14 Nebraska Agricultural Exp. Station, Research Bui. 13 
ERROR DUE TO COMPETITION BETWEEN ADJACENT PLATS 
It is a well known principle in ecology that a keen com- 
petition for soil moisture and nutrients may exist between 
plants which differ in growth habit, when grown in close 
proximity. Competition between adjacent rows of different 
varieties, selections, or rates of planting, had suggested 
itself as a possible source of error in crop tests. An inves- 
tigation was planned in 1912 to determine the relative merits 
of rows and blocks for making comparative yield tests in the 
small grain nursery and in corn experiments. 
The question was: Will two varieties give the same com- 
parative yields when planted in alternating rows as when 
planted in alternating blocks consisting of a number of rows? 
It was reasonable to assume that there would be less plat- 
competition between varieties planted in blocks than when 
planted in single rows. 
It has been a common practice in crop breeding experi- 
ments to compare the selected strains in adjacent one-row 
plats for a number of years. Many other comparative tests 
have also been made in single row plats. 
ILLUSTRATION OF PRINCIPLE OF C03IPETITI01V BETWEEN 
ADJACENT ROWS 
On the right-hand side of Fig. 1 is shown a crop of Tur- 
key Red winter wheat planted in the fall of 1912. To the 
south of this was planted Scotch Fife spring wheat in the 
spring of 1913. The first row of spring wheat, spaced ten 
inches from the winter wheat, is seen to have grown only 
about four inches tall with no grain production. The sec- 
ond row of spring wheat made an almost normal growth, 
while the third row was entirely normal. The complete fail- 
ure of the first row of spring wheat may be accounted for 
by the shortage of both moisture and available plant food 
material, due to the more rapid and luxuriant growth of the 
adjacent winter wheat. While this is an extreme example of 
competition between adjacent rows, it illustrates a principle 
commonly applying in crop yield tests. 
COMPETITION BETWEEN ADJACENT ROWS OF S3IAL.L, GRAIN 
The plan of the experiment was to plant two crops under 
comparison in alternating one-row plats and alternating five- 
row plats. These were replicated 50 times each year in order 
