1917] SOILS — FERTILIZERS. 619 



soils during six years the value of the crops per acre has been increased $73.37 

 by nitrogen and only 22 cts. by phosphorus in addition." 



A list of 34 available publications relating to Illinois soil investigations is 

 appended. 



Tazewell County soils, C. G. Hopkins, J. G. Hosier, E. Van Axstine, and 

 F. W. Garrett {Illinois Sta. Soil Rpt. 14 {1916). pp. 68, pis. 2, figs, ii).— This is 

 the fourteenth of the Illinois county soil reports. 



Tazevs^ell County is located a little north of the central part of the State, 

 principally in the earlier Wisconsin glaciation. The general topography of the 

 county is gently rolling with the exceptions of the northwestern and eastern 

 parts, where small streams have broken the upland into a series of hills and 

 valleys. Natural underdrainage exists over a large part of the gravel terraca 

 An area in the southwestern part of the county needs artificial drainage. 



The soils of the county include (1) upland prairie soils rich in organic mat- 

 ter, (2) upland timber soils, (3) terrace soils, and (4) swamp and bottom lands, 

 covering, respectively, 37.62, 24.91, 22.01, and 14.36 per cent of the area. The 

 brown silt loam is the most extensive single type. " The most significant facts 

 revealed by the investigation of the Tazewell County soils are the lack of lime- 

 stone and the low phosphorus content of the common prairie soil and of the 

 most extensive timber types, which combined cover nearly 60 per cent of the 

 entire county." 



The principal soil areas of Iowa, W. H. Stevenson {Imca Yearbook Agr., 

 16 {1915), pp. 581-592, fig. i).— This report states that there are four distinct 

 classes of soils in Iowa, geest, alluvium, loess, and till. The two latter are 

 the most important, comprising about 93 per cent of the area of the State. 

 There are three distinct areas of loess soil, the Missouri loess in western 

 Iowa, the Mississippi loess in eastern Iowa, and the loess of southern Iowa. 

 There are three distinct areas of glacial till, the Wisconsin, the lowan, and the 

 Kansan. 



The principal soil problems of these different areas are as follows: (1) Drain- 

 age, which affects especially the Wisconsin drift area and the wide river bot- 

 toms, and in a lesser degree the Iowa drift area and the hilly Kansan drift 

 area in southern Iowa; (2) treatment of the so-called alkali spots of the newer 

 drift areas; (3) treatment to restore the fertility of the leachy areas of the 

 loess and the lowan drift area; (4) treatment of the gumbo, the geest, the 

 ferretto, and the clay hills of southern Iowa according to the special require- 

 ments of the different cases; (5) prevention of soil erosion, which is the source 

 of enormous loss to Iowa and a constant menace in the hilly regions; (6) treat- 

 ment to cause the loess soils to warm up more quickly in the spring; (7) ex- 

 periments to find the difference in productiveness shown by certain areas as 

 regards certain crops and to find how these differences may be equalized ; and 

 (8) experiments to determine the most practicable system of crop rotation for 

 each principal area. 



Soil survey of Grenada County, Mississippi, W. E. Tharp and J. B. Hogan 

 {U. S. Dept. Agr., Advance Sheets Field Operations Bur. Soils, 1915, pp. 32, 

 fig. 1, map 1). — This survey, made in cooperation with the State of Mississippi, 

 and issued January 27, 1917, deals with the soils of an area of 284,160 acres 

 in north-central Mississippi, the greater part of which consists of rolling to 

 hilly uplands, in places very rough. The western end of the county lies in the 

 Mississippi flood plain. 



" The upland soils of the western and central parts of the county are of 

 loessial origin. In the eastern half of the county the loess is seldom more than 

 a few feet deep, and the underlying coastal plain material, consisting mostly 

 of sand and clay, enters largely into the composition of the soils." 



