A STUDY OF FACTORS INFLUENCING, THE YIELD OF POTATOES 1165 



each other only in the number of years of successive hay crops show 

 a higher average yield of potatoes with them than with the first three. 

 This may be due to the additional residual fertilizer left from that applied to 

 the extra year of grain, or to the factor of naturally better soil as indicated 

 by the tendency to produce more grain. 



The type of rotation commonest in each region is indicated by the figures 

 in table 8 on the percentage of total crop acres occupied by each crop 

 listed. No fixed rotation is indicated, for Long Island, where potatoes are 

 grown for a varying number of successive years on the same land. The 



TABLE 8. RELATIVE IMPORTANCE OF CROPS ON FARMS SURVEYED 



figures for Steuben County indicate a rotation of potatoes, oats, hay 

 two years; those for, Monroe County, a rotation of potatoes with corn or 

 beans or cabbage, oats, wheat, hay one to two years ; and those for Franklin 

 and Clinton Counties, a rotation of potatoes with corn, oats, hay three 

 years. 



A review of the experimental literature on the influence of crop rotation 

 in potato production shows a striking preference for either grass, or a 



