1916] SOILS FERTILIZERS. 721 



water-holding capacity (on account of the high percentage of organic matter) 

 and well supplied with all the elements of plant food. . , , Compared with 

 the American soils, the African soils (1) are much darker in color, (2) contain 

 much more organic matter (humus) and nitrogen, (3) contain more phosphoric 

 acid and potash, and (4) contain rather more of the finer grades of soil parti- 

 cles. It appears probable that these American and African samples differ essen- 

 tially in that In the one case the plant food (especially the nitrogen) must be 

 supplied in the form of readily available artificial manures while in the other 

 it can be obtained, in somewhat different form, from the natural reserves of 

 the soil. Therefore, even if the possible effect of differing climates and rainfall 

 is set aside, there are many points of difference between the two groups of soils, 

 any one of which may have an important influence on the quality of the crop." 

 Bed soil, P. V. De Regny (Internat. Inst. Agr. [Rome}, Mo. Bui. Agr. Intel, 

 and Plant Diseases, 6 (1915), No. 9, pp. 1133-11S8). — The author reviews work 

 by himself and others bearing on the subject and reports analyses of Karstian 

 red soils from various localities. 



It is concluded " that there are similar but not identical types of red soil and 

 that they may have various origins; in nature the same effect is not always 

 produced by the same cause. There are, therefore, red soils of different compo- 

 sitions, more or less ferruginous, or calcareous, or rich in alumina, produced 

 either by direct or by indirect weathering of the limestone or by aeolian action. 

 . . . Red soils, at least in their most typical manifestations, must be considered 

 as of a prevailingly colloidal type of formation." 



Analyses of soils of Stewart County, W. A. Worsham, Jb., L. M. Caeteb, 

 D. D. Long, and M. W. Lowey {Bui. Ga. State Col. Agr., No. 99 (1915), pp. 

 59, figs. 4). — This bulletin reports general soil survey data of the county, much 

 of which has been previously noted from another source (E. S. R., 34, p. 120), 

 and contains chemical analyses of each soil type mapped, together with a sum- 

 mary of the average of analyses for each type. " Taking the average of all the 

 soils of the county, the analyses show the plant food content to be as follows : 

 Nitrogen 0.02.5, phosphoric acid 0.045, and potash 0.508 per cent." These results 

 are taken to indicate that nitrogen is the limiting factor of crop production in 

 the county. 



Notes on some west country soils, C. T. Gimingham (Jour. Bath and West 

 and South. Counties Soc., 5. ser., 9 (1914-15), pp. 51-61). — The author discusses 

 the physical properties and fonnation of soils and describes the soils, especially 

 of Gloucestershire, Somerset, and Wiltshire, England, with reference to their 

 relationship to the geological strata underlying them. 



A new method for mechanical soil analysis, S. OofiN (Internat. Mitt. 

 Bodenk., 5 (1915), No. 4, pp. 251-311, figs. 15; abs. in Ztschr. Angew. Chem., 28 

 (1915), No. 77, Referatenteil, pp. 486, 487). — A method is described which is 

 based on the rate of sedimentation of the particles of a water suspension of 

 soil as measured by the rate of the increase in. weight of the settled matter. 

 Preliminary experiments with the method are also reported. It is thought that 

 this method may be useful in analysis of soils with slight variations in the 

 size of particles of different strata or for saving time in the ordinary analysis. 

 The apparatus used is also described and illustrated. 



Judg'ing soils on the basis of the hydrochloric acid extract and process of 

 exchange of bases, A. A. J. von Sigmond (Internat. Mitt. Bodenk., 5 (1925), No. 

 S, pp. 165-224, figs. 2; abs. in Chem. Abs., 10 (1916), No. 1, p. 80).— It was 

 found that detailed chemical analyses of hydrochloric acid extracts of soils gave 

 characteristic comparative values as to the soil-forming factors which could 

 not be obtained by lump analyses. 



