Experimental Error in Crop Tests 
27 
These 80 strains are now all being grown in five-row 
plats, replicated ten times, for the purpose of establishing 
the correct relative yields, free from competition as a source 
of experimental error. Single-row plats are now regarded 
as unreliable and misleading, because a strain is certain to 
be unduly favored when grown beside a strain lower in com- 
petitive qualities due to such factors as low stooling, slow 
growing, or partial winterkilling. It is important to have 
any crop being tested surrounded by a crop of its own kind. 
COMPKTITION BETWEKN INDIA IDl AL PLANTS 
Altho the yields of small grain are never compared by 
planting alternating seeds of two varieties or two grades of 
seed in the same row, yet such a comparison may be of inter- 
est to throw further light upon the principle of competition. 
Table 9 — Relative yields, at the normal field rate of planting, 
of equal numbers of large and small ivheat seeds when 
grown alone in blocks and. when grown in competition by 
alternation in the same roiv^ 
Method of comparing large and small 
seeds 
Ratio of yield of small seeds to 
large seeds 
Grain 
WINTER WHEAT, 1914 
! 90:100 
61:100 
WINTER WHEAT, 1915 
I 99:100 
Grades competing I 83:100 
SPRING WHEAT, 1914 
Grades alone in blocks 
Grades competing 
Grades alone in blocks. 
Grades alone in blocks. 
88:100 
Grades competing | 78:100 
SPRING WHEAT, 1915 
Grades alone in blocks . 
Grades competing 
80:100 
82:100 
Straw 
94:100 
72:100 
98:100 
78:100 
93:100 
78:100 
93:100 
73:100 
Total 
94:100 
71:100 
98:100 
79:100 
92:100 
78:100 
90:100 
75:100 
AVERAGE FOR WINTER AND SPRING WHEAT, 1914-1915 
Grades alone in blocks 
89:100 
94:100 
93:100 
Grades competing 
1 76:100 
75:100 
76:100 
Compiled from data in Nebraska Research Bulletin No. 11, 1917. 
