80 BULLETIN 1271, U. S. DEPARTMENT OF AGRICULTURE 
require different amounts of man labor, horse labor, land, and manage- 
rial ability for a given volume of product. For example, on 18 farms 
in 1921 averages of 19 hours of man labor and 42 hours of horse labor 
per acre were used in the production of corn. On the same farms, 
averages of 7 hours of man labor and 16 hours of horse labor were 
used in the production of oats. Likewise, the different kinds of live- 
stock require varying amounts and qualities of labor, feed, shelter, 
and other requirements. 
There are also wide variations in the time at which and the periods 
during which these various requisites are demanded by the different 
kinds of crops and livestock. Most crops require attention only at 
certain definite seasons of the year and these seasons are different for 
the various crops. For example, the seed-bed preparation and 
seeding of oats are ordinarily completed several days before the time 
for final preparation and planting of corn. Then late in July after 
the corn cultivation is completed comes the oat harvest. Thus 
the labor, horses, and machinery of the farmer are usually employed 
more economically in a system of diversified farming than in a single- 
crop system, even if the crop needing attention at one time gives a 
lower return than that requiring attention at another time. 
On some crops the labor is used in more or less regular amounts 
over a long productive period. In some cases, notably with the 
small-grain crops, the work comes in two or three short periods of 
seed-bed preparation, planting, harvesting, and threshing. Crops 
which require attention at the same time of the year may be regarded 
as competing crops. The spring grains — oats, barley, and spring 
wheat — are examples of competing crops in this area. They re- 
quire about the same amount of man labor, horse labor, and tools 
at approximately the same time. 
One enterprise is complimentary to another when it makes a defi- 
nite contribution to it. Crops and livestock are frequently mutually 
complimentary, the crops furnishing feed for the livestock and the 
livestock in turn furnishing fertility for the crops. Complementary 
relations are evident between legumes and other crops included in a 
rotation. The legumes help to ouild up the soil for the production 
of the other crops in the rotation, and frequently the legumes re- 
ceive protection from the small grain when used as a nurse crop. 
Supplementary enterprises are frequently brought in to reduce the 
burden of expense of the enterprises supplemented. The supple- 
mentary enterprise may reduce the idle time, idle land, idle machin- 
ery, etc., left over after the major enterprises have been properly con- 
ducted. The object is always to get the fullest utilization of the 
requisites of production, and since such an enterprise utilities sup- 
plies of labor and nonmarketable feeds which would otherwise be 
wasted, it may give a relatively low return and still be profitably in- 
cluded in the farm organization. 
The demands of different crops and kinds of livestock frequently 
conflict in certain respects, although they are complementary or 
supplementary in other respects. Corn and alfalfa compete for labor 
during corn cultivation in June and frequently again at silo-filUng 
time. However, the silage and alfalfa are supplementary as dairy 
feeds and this may more tnan compensate for the conflicting demands 
for labor. These conflicting, complementary, and supplementary 
relationships of enterprises are not susceptible of exact measurement. 
