282 FLORIDA GEOLOGICAL SURVEY-SEVENTH ANNUAL REPORT. 
is used to break up the hardpan layer and improve its condition 
for plant growth. 
The supply of organic matter which gives to the Portsmouth fine 
sand its characteristic dark color and loamy texture is rapidly de¬ 
pleted by cultivation unless frequent additions are made, the soil 
becoming ashy gray in color. Plowing under crops of cowpeas, 
velvet beans, or beggarweed is the best means of maintaining the 
organic-matter content where stable manure is not available. 
The strawberry industry has attained its highest development on 
the Portsmouth fine sand around Starke and Lawtey. The berries 
grown upon this type usually reach the market a little earlier than 
those grown on the heavier soils. 
Although the type is better adapted to early«truck crops, small 
areas in more remote sections of the county are devoted to staple 
crops. Corn yields average about 15 bushels per acre, seed cotton 
produces one-fifth to one-third bale per acre, and oats about 10 
bushels. Cabbage and tomatoes do well on the type. Sweet pota¬ 
toes average about 250 bushels. 
The price for which the Portsmouth fine sand is sold varies 
greatly with its proximity to market. In more remote sections it 
can be bought for $5 an acre, while that near market or shipping 
points, and suitable for strawberry culture, but unimproved, is 
valued at about $10. The most desirable areas, cleared, improved, 
and close to market, are held at about $80 an acre. 
PORTSMOUTH FINE SANDY LOAM. 
The soil of the Portsmouth fine sandy loam consists of a black 
or very dark gray fine sand having a high organic-matter content. 
At an average depth of 8 to 10 inches this material is underlain by 
a gray to nearly white fine sand, which continues to a depth gener¬ 
ally varying from 18 to 34 inches, where it passes abruptly into a 
drab, mottled drab and yellow, or mottled gray and yellow fine 
sandy loam to slightly plastic fine sandy clay. A hardpan layer, 
similar to that encountered in the Portsmouth fine sand, is some¬ 
times encountered in the sandy layer lying between the surface soil 
and the heavier subsoil, but the occurrence of hardpan in this type 
is rather exceptional, and where it does occur it is seldom as thick 
or dense as that found in the fine sand type. Wherever the fine 
sandy loam or mottled clay is encountered within the 3-foot soil 
section, areas otherwise resembling the Portsmouth fine sand were 
mapped as the fine sandy loam. 
