May 14,1917 
Soil Nitrogen and Nutrition of Citrus Plants 
233 
About 90 per cent of the nitrates in the surface foot of soil were located 
in the upper 6 inches, in which no feeding roots could be found. 
Table XXIV .—Distribution of nitrates at right angles to furrows in soils at Orange , 
Anaheim , and Whittier , Cal . 
[Results expressed as milligrams of nitrogen per 100 gm. of soil] 
Locality and date 
of sampling. 
Depth. 
Inches. 
Orange (sampled 
Aug. 29,1916)_ 
Anaheim (sampled 
Aug. 29.1916).... 
Whittier (sampled 
Aug. 30,1916). 
3 
3 ” 6 
6- 9 
9-12 
o- 3 
3- 6 
6- 9 
9^12 
o- 3 
3 - 6 
6- 9 
9-12 
12-24 
24-36 
36-48 
48-60 
Boring No. 
1 
2 
S 
4 
5 
6 
7 
8 
10.02 
1.97 
1.06 
.67 
•85 
•43 
•25 
.29 
18.97 
I- Si 
1.87 
3-44 
19.71 
3- 26 
1.02 
.46 
2.98 
3-19 
1.27 
• 7 i 
1939 
8.89 
2.19 
6.96 
29. 58 
7.81 
2. 00 
I. 20 
7-99 
I. 72 
•74 
•32 
36.08 
6.79 
3 - 76 
5- 61 
9.14 
1.86 
1.02 
1.13 
1.16 
•32 
•39 
•32 
9.67 
8.64 
3*69 
3-39 
1.44 
.81 
.67 
0. 78 
1.09 
•99 
•43 
. 60 
.22 
•39 
.29 
.04 
24.04 
2- 72 
2-34 
1.67 
9.49 
1.87 
1.04 
.66 
1*58 
x. 29 
3-30 
3-47 
.82 
•32 
Aver¬ 
age. 
17.11 
2.85 
1.17 
•8s 
3 - 24 
1.08 
•59 
•31 
19.61 
4 - 43 
2.12 
3*17 
4.17 
5 - IS 
4.14 
5*40 
The Anaheim soil, although comparatively low in nitric nitrogen, 
showed a very uneven distribution, which was apparently due to the 
lateral movement caused by the irrigation water. 
The Whittier soil was unusually rich in nitric nitrogen, and, while it 
showed a very large accumulation at the surface, the lateral distribution 
was more uniform than in most furrow-irrigated soils. It would seem 
that several crops of fruit must be grown before the nitrates in this soil 
can be utilized, and in the meantime the irrigation and rainfall will prob¬ 
ably have carried away much of the supply, causing considerable loss. 
During the month of August samples were taken from groves at 
Redlands, Highland, and Rialto. The distribution of nitrates in these 
soils is shown in Table XXV. The two soils from the Redlands district 
show that a large percentage of the nitric nitrogen which they contain is 
found in the upper 3 inches of soil, and also that the lateral distribution is 
very uneven. 
It was apparent that the available nitrogen in grove A was not sufficient 
for the needs of the trees, as they showed the characteristic nitrogen- 
starved appearance. However, if the nitrates which have accumulated 
in the surface 3 inches of this soil could be brought within reach of the 
roots, the nitrogen supply would probably be sufficient for the produc¬ 
tion of a fair crop of fruit. 
The trees in grove B seemed to get sufficient nitrogen, as the foliage 
was in good condition and they bore a good crop of fruit. On comparing 
the nitrate content of soils A and B below the upper 6 inches, it is seen 
that the latter contains about twice as much nitric nitrogen as the former. 
Notwithstanding the fact that considerable quantities of commercial 
nitrogen have been added during the season, the nitrate content of the 
