EXPERIMENTS IN FIELD PLOT TECHNIC 



33 



in the order named in four distributed sections of the field. The aver- 

 age yields of these varieties in the four series, in bushels per acre, for 

 border rows and for interior rows, are shown below, together with 

 the average dates of heading, dates of maturity, and heights, also de- 

 termined for the four series. 



* Dates of heading and maturity are the numbers of days after April 30. Thus 1 is 

 May 1, 32 is June 1, 47 is June 16, etc. 



Now dividing the yields in border rows by the yields of the same 

 varieties in interior rows, we obtain the relative border yields, which 

 are substituted in the table below for the border yields in bushels. 

 To determine the degree of competition between the varieties Fultz and 

 Michigan Amber we divide the larger relative border yield (107) by the 

 smaller (89) and subtract 100, giving 20 per cent. Since in this case the 

 relative border yield of the variety on the left is higher, the difference is 

 given a minus sign. Similarly a value of +12 per cent is obtained for 

 the competition between Michigan Amber and Michigan Wonder No. 

 211. These figures mean that the relative border yield of Fultz ex- 

 ceeded that of Michigan Amber by 20 per cent in their competing 

 border rows, while that of Michigan Wonder exceeded that of Michi- 

 gan Amber by 12 per cent. 



The relative yields of these varieties are obtained similarly, 

 in the first case by dividing 14.9 by 12.2 (+22%) and in the second 

 case by dividing 18.1 by 14.9 (+21%). Both values are positive be- 

 cause in each case the yield of the variety on the left is higher than 

 that of the variety on the right. The difference in dates of heading, 

 maturity, and height are obtained simply by subtraction, being positive 

 when the value of the variety on the right is greater and negative when 



