10 



BULLETIN 297, TJ. S. DEFAKTMENT OF AGRICULTURE. 



was May 13. The earliest frost in the autumn during this period was 

 on August 27, while the average date of the first frost was September 

 14. The average frost-free period for the six years is 123 days. 



Table VIII. — Dates of killing frosts, the last in spring and the first in autumn, with 

 temperatures recorded and length of the frost-free period for each year from 1908 to 1913, 

 inclusive, at the Belle Fourche Experiment Farm. 



[Data from the records of the Biophysical Laboratory of the Bureau of Plant Industry.] 





Last frost in 

 spring. 



First frost in 

 fall. 



Frost- 

 free 

 period. 



Year. 



Last frost in 

 spring. 



First frost in 

 fall. 



Frost- 



Year. 



Date. 



Tem- 

 pera- 

 ture. 



Date. 



Tem- 

 pera- 

 ture. 



Date. 



Tem- 

 pera- 

 ture. 



Date. 



Tem- 

 pera- 

 ture. 



free 

 period. 



1908 

 1909 

 1910 

 1911 



May 20 

 May 17 

 May 23 

 May 11 



"F. 



29 

 26 

 31 

 30 



Sept 26 

 Sept. 23 

 Aug. 25 

 Aug. 27 



°F. 

 22 

 31 

 32 

 32 



Days. 

 129 



128 

 93 

 107 



1912 

 1913 



Average . 



May 4 

 May 6 



"F. 



32 

 32 



Sept. 23 

 Sept. 24 



°F. 

 32 

 29 



Days. 

 141 

 140 



May 13 





Sept. 14 





123 



EXPERIMENTAL METHODS. 



The tests with dry-land cereals on the Belle Fourche Experiment 

 Farm have been conducted in field plats and in the nursery. In the 

 field plats varietal tests and tests of rates and dates of seeding have 

 been included. The plats have ranged from one-fiftieth to one-tenth 

 of an acre hi size. In the cereal nursery the varieties have been 

 grown in short rows. The use of the nursery has made it possible 

 to test economically a much larger number of varieties than could 

 have been grown in the field plats. Careful records have been kept 

 of the behavior of the varieties included in both the plat and nursery 

 experiments. 



PLAT EXPERIMENTS. 



The field tests have included varietal tests of winter wheat, rye, 

 and emmer and of spring wheat, oats, barley, and flax. There have 

 also been rate-of -seeding tests with spring wheat and oats and date- 

 of-seeding tests with flax and winter wheat. 



SIZE OF PLATS. 



All of the plat experiments in 1908 and 1909 and nearly all in 

 1910 were conducted on tenth-acre plats. These plats were 2 rods 

 wide by 8 rods long. They were arranged side by side in series, the 

 plats in the series being separated by 5-foot alleys. The series were 

 separated by 16.5-foot or 20-foot roads. Each plat thus had a. 

 5-foot alley along each side and a 16.5-foot or 20-foot road along 

 each end. 



Most of the tests in 1911 and all of those in 1<)12 and 1913 were 

 in plats made by sowing a, single drill width across nn S-rod series. 

 As the. drill was 6 feel wide, this gave a, plat of one-lift y-liflh of an 



