2 BULLETIN 991, U. S. DEPARTMENT OF AGRICULTURE. 
in more typical dry- farming territory farther west. Though the 
results at Edgeley are in general agreement with those of the other 
stations, they differ from them in some respects in that they are 
expressive of conditions in a transition zone between the dry and 
the humid areas. 
The first crops in these cooperative investigations at the Edgeley 
substation were planted in 1906. As more land became available the 
work was increased in 1907 and again in 1908. To check on deeper 
soil the results obtained at the station farm a 40-acre tract about 1 
mile distant was leased and experimental work started on it in 1916. 
In the following pages this tract is referred to as section 9 and the 
plats on the station farm as the main field. 
In interpreting the results of these investigations the writer has 
been greatly aided by his knowledge of the results obtained from the 
closely coordinated investigations conducted by the Office of Dry- 
Land Agriculture Investigations at 23 other stations on the Great 
Plains and by the reports, comments, and suggestions of the men in 
charge of such investigations at their respective stations. The fol- 
lowing discussions and conclusions are therefore submitted with a 
higher degree of confidence than they would be were they based 
entirely upon investigations conducted at a single isolated station by 
an individual investigator. 
SOIL. 
The soil on which the main field is located is derived from the de- 
composition of shale. Shale in undecomposed particles is found very 
near the surface. In the third foot the shale, while broken and offer- 
ing fairly free passage to water, is not broken down into soil. The 
depth of feeding of crops is practically limited to the first 2 feet. 
The first foot carries an exceptionally large proportion of water 
available to the crop and retains about 31 per cent of its dry weight 
of water, but about 14 per cent is nonavailable to the crop. The sec- 
ond foot retains about 28 per cent of its weight of water, but 18 per 
cent is nonavailable. The third foot retains about 32 per cent of 
water, but about 28 per cent is nonavailable. Thus it is possible to 
store in the first foot about 17 per cent of available water, in the 
second foot 10 per cent, and in the third foot about 4 per cent. Trans- 
lated into inches of water, this amounts to a total of 4.76 inches, bas- 
ing the calculation on an estimated soil weight of 80 pounds per 
cubic foot. While the amount of available water that can be stored 
in the first foot is exceptionally high, the shallowness of the soil re- 
duces its total storage capacity to about one-half that of deeper soils. 
The soil of section 9 (the tract used as a check in these investiga- 
tions) is a deep clay loam of greater water-storage capacity. 
