8 4 6 
Journal of Agricultural Research voi. xxvn, no. h 
Table I. —Summary of the climatic conditions at Manhattan, Kans., for the growing 
season of 1920 
Month. 
Days 
(inclusive). 
Air temperature (° F.). 
Precipi¬ 
tation. 
1 
Evapora¬ 
tion from 
freewater 
surface. 
Average of— 
Maxi¬ 
mum. 
Mini¬ 
mum. 
Mean. 
Maxi¬ 
mum. 
Mini¬ 
mum. 
Inches . 
Inches. 
May... 
i -5 
61 
71 
51 
74 
42 
O. 568 
Do. 
6-10 
61 
73 
50 
83 
46 
O. 64 
• 783 
Do. 
11-15 
59 
68 
51 
81 
40 
• 2 5 
• 713 
Do. 
16-20 
61 
72 
51 
85 
45 
. 04 
• 591 
Do. 
21-25 
70 
79 
6l 
88 
47 
.48 
. 801 
Do. 
25-31 
69 
79 
58 
92 
54 
• 17 
. 8lO 
June. 
i -5 
65 
77 
54 
82 
40 
•34 
I. 077 
Do. 
6-10 
78 
90 
67 
98 
58 
I. 405 
Do. 
11-15 
84 
96 
73 
99 
72 
I. 983 
Do. 
16-20 
68 
78 
59 
9 i 
55 
.04 
I- 253 
Do. 
21-25 
70 
87 
55 
90 
47 
.76 
1.418 
Do. 
26-30 
84 
79 
61 
98 
69 
.82 
I. 776 
July 
i -5 
83 
96 
70 
100 
61 
. 02 
i- 339 
Do. 
6-10 
7 i 
85 
57 
89 
54 
• 15 
1. 422 
Do. 
n-15 
77 
90 
65 
95 
55 
I. 02 
1. 520 
Do. 
16-20 
79 
93 
65 
97 
61 
1. 290 
Do. 
21-25 
82 
97 
67 
105 
63 
i* 725 
Do. 
26-31 
72 
85 
59 
94 
5 i 
3-64 
i- 143 
August. 
i -5 
74 
86 
63 
90 
58 
1.128 
Do. 
6-10 
79 
94 
61 
96 
57 
1.080 
Do. 
11-15 
70 
84 
56 
90 
47 
. 12 
1. 232 
Do. 
16-20 
7 i 
87 
53 
9 i 
48 
5. 18 
.857 
Do. 
21-25 
68 
79 
58 
85 
5 i 
1. 172 
Do. 
26-31 
73 
84 
62 
92 
56 
.87 
1. 306 
COLLECTION AND PREPARATION OF MATERIAL 
STEMS, LEAVES, AND GRAIN 
Five plants were selected and harvested on September 2, when the 
grains were in the late-dough stage and were well glazed and dented 
(PI. i, A). At this stage of development it was thought that the plants 
had removed from the soil most of the minerals of which they were 
capable, although there would probably be some slight rearrangement 
of materials in the various plant parts before full maturity. Further¬ 
more, at this stage the leaves were all attached to the plants (PI. i, B) 
and green, so that little or no material had been lost from them by leach¬ 
ing. It is worthy of note that a gentle rain fell during the night of 
September i, so that the leaves and stems were especially free from 
any adhering dirt when they were harvested. The plants were cut off 
at the surface of the ground and their green weight at once determined. 
A general description of each of the five plants at the time of harvesting 
is given in Table II. 
As soon as the green weight of each plant was determined, the stem, 
leaves, and grain were separated, ground or cut into convenient pieces, 
and placed in a hot air drying oven at 105 ° C. for 24 hours. The material 
was then transferred to glass jars and sealed until it was ready to be 
