512 EXPERIMENT STATION EECOED. 



159 (1914), No. 18, pp. 617-622). — The author compares the modes of decompo- 

 sition of the aluminum silicate rocks of Madagascar and West Africa. 



In West Africa he distinguishes two zones of decomposition, namely, the so- 

 called zone of separation in which decomposition is governed bj- the nature of 

 the original rocks and above it the zone of concretion. In the first zone in the 

 ca.se of gabbros, diabases, and the nepheline syenites most of the silica, lime, 

 uuignesia, and alkalis are eliminated and crystalline aluminum hydrate pro- 

 duced. In the case of granites, gneisses, and mica-schists the decomposition is 

 progressive, first producing an aluminum silicate, sometimes crystalline but more 

 frequently colloidal, which is little by little transformed into the colloidal 

 hydrate. In the zone of concretion silica and other elements are eliminated and 

 in most cases the tendency is toward the formation of progressively pure alu- 

 minum hydrate in both crystalline and colloidal forms. The iron accomptinying 

 aluminum hydrate is usually in the hydrate form and moves by degi-ecs from the 

 lower to the upper zone where it accumulates, thus tending to form an iron crust 

 at the surface. 



The iron crust is usually absent from the Madagascar soils. The surface soils 

 are most frequently red soils and decomposition is not governed entirely by the 

 nature of the original rock. The laterization of diabases, basalts, and syenites 

 is similar to that in the zone of separation in African soils, and gneisses, mica- 

 schists, and granites are most frequently transformed into aluminum silicate 

 and colloidal aluminum hydrate, which is the most frequent cause of the red 

 soils. Granite and pegmatite are sometimes transformed into kaolin, free alu- 

 minum hydrate, and colloidal aluminum silicate. Another frequent mode of 

 decomposition not observed in Africa consists in the production from granite of 

 clear white laterite containing undecomposed quartz. The author concludes 

 that the red soils of Madagascar are not laterites but lateritic clays and 

 frequently only common clays. 



Soils of the Sassafras series, J. A. Bonsteel (f7, ;S. Dept. Agr. Bid. 159 

 {1915), pp. 52, pis. 9, fig. 1). — This bulletin deals with the distribution, charac- 

 teristics, crop adaptabilities, and fertility requirements of the soils of the Sassa- 

 fras sei-ies, which are confined in their distribution to the northern portion of the 

 Atlantic Coastal Plain, extending fi'om the southern end of the Chesapeake Bay 

 region through central and southern New Jersey to the western end of Long 

 Island, New York. 



The different soil tyi^es of the series range in texture from a gravelly loam 

 through sands and sandy loams to a heavy silt loam, and consist of water-laid 

 materials, chiefly formed as marine, estuarine, and fluvial terraces, but including 

 some areas formed by the deposition of glacial outwash materials. They 

 are distinguished by the yellow or brown color of the surface soils, by the yellow 

 or reddish-yellow color of the subsoils, and by the prevalence of an underlying 

 layer of gravel or gravelly sand at depths of from 2 to 6 ft. or more. 



" The drainage of the soils of the . • . series is generally good and only the 

 more level areas and those remote fi'om stream channels are decidedly in need 

 of artificial drainage. . . . The chief requirements for the improvement of crop 

 yields upon the different tyi^es . . . ai'e the more extended use of stable manure, 

 supplemented with the plowing under of green-manuring crops ; the use of lime 

 in some form, particularly in conjunction with the growing of the leguminous 

 forage and green-manuring crops ; the adoption in some sections of a crop rota- 

 tion which shall provide for the alternation of grass crops with the prevalent 

 system of grain growing; and local underdrainage on small areas of the heavier 

 textured types. [Thesel soils . . . are suited to intensive tillage for the growing 

 of market garden and truck crops upon the more sandy tyi^es, while the heavier 



