276 
IOWA ACADEMY 02 SCIENCE Voe. XXIX, 1922 
FIELD EXPERIMENT NO. i 
Ground plowed before seeding; corn planted June 10; no culti- 
vation; weeds allowed to grow. Measurements and collections 
made August 8. Data given in Table 3. 
TABLE 3 
CORN — NO CULTIVATION 
Soil moisture 18.7 per cent 
Designation 
No. or 
PLANTS 
Aver. 
Height 
cm. 
Green 
Weight 
gm. 
Amount 
Wa'.'kr Giv- 
en Off for 
Growing 
Season gms. 
Corn-stalks very slender. Leaves 
light yellow in color 
2 
71 
Polygonum pennsylvanicum 
(ripe seed) 
10 
122 
1,160 
82,636.08 
Polygonum persicaria 
(seed almost ripe) 
4 
71 
175 
12,466.65 
Polygonum convolvulus (seed ripe) 
4 
244 
153 
10,899.41 
Convolvulus sepium (bloom) 
1 
391 
32 
2,279.62 
Oxalis strict a (seed ripe) 
3 
12 
8 
356.19 
Amaranthus retro plexus (bloom) 
6 
10 
5 
569.90 
Setaria glauca (seed ripe) 
1 
79 
19 
1,353.53 
Setaria viridis (not headed) 
202 
48 
740 
52,716.12 
Panicum capillare 
6 
48 
21 
1,496.50 
Total for all weeds 
237 
. 2,313 
164,774.00 
FIELD EXPERIMENT NO. 2 
Ground plowed before seeding; corn planted June 10, weeds 
removed for a distance of a radius of 30 cm. from hill ; later 
allowed to grow. Weeds cut off at ground by hoe July 13. 
Measurements and collections made August 16. Data for the 
partial cultivation are given in table 4. 
TABLE 4 
CORN — PARTIAL CULTIVATION 
Soil moisture 14.6 per cent 
Designation 
No. OF 
Peants 
Aver. 
Height 
cm. 
Green 
Weight 
gm. 
Am mint 
Water Giv- 
en Off for 
Growing 
Season gms. 
Corn-stalks slender and light yellow 
in color 
3 
91 
Polygonum persicaria (seed ripe) 
25 
43 
450.0 
32; 057.10 
Cheno podium album (seed ripe) 
2 
58 
30.0 
2,137.14 
Portulaca oleracea 
3 
52 
1.5 
106.76 
Setaria glauca (seed ripe) 
23 
61 
164.0 
11,683.03 
Setaria viridis 
95 
40 
200.0 
14,247.60 
Echinochloa crusgalli (seed ripe) 
20 
63 
139.0 
9,901.98 
Panicum capillare 
3 
31 
5.0 
356.19 
Total for all weeds 
171 
989.5 
70,489.80 
