I o 
Colorado Experiment Station. 
limited number of years in which records have been kept can be 
given for such crops. Every item of expense and every operation 
performed upon a specific crop has been taken into account in work¬ 
ing up these costs; consequently from year to year the items in the 
tabulated statements will vary somewhat, because in some years a 
certain operation was performed which was not performed in all 
of the other years. In determining the amount to legitimately 
charge the fields on account of machinery used, the following meth¬ 
od was pursued. We can illustrate this method by taking one or 
two specific instances. In the case of plowing, to determine the 
machinery cost of plowing in a specific year, the total value of the 
plows used was taken as a basis. This total value was charged 
interest and depreciation. The interest, depreciation and repairs 
were considered to be the total machinery cost for plowing for the 
particular year under consideration. To get the amount to charge 
to any specific crop, the total number of acres upon which plows 
were used was divided into the total machinery cost of plowing. 
This would give the cost per acre. A charge was then made for 
the machinery cost based upon the acres which a particular crop 
occupied for a given year. 
These costs are summarized in Table No. 3. In this table are 
given the entire cost and number of acres upon which the machine 
was used in each of the four years The total cost and the acre cost 
are shown for each of the different machines used. In making up the 
machinery cost for any particular crop a total is taken of the sepa¬ 
rate machines used in the production and harvesting of that crop. 
Those machines which do not enter into the production of the crop 
in any way are not considered in computing the machinery cost of 
the crop. Here again, it will be noticed that the overhead charge 
for machinery is much greater proportionately where the acreage 
upon which the machine is used is relatively small. The greater the 
acreage which the machine is made to cover in a given season, the 
lower the machinery cost per acre. As previously stated, it is con¬ 
sidered that the annual cost of farm machines consists in the sum of 
its depreciation, interest and repairs. 
The same method in principle was followed with the use of 
irrigation water. The total cost of water was divided by the num¬ 
ber of acres upon which water was used which would give the acre 
charge. In this instance the method had to be varied slightly be¬ 
cause some fields were only irrigated once, while others were irri¬ 
gated three times. A unit charge per acre was worked out for a 
single irrigation. Where a crop received three irrigations, three 
times the unit charge was placed against the crop. 
