MARYLAND GEOLOGICAL SURVEY 183 



commercial products, though lately cowpeas have been employed in 

 conjunction with the manufactured fertilizers. It is a fundamental 

 principle with the tobacco growers that the application of lime on 

 fields where the crop is to be raised injures the buniing quality for 

 which the tobacco is esteemed. In consequence, where tobacco is to 

 form part of the crop rotation the other crops of the rotation suffer 

 for lack of lime for the sake of the one year's growth of tobacco. 

 The soils of this region all require lime for the production of grain 

 and grass, and the present rotation, based on tobacco, does not permit 

 the Norfolk loam to produce other crops to its best ability. 



The CoUington sandy loam is a peculiar soil derived from the 

 decomposition in place of a greensand stratum. The resulting soil 

 is a medium sandy loam underlain by a sticky, heavy sandy loam. 

 The physical texture of this soil gives a warm seed bed, producing 

 quick germination, and a good subsoil reservoir to maintain a water 

 supply during the period of growth, while its chemical composition 

 insures a good supply of potash salts, one of the most expensive plant 

 foods when purchased as a fertilizer. The complete commercial 

 fertilizer is not required on this soil so much as an application of 

 phosphate rock, coupled with the production of cowpeas to supply 

 nitrogen. These should be plowed under, in order to furnish addi- 

 tional organic matter. This soil type produces good crops of wheat, 

 corn, tobacco, and grass, and is also adapted to Irish potatoes and 

 fruit. In its sandier portions it raises good truck crops. 



The Susquehanna clay constitutes one of the most intractable soils 

 of the region. It is a sticky, plastic mass, difficult to cultivate, liable 

 to excessive baking in dry times, and comparatively unproductive 

 over a greater part of its area. Little has so far been accomplished 

 toward the solution of the agricultural problem it presents. The 

 extensive use of lime corrects its textural faults to some extent, and 

 good crops of wheat and clover have been produced under this treat- 

 ment. 



The Susquehanna clay loam possesses a loose sandy or loamy soil 

 capable of cultivation and of forming a natural mulch over the dense 

 clay of the subsoil. As a consequence it forms a fair seed bed and 

 yields medium crops of grain and grass. 



