MACHINERY COST OF FARM OPERATIONS. 
11 
at all. The total cost of repairs during the life of the spike-tooth 
harrow in this section amounts to only 20 per cent of the first cost 
of the implement. 
THE DISK HARROW. 
The disk harrows used in western New York (Table VI) show an 
average of 13 years, 457 acres, and 54 days of actual work. The 
9-foot disk harrow, working 99 acres annually, as compared with a 
5J-foot disk harrow, covering 16.7 acres annually, or one-sixth as 
much, lasts only two years less, covers five times as much land before 
wearing out, and works four times as many days. The cost of the 
larger implement exceeds that of the smaller by only 25 to 30 per 
cent. The farmer who has the greatest use for a disk harrow obtains 
the greatest return per day and per acre on his investment. 
The depreciation charge against the disk harrow averages $0,059 
per acre and the interest charge $0,025 per acre. The disk harrow 
is a much more expensive implement per acre than is the spike-tooth 
harrow or the spring-tooth harrow. Farmers who can use the larger 
disk harrows drawn by larger teams working over large acreages 
annually are seen to have a very great advantage economically in the 
matter of overhead charges. 
Table VI. — Dish harroivs — relation of work done annually to service and cost -per acre 
and per day used on 738 farms. 
Range of area covered annually acres. . 
Number of records included 
Average area covered annually acres. . 
Years of service rendered 
Acres covered during life 
Days actually used during life 
Average width of harrow feet. . 
Cost when new 
Total cost of repairs during life 
Total interest during life, at 6 per cent 
Total of depreciation, interest, and repairs during life 
Cost of disk harrow: 
Per day used 
Per acre disked 
26 to 50. 
51 and 
over. 
Average. 
374 
16.7 
13.8 
230.5 
30 
5.5 
S25.00 
5.80 
11.18 
SI. 40 
.182 
271 
38.8 
12.4 
481.1 
55 
6.8 
93 
99.0 
11.7 
1,158.3 
121 
9.0 
*2S. 00 
5.83 
11.28 
$32. 00 
10.30 
12. 17 
54. 47 
$0.82 
.094 
SO. 45 
.047 
35. 2 
13. 
457. 6 
54 
6.4 
$27. 00 
6. 50 
11.31 
$0. 83 
.098 
Disk harrows are operated in this section at an average cost of 
$0,014 per acre for repairs. From Table VI it appears the total 
amount of repairs during the life of the average 6-foot disk harrow 
is $6.50, or about 24 per cent of the first cost of the machine. 
THE LAND ROLLER. 
The land roller is an implement which is subjected to a minimum 
of wear in use. From Table VII it is seen that a roller that covers 
2,100 acres lasts nearly as long as one that covers less than 500 acres. 
