 
. l8 
March. 
.46 
•32 
• 36 
. 60 
•39 
. 18 
•74 
•39 
• 25 
April . 
•25 
. 22 
.18 
•39 
. 22 
. II 
•50 
.29 
.18 
June .. 
•36 
. it 
.04 
•53 
•29 
. 08 
.60 
•39 
•15 
July. 
.29 
•25 
.08 
•39 
. 22 
•15 
.46 
.32 
. XI 
August. 
. 22 
. IX 
08 
•25 
.08 
. 01 
,29 
. 18 
.ox 
Plot D. 
Plot I. 
Period. 
Plot J. 
Plot M. 
Plot R. 
Plot T. 
Depth.inches.. 
0-6 
6-18 
18-30 
o-6 
6-18 
18-30 
0-6 
6-18 
18-30 
0-6 
<hl8 
18-30 
1914. 
September. 
0. 74 
0. 60 
0.46 
O. 74 
0. 60 
0.46 
0. 88 
0. 74 
O.32 
0.88 
O. 60 
0.46 
October. 
•74 
.46 
.46 
.88 
•57 
•57 
.86 
.46 
•32 
•74 
.46 
.46 
November. 
.81 
.67 
■25 
•74 
•32 
.25 
1.09 
. 60 
•39 
.88 
• 74 
•32 
December. 
*74 
.46 
•32 
•85 
•74 
.46 
1.09 
•39 
•25 
•85 
•36 
. x8 
1915- 
January. 
.88 
.67 
. 22 
.67 
•53 
•25 
.88 
•39 
•36 
.67 
•39 
•32 
February. 
. 60 
•43 
. l8 
•53 
•25 
.08 
•53 
•25 
.08 
•53 
•32 
.04 
March. 
.81 
•36 
•25 
•74 
53 
•39 
•55 
•39 
•25 
.81 
.46 
•32 
April... 
•50 
.46 
• 29 
•50 
•74 
.29 
•57 
•43 
*36 
1. 00 
.60 
•37 
June. 
•74 
•39 
.18 
•43 
.18 
•25 
. 60 
.46 
.32 
.67 
.18 
•15 
July. 
.67 
•39 
. IX 
.60 
•39 
.18 
•57 
•25 
. 22 
.46 
•25 
•15 
August.... 
•43 
•IS 
.OI 
•50 
•15 
.01 
•43 
.18 
• ox 
•39 
. 22 
•15 
