AN APPRAISAL OF POWER USED ON FARMS 19 
corners, for resting the work animals when this t}^e of power is 
used, and for making repairs and adjustments when necessary to 
the machinery or equipment used. 
Table VII gives a summary of the work factors or time required 
for performing field work. The time required for performing the 
majority of farm operations with power units oi different size 
and under various conditions is shown in detail in the 1922 Year- 
book of the United ^tates Department of Agriculture, under the 
title of ^^Farm Operations/' and also in Yearbook Separate No. 890. 
POWER AND LABOR REQUIREMENTS OF FARM COMMODITIES 
The amoimt of power and labor required in the production of 
any farm commodity obviously depends upon the requirements of 
the different operations performed. For this reason an even greater 
variation exists when considering the rec[uirements of commodities 
than in the case of the individual operations, and any figures given 
should be taken as no more than a rough approximation when con- 
sidered in respect to any particular case. 
As a matter of general interest rather than as a guide in consider- 
ing specific conditions. Tables VIII and IX have been prepared, 
showing the approximate average number of man-hours and horse- 
power-hours required for the production of the principal crops pro- 
duced in various parts of the United States; Table X shows the ap- 
proximate average labor and power requirements for the care of 
livestock. A more complete discussion of such requirements of field 
crops may be found in United States Department of Agriculture 
Bulletin 1000, Labor and Material Kequirements of Field Crops. 
Table XI gives, hj States, the acreage of the principal crops 
grown in 1922, as reported by the division of crop and livestock 
estimates. Bureau of Agricultural Economics, United States De- 
partment of Agriculture; Table XII gives the average yield of the 
principal crops for the years 1918 to 1922; and Table XIII the num- 
ber of each of the principal kinds of livestock kept on farms, as re- 
ported January 1, 1920, by the Bureau of the Census.® 
DISTRIBUTION OF FARMS AND FARM LANDS AND TYPES AND 
SIZES OF FARMS 
The types of farming followed and the sizes of farms vary con- 
siderably in different sections of the United States and even in indi- 
vidual communities in the same section. The most comm^on type of 
farming foUow^ed in any given locality usually depends upon a num- 
ber of factors, chief among which are geographical location •with. 
respect to nearness to consuming centers and the transportation 
facilities available, the length of the growing season and the amount 
and dependability of the rainfall, type and fertility of the soil, 
and the topography. Table XIV gives the total population, the 
farm population, the number of agricultural workers, the number 
of farms, the total land area, and the land in farms by States, based 
on the 1920 census. Table XV gives the average crop-acres and 
9 The distribution of each of the various crops and kinds of livestock is shown graphically in the 1921 
Yearbook of the United States Department of Agriculture and in Yearbook Separate 878, "A Qraphiq 
Summary of American Agriculture." 
