10 BULLETIN 157, U. S. DEPARTMENT OF AGRICULTURE. 



YIELD OF GRAIN. 



The annual and average yields of winter wheat in bushels per acre 

 from 1910 to 1913, inclusive, are presented in Table III and are com- 

 pared graphically in figure 4. 



Table III. — Annual and average yields of winter wheat from fall-plowed and spring- 

 plowed plats at the Nephi substation, 1910 to 1913, inclusive. 



Yield per acre of grain (bushels). 



Average. 



Plowed in spring previous to seeding . 

 Plowed in fall one year before seeding. 



18.5 

 16.8 



The yields reported in Table III agree fairly with the moisture data 

 reported in Table II. The average difference in yield of 1.7 bushels 



WELD W BUSHELS PER ACRE 

 O 2 4 6 3 /O /2 /* /6 /3 20 22 24 26 28 30 32 34 



^@^^^^^^^^^^m 



EXPLAAf/ITltpA/- 

 SF>fi/XG p\jOW//%5 

 FALL 



Pig. 4. — Diagram comparing the annual and average yields obtained in the spring-plowing and fall- 

 plowing tests at the Nephi substation, 1910 to 1913, inclusive. 



per acre favors spring plowing, which has given yields equal to or 

 greater than fall plowing each year since the experiment began. 

 This small difference in yield, however, is not so important in itself 

 as it is when considered jointly with the cost of production. 



RELATIVE COST OF FALL AND SPRING PLOWING. 



Fall plowing is more difficult than spring plowing, and for this 

 reason it generally costs more. The difference in cost at the substa- 

 tion has varied between 15 and 25 cents an acre, with an average of 

 20 cents. In addition to this, it has been observed that the plats 

 which were spring plowed were more nearly free from weeds and 

 volunteer grain during the fallow period than the plats plowed in the 

 fall. It was always necessary to replow or double disk the fall- 

 plowed plats in the spring, oyving to a rather vigorous growth of weeds 

 and volunteer grain. Even these operations often failed to destroy 



