20 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1916. 



relatively high percentage of silt and only a very small quantity of 

 coarse material, except in local spots where gravel has been brought 

 to the surface by burrowing animals. The subsoil is a grayish or 

 white silty loam. It contains a higher percentage of coarse particles 

 than the surface material, these consisting of white gravelly frag- 

 ments of calcareous rock and coarse sand resulting from the disinte- 

 gration of the underlying formation. The color gradually becomes 

 lighter with depth, and apparently the soil does not contain any 

 considerable quantity of organic matter below about 18 or 20 inches, 

 at which depth there is a rather abrupt change to the gray or white 

 color of the subsoil. 



The surface material apparently is only moderately calcareous. It 

 does not effervesce with acid until a depth of 12 to 15 inches is 

 reached. The subsoil characteristically is highly calcareous. The 

 loamy surface soil becomes slightly more compact at 10 to 12 inches, 

 without changing materially in texture, this condition apparently 

 being due to mineral cementation rather than to a concentration of 

 clay. The grayish subsoil, which is reached at depths of 18 to 24 

 inches, is more friable and pervious than the surface material. The 

 subsoil on the whole appears to be rather a product of disintegration 

 than of decomposition, and it gradually becomes coarser until it 

 grades into the hard or but little disintegrated, w^hite calcareous grit 

 of the Ogallala formation at a depth of 3 to 5 feet. The thickness of 

 soil material having a structure favorable for the retention of mois- 

 ture does not generally exceed 3 feet. 



The Sidney loam is widely distributed over the upland plain 

 throughout the county, occurring both in small and in extensive 

 areas. The topography is nearly level or gently undulating in the 

 larger areas. Some of the smaller areas occur as narrow strips of 

 gently sloping land at the base of steep slopes occupied by gravelly 

 types of the series and also in shallow, basinlike depressions at the 

 heads of draws. 



All the areas have good though not excessive surface drainage 

 and underdrainage. They are not subject to erosion. 



The Sidney loam is the most extensive soil type of the county. It 

 is arable and well suited to farming under semiarid conditions. At 

 present, however, probably not more than 3 per cent of it is under 

 cultivation. The remainder is utilized for grazing. 



Wheat is the principal crop, both winter and spring varieties being 

 grown. There is a smaller acreage of corn and oats, and several other 

 crops, including rye, barley, millet, amber cane, and alfalfa, are 

 grown in a small way. 



The yields of all crops show wide variations from year to year, 

 depending mainly upon the amount and distribution of rainfall. 

 Wheat yields in the last 10 years have ranged from less than 10 



