A STUDY OF FACTORS INFLUENCING THE YIELD OF POTATOES 1253 



not apply to the growers who used more seed. Furthermore, since the 

 group of growers using less than 12 bushels of seed per acre included those 

 who planted in checkrows, it was doubtless possible to control weeds 

 with fewer cultivations than were necessary for fields planted in drills. 

 A fairly consistent positive influence of frequency of cultivation on yield, 

 irrespective of the value of manure and fertilizer used, is shown in table 

 80. It is evident that the highest frequencies of cultivation were pro- 

 ductive of profitably increased yields except for the few growers who, 

 because of checkrow planting which made cross cultivation possible, were 

 able to control the weeds with fewer cultivations. The coefficient 0.169 

 d= 0.038 (fig. 147), while small, is positive and is significant in value. 



s 



Yield per acre, in bushels 



8 S K 8 8 



3 



21 



52 



60 



64 



36 



27 



19 



5 



6 



3 







1 



1 



1 







1 



1 7 38 70 50 61 34 24 8 4 1 1 1 300 

 r = 0.169 0.038 



FlG. 147. CORRELATION OF FREQUENCY OF CULTIVATION AND YIELD ON 300 MONROE COUNTY 



FARMS IN 1913 



Frequency of cultivation in Franklin and Clinton Counties 

 Cultivation in Franklin and Clinton Counties is not generally continued 

 as late in the growing season as in most other regions of the State. On 

 the other hand, ridging is begun early in the season and the crop is given the 

 final ridging soon after blossoming. The average number of cultivations 

 in this region in 1913 was 6.3. As shown in table 15, this was the only 

 region of the four in which a very significant proportion of the total acreage 



