8 BULLETIN 713, U. S. DEPARTMENT OF AGRICULTURE. 
Farms of average size—about 300 acres—showed the most profit- 
able diversity when receipts were distributed about equally between 
wheat, tobacco, and live stock, with a few minor sources of income, 
such as clover seed, poultry, hay, and corn. 
ROTATION OF CROPS. 
Probably no other term has been repeated so often in discussing 
agricultural problems as the term “rotation of crops.” On most 
diversified farms everywhere some kind of crop rotation is practiced. 
Experience will teach farmers that, except under special conditions, 
one crop can not profitably be grown continuously. on the same plot 
of ground. When, for various reasons, complete rotation systems 
can not be carried out and when a sufficient amount of manure is 
not available to supply the needed humus and plant food, some land 
usually les idle a year or more at a time to recuperate. Such a prac- — 
tice is a source of great waste on farms, as already has been pointed 
out. 
When all the land on the farm is about equally adapted to such 
crops as can be grown in a locality, a quite regular crop rotation 
develops. Where such crop rotations prevail the farmer can predict 
with practical certainty the crop which will be grown on a certain 
field one or two years hence. In the locality where this survey was 
made, however, though the land is generally level to rolling in 
topography, there is considerable diversity of soil on different parts 
of any individual farm. This condition, together with the fact that — 
grass and: clover often miss a stand, makes it difficult to follow a 
definite system of rotation. Thirty-two farmers out of 342 stated 
that they followed no-system. The great majority, however, have 
some system which they aim to follow. In the majority of cases 
this was given as corn or tobacco, wheat, and grass and clover. 
Often a part of the wheat field is plowed after harvest, disked, har- 
_rowed, and rolled. This process is called summer-fallowing. In 
the fall redtop, sometimes with timothy, is sown along with the 
wheat. The general practice is to sow clover in the early spring. 
Sometimes clover alone is sown on the wheat land and left to hold 
the ground only one year, when it is turned under and followed by 
corn or tobacco. If grasses are sown with the clover and make a 
good stand, the land may remain in sod two or three years for 
meadow or pasture. When clover is cut for hay a second growth 
comes on, which, if the season is favorable, is cut in the fall for seed. 
It will thus be seen that the problem of rotations in this locality 
is very complicated. Instead of the system becoming a mechanical 
one, as is the case in some sections, the farmer here modifies it each 
year to suit such conditions as may prevail at the time of prepara- 
