A STUDY OF FACTORS INFLUENCING THE YIELD OF POTATOES 1251 



rate of planting. To further allay suspicion that the increased yields, 

 apparently due to increased cultivation, were not in part due to corre- 

 sponding increases in the value of manure and fertilizer, a study of this 

 factor in connection with value of manure and fertilizer is presented in 

 table 78. Altho comparatively few farms are involved in the study in 

 this table, the positive influence of frequency of cultivation on yield 

 is well shown. In contrast to Long Island, it is apparent that growers 

 in this region did not exceed the profitable limit in number of cultivations 

 in 1912. This statement is further proved by the coefficient of correla- 

 tion, 0.231 =t 0.034, shown in figure 146. 



Yield per acre, in bushels 



o 



1 9 

 . 10 



i H 

 I 12 



13 

 14 



15 

 S 16 



18 

 19 

 20 



2 

 11 



40 



73 



65 



69 



39 



23 



19 



8 



4 



1 



4 



1 















1 



2 5 26 64 73 78 52 38 9 10 2 1 360 

 r = 0.231 0.034 



FlG. 146. CORRELATION OF FREQUENCY OF CULTIVATION AND YIELD ON 360 STEUBEN COUNTY 



FARMS IN 1912 



Frequency of cultivation in Monroe County 



The common rotation of one to two years of cultivated crops, followed 

 by two years of grain, followed by only one to two years of hay, makes 

 the problem of weed control less of a limiting factor to yield in Monroe 

 County than in Steuben County. The growing-season rainfall for this 

 region, however, as shown in figure 127, is lower than that for the other 

 three areas, and, because of this, cultivation for moisture conservation 

 might be presumed important. The average frequency of cultivation 



