18 



AGRICULTURE IN THE SEMIARID GREAT PLAINS. 



be remembered that this includes not only the storm water but the 

 seepage water also, the only considerable loss not included being the 

 evaporation from the surface of the stream itself. 



The North Platte River and its tributaries gather most of their 

 water from mountain areas where the precipitation is generally 

 greater than on the prairies, and in all of which the evaporation is 

 much less and the run-off much greater; yet the amount of water in 

 these streams is sufhcient to cover the area from which it has been 

 collected to the depth of only 1.5 inches in a year.^ 



SOILS. 



The soils are, in a measure at least, characteristic of the climate. 

 They are strictly dry-climate soils. Little difference in texture 

 between soil and subsoil is found. There is nearly everywhere a 

 high percentage of soluble salts, and in many of the valleys an excess 

 of alkali. This is due to the fact that there is not sufficient rain to 

 leach out the salts. The soil is not often wet to any great depth, 

 and over much of the region there is no seepage whatever, all the 

 water which gets into the soil returning to the air. There is then no 

 means by which these soluble mineral compounds can get away. In 

 nearly all the region a slightly whitish zone is observed at from 1 to 

 3 feet below the surface. This is due to the accumulation of salts 

 which have been carried down by the rain water and left behind when 

 the water was evaporated to the air. This zone marks the limit 

 below which the soil is not often wet.^ 



The soils are mostly fine sandy loams or silt loams, containing little 

 clay. These soils are locally called ''hard land." There are lim- 

 ited areas of dark-colored tillable sands, which, under ordinary till- 

 age withstand drought better than any other soils of the region. 

 Such soils are found north of Haxtum, Colo., north of Oshkosh, 

 Nebr., and in other places. There are large areas of sand hills on 

 which agriculture is out of the question, but within these areas are 

 numerous small valleys where the soil contains some humus and is 

 quite productive. In many of the valleys water is within, reach of 

 the plant roots, and here large ci:ops of native hay and some culti- 

 vated crops are produced. In many places on the Plains there is 

 more or less gravel, and considerable areas of adobe are found. The 

 adobe is heavy and hard to work, but most of the soils are porous 

 and easy to till when sufficiently moist. 



On account of the dryness of the climate there is usually a large 

 store of mineral plant food in the soil, but for the same reason it has 



1 See Bulletin 205, OlTice of Experiment Stations, U. S. Dept. of Agriculture, entitled "Irrigation in Wyo- 

 ming," by C. T. Johnson, State Engineer. 



2 This does not refer to the deposits of soft, impure lime rock locally called "magnesia and native lime." 



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