242 AGRICULTURAL INDICATORS. 



The loess and glacial soils of the prairies are so completely cultivated that 

 they hardly need consideration as to their indicators. The luxuriance of the 

 three prairie associations and the large number of societies, especially of 

 l^umes, denote an agricultural region of the first importance. To the west- 

 ward, the most extensive and important soils are gumbo or "hard land," 

 saline soils, and sandy soils, usually of the sandhill or dune type. Where it 

 is derived from the weathering of shales, as is frequently the case, the soil is 

 usually both gumbo and saline. As Shantz (1911) has shown, "hard land" 

 is primarily agricultural in the Great Plains, though its high echard is a serious 

 disadvantage during drought periods. Soils recently derived from shales, such 

 as the Pierre and the Graneros, however, bear a vegetation which suggests 

 that their greatest value is for grazing. The work of Hilgard (1906) and of 

 Kearney and his associates (1914) has shown that, in the Great Basin and 

 similar saline regions, sagebrush is the one reliable indicator of agricultural 

 land. While crops may be produced on land covered with Atriplex conferti- 

 folia or Kochia, it is only during years of exceptionally favorable rainfall, 

 which are too rare for successful farming. Hence, practically all saline 

 communities are indicators of grazing land, though such land may be con- 

 verted to agricultural use when the removal of alkali is economically feasible. 



The numerous sandhill and dune areas of the West bear distinctive indi- 

 cators which denote the varying degrees of fixation of the sand. Typically, 

 they are grazing areas, though they are usually interrupted or surrounded by 

 more stable areas, such as the wet valleys of the sandhills of central Nebraska 

 or the wire-grass lands of eastern Colorado, in which farming is possible. 

 Even for grazing, their value is much less than it should be, and in addition 

 there is a rapid deterioration of the cover where overgrazing is practiced. 

 There is no question that the carrying capacity could be greatly increased and 

 the tendency to "blow" correspondingly decreased by protection and seeding 

 or planting. The Bad Lands, which occur throughout the West, but especially 

 in the Rocky Mountain regions, likewise ofifer attractive regions for reclam- 

 ation. Although the soil is a hard clay instead of blow-sand and the erosion 

 is due to water in place of wind, sandhills and bad lands have much in common. 

 The destruction due to erosion is often rapid and complete, as well as recur- 

 rent. They occur almost wholly in grazing communities, and the study of 

 succession in both has reached a point where it is possible to make use of it as 

 the chief method of reclamation, as is shown in Chapter VI. The extremely 

 dissected topography of bad lands practically excludes agriculture, and in 

 general the communities of rugged and rocky areas indicate their classification 

 as grazing lands, even when climatic conditions might permit agriculture. In 

 the case of swamp and bog conununities, the direct indication is for grazing, 

 but since they need drainage in order to be put into adequate commission, 

 their classification should take this into account. When they are not too 

 high or too far north, the drained areas will permit farming, but when they 

 occur in the montane zone, or above, their chief value is for grazing (plat 60) . 



Shantz's results. Shantz's studies of indicators in eastern Colorado are 

 still the most complete and detailed account of the correlation of indicator 

 communities and soil. His conclusions apply with slight modification to the 

 entire short-grass association, and they also have much value for mixed 

 prairies: 



