VERTICAL FARMING 15 



that will permit the giving up of its mineral plant foods to the 

 roots of plants. These changes have gone on more slowly in 

 the stiffer subsoils, and much of the mineral substances have 

 not been acted upon sufficiently by the air and by bacteria to 

 give up the needed foods. Deep cultivation and the use of 

 explosives open up these soils to the action of the air and other 

 agencies so that these foods may be prepared for the roots, arid 

 increased fertility and greater returns in crops are the result. 



Soil Areas, Series, and Names. The soils of the United 

 States are classified into thirteen subdivisions called " Soil 

 Provinces," or regions, according to the essential geographic 

 features, such as the Atlantic and Gulf Coastal Plains Province, 

 the Appalachian Mountain and Plateau Province, the Great 

 Plains Region, the Arid Southwest Region, and the Pacific 

 Coast Region. The soils of a province are classified in soil 

 series. The soils in a series have the same range of color, same 

 general character of subsoil, a common or similar origin, about 

 the same structure, and broadly, the same type of relief and 

 drainage. The soil series are divided into individual soils, which 

 generally receive local names, as: Portsmouth Sandy Loam, 

 which is found in several states from Delaware to Mississippi ; 

 Vermont Silt Loam, of Kansas and Texas ; and the San Joaquin 

 Fine Sandy Loam, of the Pacific Region. A soil class includes 

 all the soils having the same texture, and are called: sands, 

 loams, clays, fine sandy loams, clay loams, clay loam adobe, or 

 such other combination of descriptive words as best fits the 

 peculiarity of the soil. 



Maps of the soil surveys of the various provinces, and 

 descriptions of the series and individual soils of the surveyed 

 areas will be found in the annual reports of the U. S. Bureau 

 of Soils, and may be consulted at the larger public libraries ; or 

 if a particular county has been mapped, the report on it can be 

 gotten from the U. S. Department of Agriculture. 



Chemistry of the Soil. While it is true that the productive- 

 ness of a soil depends more on its physical character and con- 

 dition than upon its chemical composition, yet the chemical ele- 



