26 



FIELD OPERATIONS OF THE BUREAU OF SOILS, 1918. 



The productiveness of the Grund\' silty clay loam can be in- 

 creased by the apphcation of lime, the incorporation of all the 

 vegetable matter possible through the plowing under of a green- 

 manure crop whenever feasible, and a greater depth of plowing to 

 be attained gradually. 



The following table gives the results of mechanical analyses of 

 samples of the soil and subsoil of the Grundy silty clay loam: 



Mechanical analyses of Grundy silty clay loam. 



MUSCATINE SILT LOAM. 



The surface soil of the Muscatine silt loam is a dark-brown to 

 black, friable silt loam, extending to a depth of 12 inches, underlain 

 by a dark-brown or medimn-brown, heavy silt loam, which soon ])asses 

 into a silty clay loam. At 22 to 24 inches the subsoil becomes mottled 

 light bluish gray and jrellowish brown with a lesser amount of rusty 

 brown, and contains some dark-brown to black iron concretions. 

 In the lower part of the 3 -foot section the texture frequently approxi- 

 mates silty clay, but the type never becomes as heavy and compact 

 as the Grundy silt loam. The type as it occurs in this county is 

 quite uniform. In some of the less well drained places the light 

 bluish gray color in the subsoil is displaced by dark bluish gray. 



The Muscatine silt loam is the predominant t}^)e of the eastern 

 upland. With the exception of a few included areas of Muscatine 

 silty clay loam, it occupies the greater part of the upland back from 

 the bluff and back from the better drained sections. The tyj)e 

 generally adjoins the Tama silt loam, but occasionally the Clinton 

 silt loam, and very rarely the Lindley silt loam. The topography 

 is level to gently rolling. Both surface run-off and underdrainage 

 are generally good, though there is a slight inclination to seepiness 

 in some places. 



As previously stated, this soil and the Grimdy silt loam differ 

 almost imperceptibly, the former being mapped in the eastern up- 

 land and the latter in the western, the Iowa River being taken as the 

 boundary. This somewhat arbitrary separation is necessitated by 

 the gradual lightening of the color and texture of the subsoil to the 

 north. 



The principal crops grown on the Muscatine silt loam are corn, 

 oats, hay, and, to a lesser extent, wheat. Winter wheat is grown on 

 the eastern upland almost to the exclusion of spring wheat. Yields 



