SORGHUM EXPERIMENTS OX THE GREAT PLAINS. 7 
SOILS. 2 
The soils of the sorghum belt are for the most part sufficiently 
fertile to produce heavy crops of sorghum whenever there is an 
adequate rainfall. At most of these stations the soils have not been 
defined and identified; an accurate description is therefore impossible. 
At Hays, Kans., the soil is similar to the Holdrege soils in Phelps 
County, Nebr. The soil seems to be as typical a black earth, or 
chernozem, as any soil in the United States. The first 4 inches is 
MAR A PR. MAY JUNE JULY AUG. S£PT. OCT. NOV. 
.», cm co v. c\j c^ \ cm cj -^ cm ro -„ iN p; v <\J r-,> v. cm «■) s cm «0 ^ cm. c^ 
III! 1 ! Mill,.'. UJ~I I ! 
MOCCAS/N 
MONT. 
HAVRE 
MONT. 
DICKINSON 
N DAK. 
MAN DAN 
§ N.DAK 
Q> RED FIELD 
£ S.DAK. 
]J NEWELL 
<0 
5 DAK 
n ARDMORE 
CJ S.DAK. 
^ AKRON 
K COLO. 
£ HAYS 
£ KANS. 
k WOODWARD 
Q OKLA. 
■$■ LAWTON 
g OKLA. 
X CHILLICOTHE 
£ rex. 
^ AMARILLO 
TEX 
DALHART 
TEX. 
BIG SPRING 
TEX. 
TUCUMCAR/ 
NEW M EX 
Fig. 4.— Diagram showing the average frost-free periods and the earliest and the latest dates at which the 
last killing frost in the spring and the first killing frost in the fall have occurred at 16 field stations in the 
Great Plains area. The data for this diagram were obtained as follows: For Havre, Dickinson, Man- 
dan (Bismarck), Redfield, Hays, Woodward, Lawton, Chillicothe (from Quanah), Amarillo, Dalhart, 
and Big Spring, from United States Weather Bureau reports; for Moccasin, Xewell, Ardmore, and 
Akron, from the Office of Biophysical Investigations, Bureau of Plant Industry; for Tucumcari, from 
United States Weather Bureau reports for 1905 to 1912 and from New Mexico Bulletin Xo. 130 for 1913 
to 1921 (S) . 
very dark gray to black loam and the next 18 inches a slightly lighter 
colored clay loam with a highly granular structure; below this, for 8 
inches, is a gray, cloddy, heavy silty clay changing into a highly 
calcareous gray clay. 
At Chillicothe, Tex., the soil on the greater part of the present 
station consists of what the Bureau of Soils has defined as Foard clay 
loam, or at least it belongs to the Foard series. The texture is 
2 Soil descriptions were supplied by C. F. Marbut. in charge of Soil Investigations, Bureau of Soils. 
