166 THE SOILS OF PRINCE GEOEGe's COUNTY 



are lacking in lime, phosphoric acid, and humus, and efforts to 

 improve them in these respects are desirable. 



In the field the results of the chemical processes of weathering are 

 shown by nearly every soil boring taken within the area of the Col- 

 lington sandy loam. The surface soil, which has a depth varying 

 from 9 to 20 inches under different conditions of cultivation, con- 

 sists of a loose, loamy, brown sand, usually containing considerable 

 coarse sand and small amounts of intermediate grades of soil par- 

 ticles down to silt and clay. The loamy nature differs from that of 

 ordinary soils in the fact that the rather coarse materials are bound 

 together by much finer materials, which are sticky rather than 

 plastic. Even this fine material when dry crumbles easily to the 

 touch into a powdery brown mass. The immediate subsoil differs 

 from the soil in texture and composition. The glauconite is passing 

 through intermediate stages of weathering, and has been sufficiently 

 transformed to constitute a sticky, claylike mass, in which dark- 

 green specks of glauconite can still be distinguished. The partly 

 weathered glauconite includes a considerable percentage of quartz 

 sand within its mass. The hydration of the iron salts produces a 

 yellowish ot greenish-yellow color in the subsoil. Usually at a depth 

 of 30 to 40 inches the greensand can be found in almost its original 

 state of purity. It has been much less attacked by the processes of 

 weathering than either the soil or the immediate subsoil. It still 

 maintains a considerable supply of potash, phosphoric acid and 

 lime — three plant foods commonly purchased at considerable expense 

 in the form of commercial fertilizers. The presence of this plant 

 food underneath the soil is manifested by the general productivity 

 of the entire area of the Collington sandy loam. 



In the Prince George's area this greensand marl, which occurs 

 along the numerous stream cuttings and natural cliffs, has only been 

 used to a slight extent as a source of fertilizer. In one case, it is 

 said, its copious application over an already sandy soil produced a 

 crop of wheat averaging 25 bushels per acre, and its effect was noticed 

 in several succeeding crops. In other areas, both in the United States 

 and foreign countries, the greensand marl has long been utilized as 

 an inexpensive though effective medium for restoring impoverished 



