14 New Hampshire Experiment Station [Bulletin 239 



Seed 



The amount of seed used varied from as little as twelve bushels 

 to as much as twenty-two. No influence on yield for 1927 was 

 noticeable in the northern group, but all through the southern part 

 of the state the amount of seed was closely associated with yield. 

 An increase in seed resulted in an increase in yield. (Table 

 X.) On the basis of increases in yield and decreasing costs per 

 bushel it is probably unwise under present systems of culture to use 

 more than 18 to 20 bushels of seed per acre. When small amounts 

 of seed (12 to 13 bushels) were used one bushel increases in seed 

 reduced cost per bushel 12 to 15 cents. When the larger amounts 

 of seed (18 bushels) were used the same increases in seed reduced 

 cost per bushel 3 to 4 cents. 



The other cultural practices remained practically the same. 

 Insofar as the limited data will permit one to judge, the influences 

 due to other practices, such as spraying and fertilizing, certified 

 seed, and differences in area have been reduced to a minimum, so 

 that differences in yield are largely due to differences in the amount 

 of seed. 



Here again, in the southern part of the state, increases in 

 amount of seed gave greater returns per dollar invested than did 

 increases in amounts of fertilizer. 



In 1926 the number of growers in the north using certified 

 seed was too small to be tabulated. In the southern part of the 

 state the dry weather lessened the difference that might be found, 

 yet the ten bushels average increase more than paid for the higher 

 seed cost at the prices prevailing for the 1926 crop. In 1927 in- 

 creases of from 40 to 50 bushels recorded in all three groups much 

 more than paid for the extra seed cost. (Table XI.) 



Certified seed is also more important in the southern part of 

 the state than in the north. Better seed gave greater returns per 

 dollar invested than did increases in fertilizer. 



Method of Applying Fertilizer 



Two common methods used to fertilize the potato crop were: 

 (a) to put all fertilizer on at planting time, and (b) to put on part 

 at planting time and the balance before the first cultivation. Yields 

 did not indicate that the latter practice is justifiable even when as 

 much as 2,500 pounds were applied. This is particularly true in 

 years of moderate amounts of rainfall. Hardenburg<^> found that 

 under usual conditions in New York State broadcasting part of the 

 fertilizer before planting gave some increase in yield. It is doubt- 

 ful, however, if the increase in yield due to a double application 

 is sufficient to pay for more than the additional labor. 



In Coos and Grafton Counties a slight increase in yield fol- 

 lowed the two applications method. In the rest of the state, prob- 

 ably because of the dry season of 1926, a materially smaller yield 

 was obtained from the same practice. (Table XII.) 



Labor costs per acre and per bushel were higher when two ap- 

 plications were made. Cost per bushel in the north was the same. 



