416 EXPEEIMENT STATION RECORD. 



physiography, topography, and formation of the soils and more fully with soil 

 material and soil types, chemical composition of the soil, and field tests of the 

 fertilizer requirements of some of the prevailing types. 



Lake County lies in northeast Illinois in the late Wisconsin glaciation. The 

 soils of the county are divided into four classes, as follows : (1) Upland prairie 

 soils, usually rich in organic matter, (2) upland timber soils, including nearly 

 all upland areas that were formerly covered with forests, (3) terrace soils, 

 which include bench lands or second bottom lands that were formed at the time 

 of the melting of the glacier, and (4) swamp and bottom land soils, which 

 include the overflow lands or flood plains along the streams, the swamps around 

 some of the lakes, the poorly-drained lowlands, and the area of sand beaches 

 deposited by Lake Chicago. 



The yellow-gray silt loam of the upland timber soils covers about 40 per 

 cent of the county, the brown silt loam of the upland prairie soils about 28 

 per cent, and the swamp and bottom land soils about 15 per cent. It is empha- 

 sized that the supplies of some of the necessai-y elements of fertility in the 

 plowed soil of the most prevalent types in the county are extremely limited 

 when measured by the needs of large crop yields. The variation among the 

 different types of soils in the county with reference to their plant food content 

 is also very marked. " Thus, the yellow silt loam contains in 2,000,000 lbs. of 

 surface soil sufiicient total nitrogen for 12 ' maximum ' crops of corn, suflScient 

 phosphorus for 31 crops, and potassium for 800 such crops; while the deep 

 l^eat contains in 1,000.000 lbs. of surface soil, nitrogen for 217, phosphorus for 

 67, and potassium for only 53 com crops of 100 bu. each." It is stated that 

 more than 90 per cent of the soils of the county contain no limestone in the 

 surface or subsurface to a depth of 20 in. 



Improving Iowa's peat and alkali soils, W. H. Stevenson and P. E. Brown 

 (Iowa Sta. Bui. 151 (1915), pp. Jf3-79, figs. i5).— This bulletin describes the 

 peat and alkali soils of Iowa and reports fleld and laboratory studies to deter- 

 mine methods of reclamation and cropping which will render them profltably 

 productive. 



There are two classes of peat deposits in Iowa, namely, the shallow peat, 

 varying from a few inches to 3 or 4 ft. in depth, and underlain with a clayey or 

 muck subsoil ; and the deep peat, ranging from 5 to 15 ft. in depth. The shallow 

 peats tested contained an abundance of lime, nitrogen, and organic matter, but 

 the potassium and phosphorus contents were low. "The muck or clay tmder- 

 iying the shallow peats are, however, rich in potassium and contain some phos- 

 phorus, so that the lack of these two elements in the peat does not restrict crop 

 production to any large extent." 



Field tests of the shallow peats showed that limestone, gypsum, phosphorus, 

 and potassium applied alone or in combination in amounts in which such mate- 

 rials are usually applied to soils produced no profitable increase in crops. 

 These results are taken to indicate that the shallow Iowa peats do not need the 

 addition of commercial fertilizing materials to make them productive. Methods 

 of treatment recommended are (1) adequate drainage, (2) proper plowing and 

 cultivation, and (3) the choice of crops best suited to such soils. Fall plowing 

 and deep plowing are considered to be advisable for peat soils and timothy and 

 alsike clover are thought to be the best crops to grow on reclaimed peat soil. 



The salt depo.sits on the surface of the alkali soils of Iowa consist mainly of 

 calcium carbonate and sodium in the form of sulphate and bicai-bonate and 

 occasionally nitrate. Tile drainage is considered to be the quickest method of 

 preventing the ai)pearance of alkali in these soils and a liberal application of 

 manure is the most effective means of removing the salts causing the alkali 



