2 BULLETIN" 338, U. S. DEPARTMENT OF AGRICULTURE. 
acre or per bushel or ton would be constant, but in actual practice a 
machine used but a few days per year lasts only a little longer than 
a similar machine used twice as much. Thus the replacement cost 
per acre depends largely on the number of days per year the machine 
is used. 
From the standpoint of good management, therefore, the farmer 
should try to organize his business so as to obtain the maximum of 
profitable use annually from his machinery equipment, thereby 
reducing the machinery cost per day of work to the minimum. 
The study upon which this bulletin is based was made with a view to 
gathering facts and figures which might be of value to the farmer in 
his efforts to cut machinery cost. To this end figures were obtained 
to determine the average number of years of service given by each of 
the various implements in use in the part of New York where the 
investigation was made, and from the average life of each implement 
and its cost when new the approximate cost of its operation has been 
calculated. 
SUMMARY OF RESULTS. 
Briefly summarized, these are the more important facts brought 
out or substantiated by this investigation: 
The more days' work done annually by an implement the greater 
is its total of days and acres of work done before wearing out. 
The average farm machine used in this section is less than half worn 
out by use alone. 
The more days of actual use obtained annually from an implement 
the less the interest charge per acre and per day actually used. 
The replacement cost per acre or per bushel or ton is from two to 
seven or eight times as great for small acreages as for large acreages. 
The farmer with a small acreage can not compete in economy in 
the use of machinery with the farmer having a larger business. With 
the best of shelter and care, the small farm can only hope to equal the 
replacement cost per unit enjoyed by the large farm; it can not hope 
to avoid higher interest charges. 
As a rule, it is not profitable to build for machinery any special 
shelter which adds over 15 per cent to the total machinery invest- 
ment on a farm. 
Repair charges per machine increase with increasing use, but not 
in proportion to the amount of work done. In other words, repair 
charges per acre and per day decrease as the acreage covered annually 
increases. 
The larger and more substantial sizes of machinery give cheaper 
service than the lighter sizes, since the cost for repairs is much lower 
for the heavy machine than for the lighter machine, while the first 
cost is but a fraction greater. 
