STUDY OF SMALL FARMS NEAR WASHINGTON. 13 
is probably greater than that of the fertilizer used. The supply of 
stable manure in the city is limited, however, and some farmers are 
unable to get the required amount. 
The importance of maintaining enough humus in the soil is ap- 
preciated by all the experienced farmers. Barnyard manure is their 
chief reliance for this purpose, though rye, crimson clover, or cow- 
peas are sown occasionally, to be plowed under as green manures. 
The growing of winter cover crops could be practiced to good advan- 
tage much more commonly. Most of the crops grown on these farms 
are cultivated throughout the summer, furnishing an excellent seed- 
bed in the fall for rye or some winter legume to be plowed under the 
following spring. Such crops furnish considerable humus to the soil, 
which the trucker finds it increasingly difficult to supply, and also 
tend to prevent serious washing of the soil in the spring. The winter 
cover crop should be plowed under while the stems are still succu- 
lent, and the land then very thoroughly worked before the truck 
crop is planted. 
INCREASING ACREAGE BY DOUBLE-CROPPING. 
Much of the crop land on these farms is double-cropped. The 
farmers with 20 acres and under of tillable area raise two crops dur- 
ing the year on about 30 per cent of their crop land, and those with 
over 20 acres of tillable area raise two crops on about 20 per cent of 
their crop land. This is a profitable method of increasing the crop 
acreage on small farms. The above-mentioned two groups of farms 
were subdivided into two groups each, those double-cropped on less 
than 25 per cent of their crop area, and those double-cropped 25 per 
cent and over of their crop area. The labor incomes of the farmers 
in the first group were $89 for those double-cropping less than 25 
per cent of their crop area and $295 for the rest, while in the second 
group the labor incomes were, respectively,- $658 and $1,162. 
The importance of having crops growing all the time can not be 
overemphasized. Many truck crops require only a portion of the 
season for reaching maturity. // it is not possible to follow or pre- 
cede the short- growing crop with another truck crop, a winter cover 
crop or summer legume should be sown, to be plowed under to im- 
prove the soil. 
The number of acres double-cropped also materially affects 
efficiency in the use of horses. The crops worked per horse for the 
above-mentioned groups as subdivided on double-cropping were 5.9 
acres for those in the first group who double-cropped less than 25 
per cent of their crop area, and 9.1 for the rest, and 10.7 and 12.7 
acres, respectively, for those in the second group. The efficient em- 
ployment of horses is very important on these small farms, where 
