646 EXPEEIMENT STATION RECORD. 



pj). 488-491). — The author discusses the principles of the genetic classitication of soils 

 and the complex nature of the processes of soil formation as dependent upon parent 

 rock, temperature, and moisture. The influence of the parent rock is of a passive 

 character, while that of heat and moisture is active, giving rise to a predominating soil 

 process for each climatic zone. Thus near the poles and in arid deserts the predomi- 

 nating process is one of physical weathering, while in other regions chemical and 

 biological actions assist ])hysical action. 



In the tropical zone, with a clearly defined sea climate, i. e., higli temperature and 

 liumidity throughout the year, the ])redominating processes are chemical and biolog- 

 ical, resulting in tlie formation of lateritic and allied soils. 



In subtropical regions, with lower temperature and humidity, the chemical and 

 biological processes are interrupted during the winter, and the predominating process 

 is the accumulation of neutral humus, resulting in the formation of chernozem or 

 alkali soils, according to the character of the parent rock. 



In temperate zones, in which the temiierature is still lower while tlie liumidity is 

 considerable, the predominating process is one of leaching, resulting in the formation 

 of soils of the podzol class. 



The forest soils the author does not consider as a genetic zone. Their origin dejiends 

 on the replacement of predominating process (accumulation of neutral humus) by 

 another (podzol formation), owing to the change of the balance of hunudity in the 

 soil. Marshy and inundated soils depend on the constant pr temporary predominance 

 of moisture. — p. fireman. 



Report of the geologist, E. H. Barbour {Nebraska Stale Bd. Ayr. Rpt. 1901, pp. 

 239-266, figs. 6). — Tliis contains an article on volcanic ash in Nebraska soils, a direc- 

 tory of the limestone quarries of Nebraska (by C. A. Fisher), and a bibUography of 

 the geology of Ne])raska. The origin, distribution, nature, and uses of the volcanic 

 ash found generally throughout not only Nebraska, ]jut western Iowa, South Dakota, 

 Oklahoma, Kansas, Colorado, Wyoming, and IMontana, and regions farther west are 

 discussed. At present the material "is used for polishing and scouring kitchen ware, 

 and as a base for scouring soap. . . . 



"Its chemical composition, according to analyses by Pi-of. H. H. Nicholson, of the 

 department of chemistry of the State university, is as follows: Organic matter, 8.75 

 percent; silica, 68.91 percent; lime, 3.44 per cent; sodium oxid, 3.09 per cent; potash, 

 0.36 per cent; sulphuric acid, 8.88 per cent; iron oxid and alumina, 6.12 per cent; 

 total, 99.55 per cent. Geologically this deposit seems to be confined to the more 

 recent deposits, and has not been found below the oligicene, but does occur in beds 

 of varying thickness and extent from that jioint up to the latest formations." 



The location and size or condition of the limestone quarries of the State are given. 

 "The limestone formations in Nebraska are the Niobrara, Benton, Permian, and 

 Carboniferous. The surface area of these formations comprises about a dozen coun- 

 ties in the southeast corner." 



The geological bibliography includes an alphabetical list (l^y authors) of 315 titles 

 of articles on geography, physiography, stratigraphy, resources, water supply, etc., 

 compiled from every available source. " Paleontological papers dealing mainly with 

 the descriptions have not been included in every case." 



Effects of difiFerent systems of manuring upon tlie amount and quality of 

 the humus in the soil, W. Frear and E. H. Hess {Pennsiflvania iSta. Ejd. 1901, 

 pp. 173-180). — As sui^plementary to a previous report (E. S. R., 13, p. 330) the 

 results are given of studies of the humus contents of the soil of a series of plats 

 which have for a long period "received applications of 6 tons per acre every alter- 

 nate year for the corn and wheat in an ordinary four-course rotation of corn, oats, 

 wheat, and grass." The results show that "nearly 20 years of fertilizing by biennial 

 applications of yard manure, in which about 534 lbs. of nitrogen were contained, 

 has resulted in an increase, relative to land cropped identically but receiving no 



