42 BULLETIN 174; TJ. Si DEPARTMENT OF AGRICULTURE. 
and not the record of a completed and perfected outfit. Further- 
more, most of these tractors have been operated by men who were 
not properly trained and equipped to handle them efficiently, and 
during the first few years of the development of the gas tractor the 
machines placed on the market were mainly large outfits, which were 
necessarily expensive, and failure meant a heavy financial loss. 
It is generally recognized that the gas tractor was of great value 
in rapidly breaking up large areas of prairie sod in the West at a time 
when horses were not available, but after the sod was broken they 
proved an unprofitable investment for the individual farmer in a 
large percentage of cases. A few owners have found the tractor a 
very profitable investment, doing its work more satisfactorily and 
much cheaper than could be done with horses, while a great many 
discontinued its use after a trial. 
The percentage of owners reporting favorably regarding the tractor 
decreases with the length of time they have used their outfit, due 
partly to the fact that the older machines were not as good as the 
later ones, but mainly to a better realization of the tractor's value 
in their work. 
As would be expected, owners who report unfavorably regarding 
the tractor obtain poorer average results than those who state that 
the tractor is a good investment. The repair charges reported by 
both classes of owners indicate that this is due to a considerable 
extent to less efficient operation by the owners reporting unfavorably. 
The average life of a tractor as estimated by owners in North 
Dakota is about six years, while the average life as estimated by 
owners in States other than North Dakota is about eight years. To 
judge by the small percentage of reports received for tractors three 
or more years old, it would appear that a large number of outfits 
three, four, and five years old are no longer in use, indicating that 
the average life is even less than six years. 
The plowing done with tractors has been little, if any, deeper than 
that done with horses. 
Combination work is not practiced to a great extent and usually 
is limited to harrows or drags after the gang plow. 
The percentage of tractors which are operated at night is com- 
paratively small, varying from 11 to 14 per cent, although the 
tractor's efficiency at night is very good. 
No injurious packing of the soil is caused by the tractor's wheels 
if the soil is in proper condition to be worked. 
The item of repairs has been one of considerable importance in 
connection with the use of farm tractors, but the data indicate that 
a large percentage of such repairs have been caused by inefficient 
operation. 
