May 14,1917 
Soil Nitrogen and Nutrition of Citrus Plants 
227 
between the furrows. As the highest concentration could not always be 
located from observation, it seemed necessary, in order to secure an' 
accurate knowledge of the distribution between furrows, to remove all 
of the soil in small blocks from one furrow to another. A special soil 
sampler was therefore designed, which made it possible to remove a 
block of soil 2 by 4 inches to any depth desired. As it was evident that 
a very high percentage of the nitrogen accumulated in the surface layers, 
the soil was removed in 3-inch layers. Each block of soil 2 by 4 by 3 
49 * 30 * 
1 ^"1 
■I II ■ 
■-I 
^0-42 
1 an 
L P 
1—1 
n In 
b-| 1 
LjJ 
r 
w-i ■ 1 ■- 
■ am ir> 
■J i- 
Jftj 
m 
/ST /ST ^77/. /ST 47*K 
a/o. ar/*?/?/&*r/OA/ 
Fig. 14.— Diagram showing the distribution of nitrates in plot S before and after irrigations. Season of 
1916. 
inches was analyzed separately. In some instances the soil below a 
depth of 12 to 15 inches was removed in 12-inch sections, a number of 
borings being made in the bottom of the trench to make up the sample 
for analysis. 
On August 7 samples were taken from five plots in the Citrus Experi¬ 
ment Station grove, as shown in Table XXI. All of the soil was removed 
in a 2-inch strip from furrow to furrow to a depth of 12 inches in plots 
A, B, G, and M, and to a depth of 15 inches in plot L. 
