A STUDY OF FACTORS INFLUENCING THE YIELD OF POTATOES 1227 



a tendency among the growers who planted the most seed to use also 

 somewhat more than the average value of manure and fertilizer. Also, 

 there was more spraying for blight among these growers. However, the 

 same marked influence on the yield from the rate of planting is shown in 

 table 24, under the discussion of manure and fertilizer,' where each of these 

 factors is treated under the various subheads. The single discrepancy in 

 table 59, in the group of growers using from 11 to 12 bushels of seed, is 

 due, at least in part, to the larger value of manure and fertilizer used by 

 this group. Since the average number of eyes per piece gradually in- 

 creased from the lowest to the highest rate of planting, it may be con- 

 cluded that the rate of planting varied not so much according to closeness 

 of planting as according to size of seed pieces used. From table 59, it 

 is apparent that the growers in this region who used as high as 15 bushels 

 of seed per acre in 1912, did not use more than was profitable. Applying 

 the biometrical measure of correlation of this factor with yield (fig. 140) 

 shows the significant coefficient 0.275 db 0.034. 



Rate of planting in Steuben County 



In the four regions surveyed, Steuben County growers used the least 

 seed, planting an average of only 10.1 bushels per acre in 1912 (table 60). 

 The highest rate reported by any of the 360 growers was 18 bushels, and 



TABLE 60. RELATION OF RATE OF PLANTING TO YIELD ON 360 STEUBEN COUNTY FARMS 



IN 1912 



there was a profitable increase in yield from every increase of 2 bushels 

 per acre planted, up to 18 bushels. Steuben County growers did not 

 exceed the optimum rate of planting in 1912, and it is safe to recommend a 

 considerable increase in the average amount of seed used in that region. 



