356 0. D. von Engeln — Factors influencing Percentages of 



present in tliem. Hubbard* sbows this very strikingly by con- 

 trasting the agricultural conditions in the north-aud-south- 

 adjacent Coles and Cumberland counties of Illinois; the former 

 of which lies almost wholly in the Early Wisconsin glaciation, 

 while the latter has a Lower Illinoian glaciation soil-cover over 

 the greater part of its area. In Coles County tile drainage is 

 practised, rich swamp lands are thus reclaimed, — in Cumber- 

 land such drainage is useless; primarily because tributaries to 

 main natural drainage streams are developed in so much greater 

 numbers as to ' make the map of Cumberland County appear 

 darker.' Land values in Coles County at the time the article was 

 written ranged between $75 and $125 per acre, with the aver- 

 age above $75 ; while in Cumberland County the prices were 

 from $15 to $40, with the average near $30. The value of 

 crops per acre of improved land was from $10 to $15 for Coles 

 County, and from $6 to $10 for Cumberland County. It has 

 been stated by Chamberlinf and others that soil particles are 

 at once wasted and mixed by wind and wash, and that the 

 mixing is so complete, even in humid regions, that nearly all 

 soils acquire the essential plant food constituents. If such 

 processes were effectively operative to insure the presence of 

 sufficient amounts of these elements for the largest crop pro- 

 duction, then the adjacent soils of the early and late glaciations 

 in Illinois should show greater similarities in crop productivity 

 and chemical composition. According to the data here pre- 

 sented, one may as reasonably conclude that different positions 

 in an erosion cycle make for differences in the percentages of 

 soluble salts present in a soil, and for differences in fertility, as 

 applied to farm crops. 



It was originally planned to base such comparisons and cor- 

 relations as are cited above from bulk analyses, on the far 

 gi eater number of published "acid digestion" analyses of soils. 

 Especially in mind was a comparison of the averaged HC1 sol- 

 uble analyses of alluvial soils, i. e., bottom lands subject to 

 overflow, from the residual regions ; with averaged analyses 

 of similar soils from the glacial regions of the humid, eastern 

 portion of the United States. By choosing alluvial soils the 

 assumption could be made that these are naturally greatly 

 commingled samples, representative of the contributive geolog- 

 ical formations of the various drainage basins ; and also that 

 the average of even a small number of' such analyses would be 

 typical of wide areas. Unfortunately analyses are not available 

 for such a comparison. The references given by Whitney:}: in 



* Hubbard, Geo. D., A Case of Geographic Influence Upon Human Affairs, 

 Bull. Am. Geog. Soc, vol. xxxvi, pp. 145-157. 1904. 



t Chamberlin, T. C, Soil Productivity, Science, Feb. 10, 1911. 



\ Whitney, Milton, A Study of Crop Yields and Soil Composition in Rela- 

 tion to Soil Productivity, Bull. 57, 1909 ; Bureau of Soils, U. S. Dept. of 

 Agri., pp. 65-90. 



