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. 



