10 



BULLETIN 1014, U. S. DEPARTMENT OF AGRICULTURE. 



the vicinity of Washington, and this gain in time of maturity does 

 not represent the gain of early over normal seedings. In this con- 

 nection, some comparisons of early seedings made in April with 

 seedings made at more nearly the normal date of seeding (May 1 to 

 15) will be of interest. 



Table 4. — Differences in the dates of seeding and the resulting differences in the dates 

 of emergence, silking, and ripening of corn in experiments conducted at the Arlington 

 Experimental Farm, near Washington, D. C, during the 6-year period from 1915 to 

 1920, inclusive. 





Seedings com- 

 pared. 



Years of data. 



Number of days difference in — 



Average dates 

 of seeding. 



Seedings. 



Emer- 

 gence. 



Appear- 

 ance of 

 first silks. 



Ripening. 



Apr.18 



[•April and May . . 

 [■May and June. . . 

 SJune and July. . . 



1915. 1916. 1917, and 1920. . 

 1915, 1917, and 1920 



1915. 1917. 1918, and 1920. . . 



32 

 33 



28 



25 

 30 

 27 



14 



22 

 26 





May20 



May 20 



14 



June22 



23 















Data from such comparisons made in 1917, 1919, and 1920 are 

 shown in Table 5. In 1917 the experimental plats were located on 

 fairly uniform upland. The seeding made on April 12 was on land 

 that had been cropped to soy beans the previous year, followed by 

 rye that had been plowed under preparatory to seeding corn. The 

 plat seeded on May 14 was on land that had been in sod the previous 

 year. The two plats, however, were sufficiently similar to permit 

 reliable comparisons in respect to the characters dealt with in Table 

 5. In 1919 and 1920 all the seedings were made in adjacent or 

 neighboring plats on uniform reclaimed river land that had been 

 previously cropped to corn. 



The results presented in Table 5 show that in the season of 1917 

 plants from seedings made a month earlier than normal were about a 

 week earlier in silking than plants from normal seedings. In 1919 

 the gain in earliness was less than a week. In 1920 a difference of 17 

 days between seedings resulted in a gain of 7 to 9 days in the time of 

 silking. The differences in the time of silking correspond fairly 

 closely with the differences in the time of ripening and can be deter- 

 mined more readily and with a greater degree of accuracy. The data 

 available indicate that the differences at the time of ripening are 

 slightly less than at the time of silking. 



