MACHINERY COST OF FARM OPERATIONS. 



9 



strain and wear on the working parts than for walking plows. The 

 average sulky plow hi this section works 119 days and plows 250 

 acres of land. Its cost new is over three times that of a walking 

 plow; so that the overhead charges (replacement and interest) are 

 five or six times as much per acre and over five times as much per 

 day. The quality of work done by the sulky plow when properly 

 operated is sufficiently superior to offset the greater overhead charges. 



The decrease in cost per acre with increase of annual use show very 

 conclusively the advantage of covering large acreages per plow 

 annually. 



The man with a small acreage may reduce his replacement cost 

 somewhat by buying a lighter plow at a lower price, but even this 

 docs not eliminate the economic disadvantage under which he labors. 



Sulky plows have a higher average repair charge per acre than do 

 walking plows, the average being $0,069. The sulky plows in general 

 use cost from $40 to $45, so that the total repair charges during life 

 average 42 per cent of the first cost of the implement. The repair 

 charges decrease as the acreage plowed is increased, this being in 

 part accounted for by the larger plows used on the greater acreages. 



THE SPRING-TOOTH HARROW. 



In Table IV is shown the performance of spring-tooth harrows. 

 The spring-tooth harrow is an implement that gives long service in 

 years and also in terms of acres harrowed. Because of the large 

 areas covered daily, its life in days actually worked averages only 73. 

 The spring-tooth harrow is an implement that is given very poor 

 shelter, its form making it awkward to house, and it often lies out 

 unprotected from one year's end to another. The repair charges on 

 these harrows are also very small. From the standpoint of work 

 done it is a machine of very high efficiency, averaging 1 1 years of life 

 and 782 acres of work. Table IV, like all of the other tables, shows 

 that the larger machines winch do the most work annually also do the 

 greatest total of acres and days before being worn out. 



Table IV. — Spring-tooth harrows— relation of work done annually to service and cost 

 per acre and per day used on 1,169 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 spring-tooth harrow: 



Per day used 



Per acre harrowed 



1 to 40. 



81 to 150. 



151 and 

 over. 



417 



29.5 



11.6 



342.0 



39 



5.7 



61.0 



11.1 



577.1 



74 



6.5 



276 



111.6 



10.2 



1, 138. 3 



96 



■ 8.2 



68 



222.3 



8.9 



1,978.5 



149 



10.4 



71.1 

 11.0 



782.1 



73 



6.9 



$15. 00 

 6.15 

 5.92 



27.07 



$17.00 

 8.88 

 6.22 



$20. 00 

 9.28 

 6.73 



$24. 00 

 10.86 

 8.16 



$17. 50 

 8.25 

 5.83 



43.02 



0.794 

 .079 



$0. 433 

 .047 



$0. 375 

 .032 



0.2S8 

 .021 



0.432 

 .043 



13345°— Bull. 338—16- 



