54 
BULLETIN 
TJ. S. DEPARTMENT OF AGRICULTURE. 
COST OF POWER FOR DIFFERENT OPERATIONS AS FURNISHED BY 
HORSES AND BY TRACTORS. 
The cost per acre of power during the year covered by the investi- 
gation for the different operations for which both horses and tractors 
were used on these farms is shown in Table 42. The costs based on 
present prices (Sept., 1921) of feed, fuel, and oil are also shown. 
The 1920 cost per acre of power furnished by horses is given on 
page 45. The 1921 horse costs are based on an annual cost per head 
of $85 for keeping workstock, or $1.29 per day of horse labor (see 
page 45). The 1921 tractor costs are 82 per cent of the 1920 costs. 
(See page 51). 
Disking in combination, i. e., drawing a disk and a harrow or roller 
at one operation, was not done with horses on any of the farms, and 
the cost of power for harrowing and rolling with horses has been 
added to that for disking to obtain a cost comparable to the cost of 
performing the two operations at once with the tractors. 
The cost of power for plowing done with tractors during the year 
of the investigation was only about 70 per cent of that for the plowing 
done with horses, but with the exception of disking in combination 
the cost of power furnished by the tractors for each of the other 
operations was slightly greater than that furnished by horses. These 
figures, of course, represent the cost of power only, and they do not 
include either the cost of man labor or of the implements used for 
the different operations. Neither do they take into account possible 
differences in the quality of work resulting from the use of the two 
sources of power. 
Table 42. — Cost of power for different operations as furnished by horses and by tractors. 
[Cost per acre.] 
Operation. 
1920 
Horses. 
Tractors. 
2-plow. 3-plow. A1J 
1921 
Horses. 
Tractors. 
Spring plowing 
Fallplowing 
Disking 
Disking in combination. 
Harrowing, rolling, etc. 
Drawing hay loader 
Drawing grain binder . . 
$2. 89 
3.04 
.64 
.98 
.34 
.98 
.59 
S2.01 
2.06 
.71 
.71 
.35 
1.14 
.64 
S2.15 
2.22 
.59 
.76 
.49 
1.05 
.76 
S2.07 
2.13 
.67 
.72 
.37 
1.11 
.67 
SI. 53 
1.02 
.34 
.52 
.18 
.52 
.31 
SI. 70 
1.75 
.30 
.91 
.55 
Note.— The cost of man labor and of the implements used must be added to the cost of power to obtain 
the totalcost of performing the different operations. The horse costs shown for 1921 are 53 per cent and the 
tractor costs 82 per cent of the 1920 costs. 
ANNUAL COST OF POWER FOR DRAWBAR WORK. 
Table 43 shows the average cost of the power furnished by the 
2-plow, 3-plow, and all tractors for drawbar work on the home farm 
during the year covered by the investigation. On the average, this 
