THE CARRINGTON CLAY LOAM. 5 



The type occurs under a fairly wide range of climatic conditions 

 and the more northern areas, which possess a cooler climate, are also 

 the more western ones, within which a smaller rainfall is experienced 

 than those to the south and east where the type is developed. These 

 differences in climatic environment, coupled with considerable dif- 

 ferences in the length of time which the soil has been agriculturally 

 occupied in the different areas give rise to variations in crop uses. 



In all of the more southern and eastern areas the growing season 

 is sufficiently long to produce the standard varieties of corn, while 

 in the extreme northern areas only the short-seasoned varieties can 

 be grown. Corn is therefore a standard and general crop for the 

 Carrington clay loam in Wisconsin, southern Minnesota, and Iowa, 

 while it is grown only to a limited extent in North Dakota. In Min- 

 nesota spring wheat is the great staple grain crop upon the Carring- 

 ton clay loam and associated types^ while oats are more generally 

 grown upon it in Iowa and Wisconsin. In all of the areas, except in 

 North Dakota, hay is recognized as especially fitted to this soil and 

 considerable areas of it are in mowing land or pasture. In the newer 

 communities wild grass may yet be cut upon the sloughs and marshes 

 and there is a corresponding limitation of the acreage seeded to the 

 tame grasses, although these are known to produce excellent yields. 



Local selections of crops adapted to production upon the type are 

 thus made to suit corresponding variations in climate or market 

 requirements. 



IMPROVEMENT IN SOIL EFFICIENCY. 



The Carrington clay loam is an unusually fertile and lasting type of 

 soil. It is well supplied with organic matter in its natural condition 

 and the natural drainage is good over the greater portion of the 

 type. Locally the laying of single lines of tile through sloughs or 

 to afford drainage outlets for small depressed areas would increase 

 the area of the type under tillage and would make the fields more 

 uniform in their cropping capacities. In all of the older communi- 

 ties this improvement has been quite generally effected. In areas of 

 cheaper lands many thousands of acres of this type should be so 

 improved as intensity of cultivation increases. 



In many of the newer communities pioneer crops are yet produced 

 and the endeavor is to seed as many acres of this soil as possible to 

 the small grains, especially spring wheat or durum wheat in the 

 region of less rainfall. This one-crop system does not tend to main- 

 tain the high crop-producing power of the soil and necessitates fal- 

 lowing with the alternative of decreased crop returns. The adop- 

 tion of a regular crop rotation is, therefore, desirable and a tilled 

 crop should be brought into the rotation to free the ground from 

 weeds. Grass, including a legume, should also be grown after the 



