Experimental Error in Crop Tests 
29 
three inside rows of five-row blocks. The results in Table 
10 indicate marked competition between varieties. Variety 
competition amounted to 61 per cent and 46 per cent for win- 
ter wheat yields in 1914 and 1915 respectively. For spring 
wheat this competition equaled 19 per cent and 4 per cent 
in 1914 and 1915 respectively. 
COMPETITION BETWEEN CORN TEST PLATS AS A SOURCE OF 
EXPERIMENTAL ERROR 
In corn variety tests, corn breeding experiments, and 
various other corn yield tests the crops under comparison 
have customarily been planted in adjacent plats containing 
one, two, three, or four rows. The single-row plat is used 
almost universally in corn breeding experiments. In several 
instances where only three or four kinds of corn were to be 
compared, these have all been planted in the same hill, giving 
each kind of corn a definite position in the hill. This intra- 
hill method has been employed by Hartley, Brown, Kyle, and 
Zook (1912) and by Collins (1914).* 
' k .... ~ .i.. - ' 
Fig. G — Planting experimental corn plats where accuracy is required. 
Hand planters are found far superior to planting with a hoe. A 
stated number of kernels are placed in the planter for each drop 
*The year in parentheses following an author's name in the text serves 
to associate the reference with a particular publication in the Bibliography 
(pp. 91-94), where the complete title is given. 
