18 BULLETIN 618, U. S. DEPARTMENT OF AGRICULTURE. 
also at stations in some of the Eastern and Southern States. These 
tests have all been of short duration. The principal ones were con- 
ducted at Madison, Wis.; DeKalb, 111. ; Arlington Farm, at Rosslyn, 
Va. ; Statesville, N. C; and Athens, Ashburn, and Quitman, Ga. 
At Madison, Wis., and De Kalb, 111., durum varieties were found 
not adapted and were discarded because of poor quality of grain or 
low yields. At the stations in the Eastern and Southern States the 
durum varieties were grown with the winter wheats adapted to those 
sections. Fair yields were obtained from durum varieties when fall 
sown, but all were low in comparison with the yields of the common 
wheats. 
In general, the altitude in the Prairie States increases and the 
precipitation decreases from east to west. The altitude varies from 
600 to 1,600 feet, in round numbers. The average annual rainfall 
at these stations varies from 32.6 to 20.5 inches. The three stations 
having the lowest rainfall are located in the valleys of the Sioux 
and Red Rivers near the Minnesota-Dakota boundary. Properly 
speaking, these valleys are the only portions of this section that can 
be called subhumid. Most of the remainder would be better desig- 
nated as humid, although the eastern portions of Nebraska and 
Kansas might easily be placed as either subhumid or humid territory. 
The annual rainfall usually is sufficient for normal crop produc- 
tion. Nearly half of it falls during the four summer months, from 
May to August, inclusive. The growing season is fairly long, varying 
from about 130 to more than 150 days. 
Figure 8 shows, by means of graduated columns, the average 
yield of the best durum-wheat variety and of the leading variety in 
each of several groups of common wheat in varying periods of years 
at the nine stations. The same data will be found in tabulated 
form in Tables III to XI, inclusive. 
Figure 9 shows heads of five varieties of wheat, one durum and 
four common, each representative of a group important in the prairie 
section and in the Great Plains area. 
RESULTS AT M'PHERSON, KANS. 
As shown in Table II (page 15), McPherson is located on a deep 
sandy loam at an altitude of almost 1,500 feet. The average precipi- 
tation has been 31.2 inches in a 26-year period. The experiments 
at McPherson were conducted in cooperation with the Kansas Agri- 
cultural Experiment Station. The results are shown in Table III 
and graphically in figure 8. 
Durum varieties were under experiment for six years, though in 
one year, 1908, the records of the yields of all varieties but one were 
lost. Since McPherson is located outside of the spring-wheat belt, 
no spring varieties of common wheat were grown. Hard red winter 
wheats of the Crimean group, such as Crimean, Kharkof , and Turkey, 
