8 o 
Journal of Agricultural Research 
Vol. IX, No. 3 
nitrogen and the greater is the amount of nitrogen absorbed per gram of 
roots. 
EXPERIMENT V.—RICE WITH ONE-HALF THE ROOTS IN A PHOSPHORUS- 
FREE SOLUTION 
The previous experiments yielded pretty definite figures for the rela¬ 
tive amounts and rates of nitrogen absorption for plants partially and 
completely supplied with nitrogen. It was therefore of interest to see 
whether the same figures would hold for the absorption of other mineral 
elements under like conditions. In this experiment the absorption of 
phosphorus was tested. 
The complete neutral nutrient solution was used with ferric citrate as 
the source of iron. The double-phosphorus solution was the same as 
the complete, except the quantities of both dipotassium phosphate 
(K 2 HP 0 4 ) and monopotassium phosphate (KH 2 P 0 4 ) were doubled. The 
no-phosphate plants were grown in 200-c. c. flasks for 40 days; all others 
in 200-c. c. flasks for 26 days, and in 500-c. c. flasks for 14 days. Eight 
flasks were taken as a unit and the units duplicated for each treatment. 
The solutions were changed nine times during the experiment. Experi¬ 
mental data are given in Tables X and XI. 
Table; X. —Growth of rice in Experiment V 
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. 
Phosphorus-free .. 
Do. 
Phosphorus-free.. 
Complete. 
f i- 8 
\ 9-16 
/17-24 
\ 2 5 " 3 2 
J33 -40 
l 4 i “48 
149-56 
157-64 
/ 6 s -72 
\ 73 - 8 o 
Gm. 
6.03 
6.11 
192.86 
195.01 
208. 37 
186.44 
202.36 
192.20 
181. 78 
189.34 
Gm. 
1.96 
1.94 
3 °. 2 5 
30. 26 
30. 87 
28. 19 
29-95 
28. 72 
2 7 - 33 
28. 85 
Gm. 
} i -95 
J3°* 26 
} 2 9 * 53 
r 2 9*34 
>28.09 
f 120 
\ 129 
/ 312 
l 307 
/ 297 
\ 281 
/ 294 
l 264 
/ 237 
l 250 
127 
139 
286 
292 
256 
258 
258 
267 
236 
247 
Gm. 
} 0-56 
} 4-80 
} 4 - 2 $ 
} 3-72 
} 3-44 
Gm, 
0. 74 
4-32 
4:14 
3-54 
3-54 
0. 666 
*30i 
. 284 
.247 
. 248 
Do. 
fComplete double 
\ phosphorus. 
Complete. 
Complete. 
Complete double 
phosphorus. 
Complete double 
phosphorus. 
Table XI. —Phosphoric acid and nitrogen absorbed by rice in Experiment V 
| Phosphoric acid (P 2 Os). 
Nitrogen 
(N) in dry 
stalks and 
leaves. 
Flask No. 
In dry 
leaves and 
stalks. 
Absorbed 
by 16 
plants. 
Absorbed 
per gram 
of roots. 
I-i6 
Per cent. 
O. 17 
I- 13 
Gm. 
Gm. 
Per cent. 
17-32 
O. 3386 
O. 0784 
4 - 13 
33~48 
I. 19 
• 3481 
. 0841 
4. 18 
' 49^4 
S 3 
• 445 6 
. 0614 
4 - 43 
65-80 
I- 53 
. 
. 4265 
i 
.0611 
4. 12 
