SOILS — rERTILlZERS. 7l5 



the rich limestone area of the central basin is entered. On every hand are in- 

 dications of {jreatly increased soil fertility. ... In west Tennessee . . . the 

 soils are by natnre fairly fertile and dnrable, and are remarkable for the great 

 variety of croi)s whicU they prodnce to advantage, bnt have snffered nuicli from 

 one-sided cropping and from erosion. On the western bonndary, along the 

 Mississippi Kiver, are alluvial soils of almost unsurpassed fertility. 



" It is especially noteworthy that throughout the State each change in soil 

 type coincides to a marked extent with a change in the rock or other geological 

 formation from which the soil originated." 



It is stated that "practically all of the upland soils of this State are of 

 residual origin — formed where they lie, as the result of the decomposition of 

 the rock or other material similar to that which underlies them." Each 

 formation has given rise to soils of fairly well-defined physical characteristics, 

 such as color and texture and similarity of mineral constituents. Investigation 

 of the fertile and durable soils of the State appai-ently shows " little uniformity 

 in physical composition, that is, there are both rich and poor loams, silt loams, 

 clay loams, etc. In fact, there is only one apparent feature in which the soils 

 of similar productiveness under continued cropping closely resemble each other, 

 and that is their ct»ntents of the mineral elements of plant food, phosphoric 

 acid in particular." In other words, Tennessee soils have " originated from dif- 

 ferent formations, which were very unequally supplied with the mineral plant- 

 food elements, and the resulting soils have the same characteristics." 



The principal soil formations dealt with in the case of the east Tennessee 

 soils are Knox dolomite, shale, Chickamauga limestone, miscellaneous marbles 

 and limestones, Tellico sandstone, and alluvial. The soils of west Tennessee 

 are mainly " derived from geological deposits which were not r-onsolidated into 

 rock." 



Complete analyses of the "insoluble" residues from ordinary analyses of 12 

 soils " sho^v that the hydrochloric acid digestion removed in each ca.se most of 

 the phosphoric acid, lime, and magnesia, but that large amounts of pota.sh 

 were unacted upon." Examinations of a number of samples indicate that soil 

 acidity is general throughout the State. 



General recommendations regarding the best methods of cropping and fertiliz- 

 ing to increase and maintain the fertility of the soils are given with fertilizer 

 formulas for special crops and a discussion of the advantages of utilizing the 

 geological origin as a basis of classification of Tennessee soils. In the author's 

 opinion geological origin affords " decidedly the l)est means of grouping these 

 soils with regard l)oth to physical and to chemical composition. . .^. To base 

 the classification on texture and structure alone would be to ignoi'e the ex- 

 ceedingly important factor of plant-food supply, on whieh would depend not 

 only the use of fertilizers, but also to a great extent adaittability to kind of 

 farming." 



More light on the origin of the Missouri River loess, ,1. E. Todd {Proc. 

 loica Acad. Sci., IS iJ!)06), pi), 187-19.'f). — As a result of recent investigations 

 of a loess-like deposit of Lake Dakota the author concludes that while the mass 

 of the Missouri River loess will continue to be credited to aqueous forces a very 

 considerable portion will be found to be the work of wind. "The pinnacles 

 along the eastern verge of the trough of the Missouri in Iowa, including possi- 

 bly Council Bluffs in part, and the higher ridges south of the Missouri in 

 northern Nebraska, also in less degree south of the Platte, the extensive blanket 

 covering the broad divides, especially those between larger streams, may be 

 placed under this head." 



Agricultural geology, E. H. L. Schwarz (yatal Affr. Jour, and }Jin. Rcc, 

 10 {1907), \o. H, 1)1). 933-9.'f5). — This is an argument in favor of a ivvival of 



