SOIL SITRVEY OF LOUISA COUNTY, IOWA. 



29 



bushels; and ryo, 10 to 25 bushels, averaging 18 ])ushels. Alfalfa 

 does quite well, and yields about the same as on the Grundy silt loam. 



Land of this type sells at prices ranging from $75 to $175 an acre, 

 and averaging about $115 an acre. 



Barnyard manure and green-manure crops should be plowed under 

 whenever practicable in order that the humus supply may be built up. 

 Contour plowing on slopes will reduce soil washing and tend to pre- 

 vent the forming of gullies. The more general sowing of alfalfa, 

 which is grown more extensively on the same character of soil in other 

 localities, would doubtless prove profitable and beneficial to the soil. 



The following table gives the results of mechanical analyses of 

 samples of the soil and subsoil of the Clinton silt loam: 



Mechanical analyses of Clinton silt loam. 



TAMA SILT LOAM. 



The Tama silt loam is a dark-brown silt loam, with a depth of 14 

 inches, underlain by a dark-brown silt loam tinged with yellowish 

 brown, which gradually becomes more distinctly yellowish brown 

 and at 18 inches changes to a silty clay loam. Frequently dark- 

 brown to black concretions occur in the lower su})soil. In a few 

 locations, as about 1 mile east of Bethel Chm'ch, surface wash has 

 caused the surface soil to assume the texture of a loam or fine sandy 

 loam, but these areas of coarser texture are too small to map sepa- 

 rately. Along depressions within the areas of this type small patches 

 of Grundy sUt loam and silty clay loam frequently occur. 



This type generally occupies strips along the slopc^s of drainage 

 channels, intermediate between the Grundy or Muscatine and the 

 Clinton or Lindley. Where the Clinton and Lindley are absent it 

 separates the fiat upland soils from the first-bottom or terrace soils. 

 It occurs on slopes where the angle is such as to permit sufficient 

 aeration to oxidize the subsoil and give it a solid yellowish -brown 

 color without mottling, but where the encroachment of the timber has 

 not caused the surface soil to have a light color. Both as to position 

 and composition the type may be said to be intermediate between the 

 Grundy or Muscatine silt loam and the Clinton silt loam. The topog- 

 raphy is gently rolling to rolling, and drainage is well established. 



Although not as extensive as the Grundy, Muscatine, and Clinton 

 sUt loams, the Tama silt loam is of considerable importance agricul- 



