76 
Journal of Agricultural Research 
Vol. IX, No. 3 
Table III .—Nitrogen and phosphoric acid absorbed by rice in Experiment I 
Flask No. 
Nitrogen 
(N) in dry 
stalks and 
leaves. 
Nitrogen (N) in dry 
roots. 
Nitrogen 
(N) ab¬ 
sorbed by 
12 plants. 
Nitrogen 
(N) ab¬ 
sorbed per 
gram of 
roots. 
Phos¬ 
phoric 
acid 
(P2O5) in 
dry stalks 
and 
leaves. 
A-flasks- 
B-flasks. 
I-18 
19-36 
49-54 
Per cent. 
1. 32 
3 - 90 
4.40 
Per cent. 
0. 97 
1. 47 
2. 41 
Per cent. 
O. 97 
2 . 12 
2. 41 
Gm. 
Gm. 
Per cent. 
0.5138 
. 6631 
O. 226 
. 156 
I. 61 
I- 54 
If the plants with all their roots in the complete solution are con¬ 
sidered as normal in growth and nitrogen content, it is evident that the 
plants partially supplied with nitrogen made slightly less than normal 
growth, had 23 per cent greater ratio of roots to tops, 1 and absorbed 0.77 
of the normal amount of nitrogen. The influence of the need of the 
plant on the selective absorption of nitrogen is shown by the amount of 
nitrogen absorbed per gram of roots, the partial-nitrogen plants having 
absorbed 1.45 times as much nitrogen as the normal plants. 
EXPERIMENT II.—CORN WITH HALF THE ROOTS IN NITROGEN-FREE 
SOLUTION 
It was thought desirable to repeat the preceding test with corn, so that 
the results might not be taken as being peculiar to rice alone. Because 
of the rapid growth, com could be grown for 21 days only instead of 40, 
with the means at our disposal. 
No-nitrogen plants were grown in 200-c. c. flasks for the 21 days; all 
others in 200-c. c. flasks for 11 days, 500-c. c. flasks for 4 days, and 
1,000-c. c. flasks for 6 days. The nutrient solutions used were the same 
as in Experiment I, and were changed six times during the experiment. 
Eight flasks were taken as a unit and the units duplicated for each treat¬ 
ment. Experimental data are given in Tables IV and V. 
Table IV .—Growth of corn in Experiment II 
Nutrient solution. 
Flask 
No. 
Weight of stalks 
and leaves. 
Number of 
roots. 
Average oven- 
dry weight 
of roots. 
Ratio 
of 
roots 
to 
tops. 
A-flasks. 
B-flasks. 
Green. 
Oven- 
dry. 
Av¬ 
erage 
oven- 
dry. 
A- 
flasks. 
B- 
flasks. 
A- 
flasks- 
B- 
flasks. 
Nitrogen-free. 
Nitrogen-free. 
f 1-8 
\ 9“ 16 
/17-24 
\ 2 S *32 
/ 33“40 
\41-48 
Gm. 
12.4 
15*2 
184.0 
191*5 
270. 0 
255-0 
Gm. 
1-55 
2.27 
14.71 
15 - 78 
21. 92 
19. 26 
Gm. 
} i* 91 
} I 5 - 25 
Jao. 59 
/ 37 
l 38 
/ 67 
1 69 
/ 77 
t 76 
46 
37 
72 
62 
87 
84 
Gm. 
} 0.80 
}r. 5 i 
} 1-87 
Gm. 
o.71 
1.94 
1.92 
0.791 
. 226 
. 184 
Do . 
Complete. 
Complete. 
.do. 
1 The ratio of roots to tops is taken as the weight of dry roots divided by the weight of dry stalks and 
leaves. 
