Journal of Agricultural Research 
Vol. IX, No. 3 
88 * 
SUMMARY OR EXPERIMENTAL RESULTS 
The essential results of the io preceding experiments are summarized 
in Table XXII. 
Table XXII .—Summary of results of Experiments I to X 
Experi¬ 
ment No. 
Plant 
grown. 
Element tested. 
Complete nutrient 
solution. 
Propor¬ 
tion of 
roots in 
com¬ 
plete 
solu¬ 
tion. 
Total 
amount 
of ele¬ 
ment 
ab¬ 
sorbed.® 
Amount 
of ele¬ 
ment 
ab¬ 
sorbed 
per 
gram of 
roots.® 
Ratio 
of root 
to top.® 
Per ct. 
I. 
Rice. 
Nitrogen. 
Neutral. 
en 
77 
145 
12* 
IT. 
Com. 
.do. 
.do. 
56 
76 
148 
TAC 
12* 
Ill. 
Rice. 
.do. 
.do. 
74 
11 
X 22 
Ill. 
.. .do. 
.do. 
Neutral, double ni- 
l62 
II* 
trogen. 
11 
IV. 
.. .do. 
.do. 
Neutral. 
27 
55 
226 
133 
V. 
.. .do. 
Phosphorus. 
.do. 
47 
<0 
76 
128 
122 
V. 
...do. 
.do. 
Neutral, double phos¬ 
78 
1*7 
IIS 
phorus. 
VI. 
...do. 
.do. 
Neutral. 
33 
6$ 
l6o 
120 
VII. 
...do. 
Potassium. 
Acid. 
51 
66 
I32 
IO4 
VIII. 
^ .do. 
.do. 
29 
61 
234 
IOO 
IX. 
...do. 
Iron. 
Neutral, ferrous sul¬ 
54 
66 
182 
102 
phate. 
IX. 
.. .do. 
.do. 
Acid, ferrous sul- 
57 
72 
189 
91 
( 
phate. 
X. 
Acid, ferric tartrate.. 
56 
66 
143 
97 
a Total amount of element absorbed, amount absorbed per gram of roots, and root to top ratio, each taken 
as ioo for plants with all roots in complete solution. Corresponding values for plants with part of roots in 
complete solution expressed relative to ioo. 
The amount of nitrogen or phosphorus absorbed by plants with half 
their roots in the complete solution was 0.76 of that absorbed by plants 
with all their roots in the complete solution, while the similar figure for 
potassium and iron was 0.66. As already pointed out, it was to be 
expected that a somewhat different figure would be obtained for potassium 
than for nitrogen and phosphorus, as a lack of potassium can be supple¬ 
mented to some extent by an abundance of sodium. The lower figure 
for iron may be connected with the immobility of iron in the plant (4). 
The less absorption of an element supplied to only part of the roots of 
a plant was not due to the partial plants having a smaller absolute amount 
of the element available than the complete plants. This was proved by 
the results of Experiments III and V, where doubling the quantity of 
nitrogen or phosphorus in the solution supplied to half the roots did not 
appreciably increase the amounts of nitrogen or phosphorus absorbed by 
these plants. 
It is apparent that the fewer roots in the complete solution the less 
nearly the plants reached the optimum absorption. The decrease from 
the optimum absorption was not, however, directly proportional to the 
portion of roots in the complete solution. The relation between the 
portion of roots in the complete solution and the fraction of the maximum 
amount of nitrogen absorbed is shown by the curve in figure 1. 
