SOILS OF EASTERN VIKGINIA. 33 
100 barrels. The estimated mean production is about 60 barrels. 
It must be remembered that the spring crop is harvested to bring the 
largest cash return per acre and that this is accomplished by digging 
a part of the crop at an early date to obtain the higher prices, while 
the rest of the crop, harvested at a later date, produces a larger yield 
per acre, but is sold at a lower price. Thus, the 30-barrel yields 
represent chiefly the earliest digging, while the larger yields result 
from permitting the crop to come more nearly to maturity. Under 
the system practiced in the Norfolk district, it is evident that, within 
reasonable limits, yield per acre is affected chiefly by the date of 
harvest. 
The methods of management employed with the potato crop are 
evidently very uniform in the district. The early crop of potatoes 
is usually followed by a summer crop. In many cases volunteer 
grass, chiefly crab grass, is permitted to occupy the land and later 
harvested for forage. In other cases the land is occupied immediately 
after the harvesting of the potatoes by a crop of corn or by corn with 
cowpeas or soy beans sown in alternate rows. Following the harvest 
of the summer crop, either a winter truck crop is planted or, in some 
cases, rye and crimson clover are used as winter cover crops. The 
common practice, however, is to follow potatoes with a summer 
forage crop and then use the land for a winter truck crop. 
Fertilization for the potato crop is practically standardized in the 
Norfolk district. Under normal conditions a commercial fertilizer, 
analyzing 7 per cent of ammonia, 6 per cent of phosphoric acid, and 
5 per cent of potash, is used at the rate of 1,200 to 2,000 pounds per 
acre. During the shortage of potash salts caused by the war the 
practice was to increase the amount of phosphoric acid. A common 
formula being 7 per cent ammonia and 8 or 9 per cent phosphoric 
acid with no potash or, in a few instances where it could be obtained, 
1 to 3 per cent potash. 
Stable manure is used for the potato crop, so far as it is obtainable. 
It is chiefly purchased from local sources of rather limited supply. 
(See PL XI, figs. 1 and 2.) 
Careful cultivation of the potato crop is the rule in the Norfolk 
district. Poisons are applied to control the potato beetle and some 
of the more progressive farmers spray with Bordeaux mixture to 
counteract the blight. 
It should be noted that the Norfolk district produces the Irish 
Cobbler almost exclusively for the spring crop of potatoes, and grows 
a relatively small acreage of '^ Peach Blow" potatoes as a fall crop. 
Cahhage. — Replies were received from 19 growers, representing a 
total of 242 acres of cabbage. Five of the replies, or 26 per cent of 
those reporting, indicate a preference for a sandy loam soil for cabbage 
61681°— 22— Bull. 1005 3 
