716 
Journal of Agricultural Research 
Vol. XXI, No. 10 
Table VIII.—Ph values of the culture solutions of the Tottingham series (/l) and the 
ammonium-sulphate series ( B) producing highest, medium, and lowest yields with iron 
supplied in the form of ferrous sulphate a 
Dates of solution renewals and 
growth intervals. 
Tottingham series (A) producing— 
Ammonium-sulphate series (B) 
producing— 
Highest 
yield 
(T1R3C3). 
Medium 
yield 
(T3R3C3). 
Lowest 
yield 
(T1R1C1). 
Highest 
yield 
(T5R1C1). 
Medium 
yield 
(T3R3C1). 
Lowest 
yield 
(T1R3C5). 
1920. 
Mar. 12. 
4.8 
4-7 
4.8 
4-7 
4-7 
4.8 
16. 
5-o 
4.6 
4.8 
4.4 
4.4 
4.6 
19 . 
5-3 
4.9 
5-* 
4.6 
4.4 
4-5 
23 . 
5-6 
5-2 
5-2 
4-5 
4-5 
4-5 
26. 
5-9 
5-3 
5-3 
4.4 
4.4 
4-4 
. 30 .. 
6 -3 
5-6 
5-5 
4.6 
4-5 
A • 7 
Apr. 2.. 
6.3 
5-7 
5*4 
4.6 
4.7 
4.6 
6. 
6-3 
5-6 
5-3 
4.6 
4.6 
4-7 
9 . 
6.5 
5-9 
5-7 
4.6 
4.6 
4.6 
1 3 . 
6.6 
6-3 
5*9 
4-6 
4.6 
4.7 
17 . 
6-5 
6-3 
6.0 
4.6 
4.6 
4-7 
Average. 
6.03 
5-54 
. 5-42 
4-54 
4-53 
4.60 
a The first number in each column represents the initial Ph value of the solution. 
DRY WEIGHTS OP TOPS AND ROOTS 
The relative yield values for the cultures of the two series of this exper¬ 
iment are given in Table III in connection with the relative dry-weight 
yields from the cul¬ 
tures of the preceding 
experiment. The ab¬ 
solute dry weights of 
tops and roots were 
plotted to form the 
graphs o f figures 5 
and 6, respectively. 
These graphs were 
prepared in the same 
manner as those rep- 
resenting the dry- 
weight yields in figures 
2 and 3. From the 
graphs of figures 5 
and 6 it will be ob¬ 
served that the yields 
of both tops and roots from the cultures of the Tottingham series were 
always much superior to those from the corresponding cultures of the 
ammonium-sulphate series, in which only a single culture gave a dry- 
weight yield of tops which was higher than the lowest yield of tops in 
the Tottingham series. In the ammonium-sulphate series all the root 
yields were lower than the lowest yield in the Tottingham series. 
Fig. 5.—Graphs of actual yield values of wheat tops for the Totting¬ 
ham series and the ammonium-sulphate series of experiment II. 
