Kellogg and Orvedal 9 



Gray-Brown Podzolic soils 



The Gray-Brown Podzolic soils are dominant in the agriculture of 

 the United States from Minnesota east and Tennessee north, and in 

 the northwestern part of Europe. Like other podzolic soils, these are 

 leached, acid, and relatively low in most plant nutrients in available 

 form. They are also rather low in organic matter. Despite these fertility 

 deficiencies, they are highly responsive to management. With lime and 

 fertilizers, they support a very wide range of crops. We have learned 

 to make from them fertile, arable soils that give high yields. 



Phosphatic fertilizers and lime are needed on nearly all of these soils. 

 The amounts of potassium and nitrogen required depend upon the 

 legumes grown and the animal manures available; but, usually, at 

 least some chemical fertilizers containing these nutrients are required 

 for optimum efficiency. In many places magnesium and boron are 

 needed for some crops. Responses have been reported for most of the 

 nutrients, but, generally speaking, deficiencies of the minor elements 

 are less common than on the soils of warmer regions. 



Western civilization grew up on the Gray-Brown Podzolic soils and 

 expanded from them onto others. Most of the research on soils and soil- 

 plant relationships, especially during the nineteenth century, was con- 

 ducted on these soils and their close relatives. The results have been 

 dramatic. From the fall of Rome nearly to the French Revolution, 

 grain yields in Europe were around six to ten bushels to the acre. With 

 the adoption of crop rotations, they nearly doubled. Not only that, the 

 elimination of the fallow year gave more acres for harvest. The appli- 

 cation of chalk and farm manures became general. In Germany, wheat 

 yields went to about 16 bushels to the acre by 1850. At the same time, 

 they were 14 bushels to the acre in France and somewhat over 20 

 bushels in Britain. By 1906, they had gone to 30 bushels in Germany 

 and to over 30 in Britain, while they were about 20 in France. Now 

 they stand at about 35 in Britain (4). Something more than one-half 

 of the increases in Britain and Germany came before the common use 

 of chemical fertilizers after 1850. 



This remarkable increase in production has been attained through 

 the use of improved techniques, most of which have grown out of 



