578 



VARIOUS FERTILITY FACTORS 



more lasting profits would result. As an average of six years' 

 experiments at the Illinois Station, Professor George E. Morrow 

 produced 70.3 bushels of corn per acre with ordinary cultivation 

 (four times, or twice each way) , while eight extra cultivations in- 

 creased the yield to only 72.8 bushels. Furthermore, where no 

 cultivation whatever was practiced, the land having been well pre- 

 pared and, subsequent to planting, kept clean by clipping the weeds 

 off at the surface of the ground, the average yield for the same six 

 years was 68.3 bushels per acre. About one half of all the increase 

 from the extra cultivation during the six years was produced dur- 

 ing one especially dry season. For the other five years the extra 

 cultivation was wasted energy; and as an average the increase 

 produced was far below the cost of the extra work. 



Table 119 shows the results of more recent experiments at the 

 Illinois Station, which include the effect of plowing, preparation 

 of seed bed, cultivation, irrigation, and fertilization. 



TABLE 119. EFFECT OF SOIL PREPARATION, CULTIVATION, IRRIGATION, AND 



FERTILIZATION: ILLINOIS EXPERIMENTS 



Corn, Bushels per Acre 



In 1908 a rainfall of 10.28 inches in 30 days during the usual 

 time for corn planting necessitated very late preparation of the 

 land, and with very light rainfall during the remainder of the 

 season (only 8.93 inches between May 23 and November 22) the 



