Transpiration as a Factor in Crop Production. 145 
Table 60. — Total amount, in pounds, of nitrogen, acid soluble 
potash, and phosphoric acid contained in the soil of the average 
potometer in each group of the fertility series. 1911 and 191 U. 
Type of soil 
Plant food elements in each potometer 
Without manure 
With manure 
N 
Acid soluble 
N 
Acid soluble 
K 2 0 
P 2 o 5 
K 2 O 
P 2 o 5 
Pounds 
Pounds 
Pounds 
Pounds 
Pounds 
Pounds 
(1) 
(2) 
(3) 
(4) 
(5) 
(6) 
YEAR 1911 
Infertile 
0.177 
1.039 
0.157 
0.222 
1.063 
0.203 
Intermediate 
.232 
1.054 
.142 
.273 
1.092 
.191 
Fertile 
.444 
1.603 
.200 
.498 
1.638 
.246 
YEAR 1914 
Infertile 
.302 
.785 
.272 
.337 
.811 
.307 
Intermediate 
.433 
1.138 
.379 
.469 
1.156 
.414 
Fertile 
.528 
1.392 
.480 
.563 
1.419 
.515 
ment Station. In 1914 the surface 10 inches of a similar soil was 
taken from an adjoining productive cornfield. 
(3) Intermediate fertile soil. This soil was prepared in 1911 
by filling the bottom two feet of the potometer with the 2d and 
3d foot of the infertile soil; and for the upper foot an equal* mix- 
ture of the surface foot of the infertile and fertile soils was used. 
In 1914 a uniform mixture was prepared by combining equal 
weights of the infertile and fertile soil. An intermediate stage of 
fertility was evidently secured each year, since in comparison 
with the infertile and fertile soils, the yields of dry matter were 
respectively 113, 184, and 270 grams in 1911 and 142, 330, and 
417 in 1914. The higher yields in 1914 are due in large part to 
the fact that only surface soil was used. 
RESULTS OF THE TWO SOIL FERTILITY EXPERIMENTS. 1911 AND 1914. 
The soils placed in the potometers in 1911 evidently deterio- 
rated after the first year, because the plants have each year since 
acquired a yellowish color and have been comparatively unpro- 
ductive. Altho the data for the last three years from these soils 
are summarized in Table 66, the results must be regarded as 
abnormal. They are given more to show the possible deterio- 
rating effect on soil of long confinement in cans. 
