THE MARSHALL SILT LOAM. 13 



more attention is being paid to crop rotation in the more eastern 

 sections where the type occurs. In general the rotations have been 

 worked out by natural selection and by the elimination of unsuitable 

 crops from the farm practice. The first obstacle to the wider intro- 

 duction of rational crop rotations lies in the not unnatural desire to 

 produce as many crops of corn as possible and to devote the largest 

 possible acreage of this soil type to maize production. As a result 

 there has naturally been built up in the best farming sections, upon 

 the Marshall silt loam, a crop rotation which ordinarily consists of 

 the production of two or three crops of corn in succession, followed 

 by a crop of oats, sown upon the "stalk land" in the spring. With 

 the oats, either timothy and clover are seeded in or clover alone. 

 After the removal of the oat crop the grass is allowed to occupy the 

 land for two years or at the most for three, when the sod is plowed 

 and several corn crops are again planted in succession. In the major- 

 ity of instances in Indiana, Illinois, and the eastern portions of Iowa 

 and Missouri this rotation is adequate and well suited both to the 

 soil and to the agricultural necessities. 



This rotation is modified in southwestern Iowa and northwestern 

 Missouri by the production of larger areas of winter wheat and 

 smaller areas of oats. In this instance the winter wheat merely 

 takes the place of the oats in the rotation, although in some instances 

 the seeding to grass is also omitted, and the rotation becomes a mere 

 alternation of two or three crops of corn, succeeded by a crop of 

 wheat. Under this latter practice the yields of either grain are 

 maintained only with difficulty. 



West of the Missouri River the omission of crop rotation is fre- 

 quent, and corn is raised successively as long as an adequate crop 

 may be secured. Then wheat is sown for several years in succession 

 until yields are reduced, and a return is made to corn growing. This 

 practice is rapidly passing away and systematic crop rotation is taking 

 its place with marked benefit, as shown by increased yields. 



Very little commercial fertilizer is used in any locality for any pur- 

 pose upon the Marshall silt loam, and in some localities which it 

 dominates the use of fertilizers is decreasing rather than increasing. 

 In too many instances the application of stable manures is neglected 

 and the numerous streams which intersect the prairie section of 

 the more western States are used as the depositories for this mate- 

 rial. This is a serious waste and one which should not occur under 

 any well-regulated system of agriculture. In fact the application of 

 stable manures is usually marked by increased crop yields and by a 

 greater certainty of producing the crop, especially under conditions 

 of moderate drought. 



Fruit crops. Only in a few localities has the Marshall silt loam been 

 utilized as an orchard soil. The notable exceptions to this occur prin- 



