78 Nebraska Agricultural Exp. Station, Research Bui. 13 
A comparison of the Hogue's Yellow Dent ear-to-row-selec- 
tion with the original unselected Hogue's Yellow Dent corn 
for the seven-year period 1909-1915 — during which time the 
precaution was taken to have strictly comparable results by 
thinning to a uniform stand, and to reduce error by several 
replications — indicates an increased yield of only six-tenths 
of one per cent due to the breeding. 
In order to measure progress in the improvement of corn 
thru breeding, it is necessary to compare the results each 
year with the original unselected corn. 
SOIL LIAIITATIOX AS A SOI RCE OF ERROR 
IX POT EXPERIMENTS 
The past discussions in this bulletin have dealt entirely 
with field experiments. Extensive use has also been made of 
pots filled with soil for comparing the yields of various crops 
and soil types, and for determining the fertilizer needs of dif- 
ferent soils and the water requirement of crops. A review of 
the literature indicates a marked lack of uniformity in the 
size of pots and rate of planting in them. 
Tables 37 to 47 contain the results from experiments con- 
ducted during three years, 1913-1915, bearing upon the effect 
of the size and rate of planting as sources of experimental 
error in pot tests. 
Galvanized iron pots were used, having a constant water 
supply from jars connected at the bottom. Rain was excluded 
by means of a closefitting cover about the stalk, and surface 
evaporation was reduced by means of a three-inch layer of 
gravel. All pots were planted each year from the same ear 
of Hogue's Yellow Dent corn. Suckers were removed as soon 
Table 37 — Summary shotving the effect of the size of the pot 
upon the aroivth of corn. Hogue's Yelloiv Dent corn 
(1913) 
Size of 
pot 
Wt. of 
soil 
(moisture- 
free) 
No. of 
pots 
averaged 
Dry matter 
Ear Total 
Total 
leaf-area 
per plant 
Height of 
stalk 
Inches 
Pounds 
Grams 
Grams 
Sq. in. 
Inches 
12x24. . . 
86 
4 
28 
165 
680 
71 
16x36. . . 
245 
80 
194 
416 
1070 
89 
30x36... 
933 
4 
311 
599 
1440 
83 
