EFFECT OF DRYING SOILS ON WATER-SOLUBLE CONSTITUENTS 



195 



1. Drab,' or (Sharkey,*) clay. This is a drab colored clay soil, not well supplied with organic 

 matter, stifiF and more or less impervious to water, very diflkult to work as it is exceedingly 

 tenacious when wet and cloddy when dr>'. It occurs in large areas in the poorly drained 

 portions of the Mississippi bottom lands, especially south of St. Louis. It is more fully 

 described by Hopkins, Mosier and associates (34), Marbut and associates (65), and as Yazoo 

 clay by Coffey and others (11). 



2. Black clay loatn^ (Marshall black clay loam). This is a black clay loam soil, well sup- 

 plied with organic matter. It occurs in flat, depressed areas, former ponds or lakes, and is 

 very productive when thoroughly drained. It is described more fully by Hopkins, Mosier, 

 et al. {2)3), Marbut (65) and as Miami black clay loam by Coffey, Mosier et al. (12). 



3. Brown silt loam (Marshall silt loam). This is a brown silt loam soil of good open texture, 

 well supplied with organic matter, and very productive, occupying the rolling prairies of 

 Illinois, Indiana and Iowa. Described by Hopkins, Mosier et al. (35), Marbut (65) and 

 Coffey et al. (13). 



TABLE 5 



Organic matter* contained in these soils 



1. Drab clay 



2. Black clay loam 



3. Brown silt loam 



4. YeUow-gray silt loam 



5. White silt loam 



6. Dunkirk fine sandy loam 



ORGANIC 

 CARBON 



per cent 



2.07 

 3.19 



2.78 

 1.67 



0.435 

 1.856t 



TOTAL 

 ORGANIC 

 MATTER 



per cent 



3.57 

 5.5 



4.8 

 2.9 



0.75 

 3.20 



MOISTURE 

 EQUrVALENT 



per cent 

 41.6 

 32.4 



28.0 

 20.7 



* Figures on soils 1 to 4 furnished by Professor J. G. Mosier. 

 t This determination was kindly made by Dr. F. A. Carlson. 



4. Yellow-gray silt loam (Knox silt loam). This is a light colored, rolling timber soil, not 

 well supplied with organic matter. More fully described by Hopkins, Mosier et al. (33), 

 Marbut (65) and as Miami silt loam by Coffey, Mosier and others (13). 



5. White silt loam. This soil was not recognized as a separate type by the Bureau of Soils, 

 as its work in Illinois was done during the beginning of American soil surveying. It is a 

 very light gray silt loam, underlaid by a decidedly impervious stratum, known as "tight 

 clay." It is an unproductive virgin timber soil, very low in organic matter, in fact ahnost 

 nitrogen free, having but 0.7 per cent of organic matter. This soil is more fully described 

 by Hopkins, Mosier et al. (32). 



6. Sandy loam. This is the same soil that was used in e.xperiments 1 and 2. 



Soils 1 to 5, inclusive, are surface soils, 7 to 8 inches deep. Soils 1 to 4 have 

 been stored in the air-dry state for two or more years in an attic where the 

 humidity is very low and the temperature at times in summer, rather high. 



Table 5 gives the content of organic matter in these soils. 



» Name used by Illinois Agricultural Experiment Station. 

 * Name used by United States Bureau of Soils, in Bui. 96, p. 738. 



5 Soils 1 to 5, inclusive, were collected by the writer while a member of the staff of the 

 Agronomy Department, College of Agriculture, University of Illinois. 



