Title: Cost of operating farm tractors in Columbia and Suwannee counties
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Title: Cost of operating farm tractors in Columbia and Suwannee counties
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Creator: Greene, R. E. L.
Publisher: Department of Agricultural Economics, Florida Agricultural Experiment Station
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Agricultural Economics Mimeograp Report No. 58-2


COST OF OPERATING FARM TRACTORS IN COLUMBIA

AND SU0TANNEE COUNTIES






BY


R. E. L. GREENE
Agricultural Economist


TABLE OF CONTENTS


Introduction . a. . .
Purpose and Procedure .. ......
Definition of Terms ... ... .
Amount of Annual Use, Age and Value of Tractors .
Variations in amount of annual use . .
Average Cost of Operating Tractors .. .. ....
Estimated life and cost of tires and batteries .
Cost of operating tractors by type of fuel ..
Relation of Size of Load to Cost . . .. .
Relation of Amount of Annual Use to Cost . .


* C C
C C a
* C S
C C C
* C 5
* C C

* C C
C 9 a
* a C


Rate of Work per Day, Amount Performed and Days Operated at
Various Uses *. . . . . 11
Value per Unit and Average Value of Tractor Equipment 13
Summary . . . ..... 15









Department of Agricultural Economics -
Florida Agricultural Experiment Station /
Gainesville, Florida '


Seiplheber, 1957










COST OF OPERATING FARM TRACTORS IN COLUMBIA AMD SU ANNEE COUNTIES


Introduction

In 1920, there were only 680 tractors operated on Florida farms
(Fig. I). The number has increased rapidly since that time but the
greatest rate of growth has been since 1940. The 1954 census of
agriculture reported 34.,821 tractors on Florida farms. A farm ma-
chinery trade journal, "Implement and Tractor", estimates that the
1965 figure should exceed 50,000.

The increased use of farm tractors and other farm equipment has
increased the interest in data on cost of operation. Such data are
of importance to the farmer who is shifting his type of power or who
desires to reduce his power costs. Since the average farmer does not
keep the necessary records for calculating his own costs he must depend
on data from other sources. A knowledge of the various items of ex-
penses is necessary before intelligent cost reduction measures can be
effected.

Persons who plan farming ventures or farmers who contemplate an
expansion in farming activities need factual information on costs in
order to anticipate with reasonable accuracy the costs involved and
also to guide them in making selections of equipment.

Purpose and Procedure

The purpose of this report is to present data on the amount of
use and cost of operating tractors in Columbia and Suwannee counties
in 1952. Data on tractor operation were collected from farmers in
these counties in 1953 as part of a study, "Effects of Enterprise
Adjustments and Improved Management Practices on Farm Incomes in
North Florida." Records were obtained for 132 farms selected to
represent the agriculture of the two counties. There were 101 tractors
on these farms. Some were tractors more than 12 years old. Others
were purchased during the year so the records did not include a
complete year's operation. These two groups were excluded from this
analysis. Records for 91 tractors were included in this summary.

The data collected'gave the make, model and year of each tractor.
An estimate was obtained from the operator of the fuel and oil used
per 10 hour day when the tractor was used for light, medium and heavy
work. Data were also obtained on the annual costs for repairs, tires,
batteries and other items. De, reciation was based on the difference
between the farmers estimate of t'e value of the tractor at the be-
ginning and end of the year. Annual use was calculated based on the
estimated time required to perform the various jobs on which each
tractor was used during the year. Cost per hour was obtained by
dividing the total cost for the year by the number of hours operated.







-2-


No. of Tractord /

L8, 000
/
L0,000 /

32,000-

2, 000-i

16,000o

8,000,


1920 1930 1940 1950 1960i


Fig. 1.-- Trend in number of tractors in Florida, 1920-1960.

The tractors were classified into four size groups based on draw-
bar horsepower rating as determined in Test H of the Nebraska Tractor
Tests._/ Tractors rated 6.0 to 12.0 drawbar horsepower were classified
as small; those rating from 12.1 to 16.0, intermediate; 16.1 to 22.0,
medium, and those rating 22.1 or more, large. The tractors were also
sub-grouped as to those using gasoline or distillate as the principal
fuel. None of the tractors for which records were obtained fell in
the large size group.


I/See Summary of Results of Nebraska Tractor Tests Selected
Reports, University of Nebraska, Department of Agricultural Engineering.







-3-


Definition of Terms

Certain terms used throughout this report are explained as follows:

Farm tractor: Any wheel type tractor used primarily for field
worko
Size of tractor: Four size groups classed according to drawbar
horsepower as rated in the ten-hour test designated as Test H of
the Nebraska Tractor Tests as follows:

Small 6.0 to 12.0 hp Medium 16.1 to 22.0 hp
Intermediate 12.1 to 16.0 hp Large 22.1 to I4.0 hp

Work day: Ten hours of tractor operation,
Load classification: Loads were classified as light, medium, and
heavy depending on the power required. The decision as to whether
individual operation was classified as light, medium, or heavy
for a particular tractor was that of the operator interviewed.
Operating costs: The sum of all costs for fuel, grease, oil,
repairs, tires, oil filters, and batteries.
Depreciation: Depreciation was the farmer's estimate of the de-
crease in value of the tractor based on the difference between
the estimated value of the tractor at the beginning and end of
the year.
Interest on investment: A yearly cost calculated at 5 percent of
tile average value of the beginning and ending inventory values for
the year.
Overhead or fixed costs: The cost of depreciation and interest on
investment (these costs do not include a charge for taxes, in-
surance, or housing).
Total operating costs: The sum of operating and overhead costs as
calculated above.
Cost per hour of operation: Total operating costs divided by
number of hours operated.


Amount of Annual Use, Age, and Value of Tractors

The amount of annual use for tractors varied by size of tractor
and type of fuel used. Small tractors powered by gasoline were used an
average of 463 hours per year while those powered by distillate were
used an average of 712 hours (Table 1). Intermediate and medium size
tractors were used an average of 758 and 896 hours and 843 and 905 hours
for the two fuels respectively.

The average age of tractors for the different groups varied from
2.2 to 4.6 years. The estimated purchase price and present value of
the tractors increased as the size classification increased. However,
the average cost per H.P decreased as the size of the tractor increased.









Table 1.-- Annual Use, Age, Estimated Life and Purchase Price for 91
Tractors, Columbia and Suwannee Counties, Florida, 1952.


Size classifications
Item : Unit Small :Intermediate : Medium
: :Type of fuel :Type of fuel :Vype of fuel
: :Gaso-:Distil-:Gaso-:Distil-laso-:Distil-
: line: late : line: late s line: late

Tractors Nulber 9". 31 24' 3 11': 13
Average annual use Days 46.3 71,2 75.8 89.6 84.3 90.5
Present age Years 3,5 4.2 3.7 2.7 2.2 4.6
Estimated present value Dollars 678 .967. 1012 10145 1254 1030
Estimated purchase price Dollars 1053 1416 1690 1725 1723 1872
Average horsepower Number 8.32 10.88 14.29 14.77 18.68 18.67
Purchase price per H.P. Dollars 12.66 13.01 11.83 11.68 9.22 10.03


Variation in amount of annual use.-- There was a wide variation in
amount of annual use for tractors on individual farms. In the case of
small tractors, the average amount of annual use was 65.6, 10-hour days
(Table 2). However, 42.5 percent of the tractors were used less than
50 days and 17.5 percent 100 days or more. In the intermediate size
tractor group, the average annual use was 77.3 days but 22 percent were
used 100 days or more and 15 percent less than 50 days. Medium size
tractors were used an average of 87.6 days per year with one-third of
the tractors being used 100 days or more.


Average Cost of Operating Tractors
The average cost of operating a tractor for a 10 hour day ranged
from 59 cents per hour for small tractors to 73 cents per hour for
medium size tractors (Table 3). This amount included direct or operating
cost and overhead' or fixed cost. Operating cost was influenced by the
type of work and size of tractor. The fixed cost was influenced princi-
pally by the number of ddys used annually and the average life and the
purchase price of the tractor.

In the case of small tractors, total cost was divided almost
equally between operating and fixed cost. In the intermediate and
medium size tractors, operating cost made up 64 and 60 percent respectively
for the two groups. In the case of both intermediate and medium size
tractors, fuel was the most important item of cost and depreciation
second. For the small size tractors, depreciation was the largest item
of cost and fuel second.









Table 2,-- Variation in Days of Annual Use by Size of Tractor, 91
Tractors, Columbia and Suwannee Counties, Florida, 1952.


S Type of fuel Afl tractors
Days of annual use .
DGasoline Distillate: Number : Percent
*


Small Tractors


Less than 40
40-49
50-59
60-69
70-79
80-89
90-99
100 or more
Total
Average number


Less than 40
40-49
50-59
60-69
70-79
80-89
90-99
100 or more
Total
Average number


of days of use


-4i
46.3


4
6
6
4
2

2
7
71,2


Intermediate Tractors


of days of use


2
1
4
4
3
4
2
4

75.8


2
89,6
89.6


Medium Tractors


Less than O0
40-49
5o-59
60-69
70-79
80-89
90-99
100 or more
Total
Average number of days of use


1
1
2
2
2

ril
84-3
814.3


15.0
27.5
17.5
12.5
5.0


2

65.6


7;4
7.4
7;8
14 8
14.8
11.1
14,8
22.3
10000


2
2
4
4
3
4
2
6
77.3
77.3


2
1
1
1
1

90.5


8.3
4.2
12,5
12.5
12.5
4.2
12.5
33.*
L6


2
1
3
3
3
1
3
8

87.6


.








-6-


Table 3.-- Average Cost of Operating Small, Intermediate and Medium
Size Tractors per 10 Hour Day, 91 Tractors, Columbia and
Suwannee Counties, Florida, 1952.


S Average cost Percent of total
Item 'Inter- : :Inter- :
ISmall :mediate;Medium :Small mediate;Medium

Number of tractors 40 27 24
Days of annual use 6$.6 77.3 87.6
Cost per :10 hour. day
Operating cost:
Fuel $1.72 $2.91 $2.73 29.1 42.8 37.3
Motor oil .27 .20 .29 4,5 3.0 4.0
Grease ,07 .07 .09 1.2 1.0 1.2
Oil filters .08 .08 .09 1.3 1.2 1.2
Repairs and overhaul .20 .28 .37 3,4 4.1 5,1
Tires:
Front .10 .13 .15 1.7 1.9 2.0
Rear .39 .49 .54 6.6 7.2 7.4
Batteries .15 .19 .17 2. 2.8 2.3
Total T"9 "T 50.5 64~0 60-.
Overhead cost:
Depreciation 2.24 1.79 2.24 37.9 26.3 30.6
Interest 70 .66 .65 11.8 9.7 8.9
Total "9 M45 89 "49.7 36-0 19

Total cost per 10
hour day 5.92 6.80 7.32 100.0 100.0 100.0

Estimated life and cost of tires and batteries.--Cost of tires and
batteries made up about one-fifth of the operating cost of tractors in
each size group. The annual charge for each of these items was cal-
culated based on their estimated life and replacement cost. The life
of a battery was estimated at 23 months for a small tractor and 15
months for a medium size tractor (Table 4). The cost of batteries was
estimated at about $17.
There was very little difference in the estimated life of front
and rear tires for tractors in the same size group. However, the
estimated life of tires for small tractors was about one year more than
the estimated life of tires on tractors in the medium size group. Esti-
mated cost of front tires for tractors in the three size groups did not
vary greatly. The cost of rear tires for small tractors was estimated
at $60.10 compared to $80.08 for rear tires for tractors in the medium
size group,










Table 4.--


Estimated Life and Cost of Batteries and Tires, byr Slae of
Tractor, 91 Tractors, Columbia and Suwannee Counties,
Florida, 1952.


t Tractor classification
Item
: Small : Intermediate: Medium

Battery:
Estimated life (months) 23 16 15
Cost new $17.40 $16.14 $17.56
Tires:
Estimated life (years)
Front 5.3 4.3 4.3
Rear 5.6 4,4 4.0
Cost new:
Front $15.20 $18.06 $16.83
Rear 60.10 71.11 80,08


Cost of operating tractors by type of fuelb-- The cost of oper-
ating a tractor is affected by the type of fuel used. In the case
of small and medium size tractors, a sufficient number of records were
obtained for tractors operating on gasoline and distillate to summarize
the cost for each group. For small tractors, operating cost was 4.4
cents less per hour for tractors burning distillate than for those
burning gasoline (Table 5). The difference in the total cost for these
two groups was greatly affected by the amount of use. Operating cost
for medium size tractors burning distillate was 5.8 cents less per
hour than those burning gasoline (Table 6). The overhead cost on the
group burning distillate was estimated to be 24 percent lower than the
group burning gasoline. The difference in amount of annual use be-
tween the two groups was only 7 percent.









Table S.-- Average Cost
40 Tractors,


-8-

of Operating Small Tractors per 10 Hour Day,
Columbia and Suwannee Counties, Florida, 1952.


: ~ype of fuel
Item Unit Gasoline : Distillate
:Unit : :Unit : :
: :price:Amount: Cost :price:Amount: Cost


Cents
Number of tractors
Days worked per year
Cost per 10 hour day:
Operating costs:
Fuel:
Gasoline Gal. 25.6
Distillate Gal.
Motor oil Qt. 22,9
Grease Ib. 22.4
Oil filters No. 51.4
Repairs & overhaul
Tires:
Front
Rear
Batteries
Total operating cost
Overhead cost:
Depreciation
Interest
Total overhead cost
Total cost per 10 hour day
Cost per hour


.Centsj
9
46.3


8.24 $.ll 25.8
15O0
1,22 .28 24.2
,25 .06 23.3
.13 .07 89,5
.10


.93
9.34
1.11
.32
.09


.12
.40
.21
3.35
2.88
.80

7.03
.70


31
71.2


$ .24
1,40
.27
.07
,08
.22


.10
.39
.14


2.12
.68

5.71
.57










Table 6.-- Average Cost of Operating Medium Size Tractors per 10 Hour
Day, 24 Tractors, Columbia and Suwannee Counties, Florida,
1952.


m : Type of fuel
Item :Unit(
: : Gasoline : Distillate
: :Unit : : :Unit :
: price:Amount :Cost :price:Amount :Cost
Cents Cents
Number of tractors 11 13
Days worked per year 84.3 90.
Cost per 10 hour day:
Operating costs:
Fuel:
Gasoline Gal. 25.0 11.97 2.99 25.0 .68 o17
Distillate Gal. 1619 15.80 2,35
Motor oil Qt. 28,4 .90 .26 24.7 1.25 .31
Grease lb. 23.2 ,51 .12 27.6 *25 .07
Oil filters No. 126.1 .08 .10 100.9 .08 .08
Repairs and overhaul .46 .31
Tires:
Front .12 .16
Rear .53 .56
Batteries .18 .17
Total operating cost 1. r1
Overhead costs:
Depreciation 2.58 1.96
Interest .74 .57
Total overhead cost 3.32 253
Total cost per 10 hour day 8,08 6.71
Cost per hour .81 .67


Relation of Size of


Load to Cost


The type of load was an important factor affecting the cost per
hour of operating the tractors. As indicated on page 1, the operators
estimated the variation in fuel and oil consumption for light, medium,
and heavy work. Assuming no variations in other cost per hour by type
of work, the cost of operating a small tractor was 52 cents at light
work and 62 cents at heavy work (Table 7). The cost per hour of an
intermediate size tractor varied from 64 to 72 cents and medium size
tractor from 69 to 77 cents for light and heavy work respectively.

Operators interviewed also classified the jobs performed by each
tractor as to whether they considered the load light, medium or heavy.
The proportion of the operating time in various work classifications was







-10-


about the same for each size tractor. Roughly, about one-fourth of the
time was spent at light and heavy work and one-half of the time at jobs
classified as a medium load.


Table 7.--


Cost per Hour of Operating Tractors and Proportion of Time
Used for Light, Medium and Heavy Work by Tractor Classi-
fication, Columbia and Suwannee Counties, Florida, 1952.


: Tractor classification
Size of load : :
: Small : Intermediate : Medium

Cost per hour of operating tractors

Cents Cents Cents

Light 52.3 64.3 69.0
Medium 58.8 67.8 73.2
Heavy 62.3 72.2 77.1
Average cost, all loads 59.2 68.0 73.2

Proportion of time used in various work classifications
Percent Percent Percent

Light 24.4 26.1 26.4
Medium 52 4 48.8 45.3
Heavy 23,2 25.1 28.3
Average days, all loads 65.6 77.3 87.6


Relation of Amount of Annual Use to Cost


The effect of the amount of annual use on the cost per hour of
operating tractors is shown in Table 8. The cost per hour of operating
a small tractor decreased from 83.9 cents to 43.7 cents iihen annual use
increased from an average of 40.6 days to 107.1 days. In the case of
medium size tractors, those with average annual use of 52 days had a
cost of 90.1 cents per hour compared to 66.8 cents for those with an
annual use bf 131.1 days.

The big factor causing cost per hour to decrease as annual use
increased was the reduction in overhead cost. For small tractors over-
head cost per hour for those with the largest amount of use was only
about one-third as great as those with the smallest amount of use. For
intermediate and large size tractors, overhead costs decreased about
50 percent as the amount of use went from low to high.










Table 8.-- Relation of Amount of Annual Use to Cost per Hour of Oper-
ating Tractors, Columbia and Suwannee Counties, Florida, 1952.


S: 'Average cost per hour of operation
Days of :Number of : Average days:
annual use : tractors :of annual use:Operating : Overhead : Total
: : : cost : cost : cost

Small Tractors
Less than 50 17 40.6 35.4 48.5 83.9
50-69 11 58.9 29.7 33.8 63.5
70 & over 12 107.1 26.8 16.9 43.7

Intermediate Tractors
Less than 60 8 48.0 43.5 41.0 84.5
60-84 10 73.9 L4.8 21.9 66.7
85 & over 9 107.2 42.3 19.8 62.1

Medium Tractors
Less than 70 9 52.0 48.9 41.2 90.1
70-99 7 83.7 11.4 29.6 71.0
100 & over 8 131.1 43.9 22.9 66.8


Rate of Work per Day, Amount Performed and Days Operated at Various Uses
The amount of work a tractor will do in 10 hours depends upon the
size of the tractor, the speed operated, and the size of the implements
used. Quite often a tractor is not operated at the correct speed. Also,
the size of the implements is not always adjusted to the size of the
tractor as farmers do not always buy new equipment when they buy a
tractor or change size of tractor, Operators should study their business
to determine the best equipment to use and also whether or not jobs can
be combined in order to reduce the cost of power.

The average rate of work per 10 hour day for selected operations
of tractors of various sizes pulling the usual equipment found in the
area is shown in Table 9. As is to be expected, the average rate of
work increased with size of tractor.

In the two counties studied, for each size of tractor, the operation
on which tractors were used the most hours were cultivating and breaking
land. Cultivation accounted for 37 percent of the annual use for small
tractors, 33 percent for intermediate tractors and 29 percent for medium
tractors. Breaking land accounted for 22, 18 and 19 percent of the oper-
ating time for the three groups respectively. Pulling a trailer and use
in harvesting required almost a fifth of the total time for tractors in
each size group.






-12-


Table 9.--


Operations Performed, Rate of Work per Day, Average Amount
of Work per Year, Average Days of Use by Operation and Per-
cent of Total Time Devoted to Various Operations, by Size
of Tractor, 91 Tractors, Columbia and Suwannee Counties,
Florida, 1952.


Average amount of : Percent :Average days of use
:work per year, all :of tractors:per year, all
Kind of work tractors :performing : tractors
: :Rate per : : operations: : Percent
:Unit:lO hr.day:Total: :Number: of total


Small Tractors


Land preparation:
Clearing land
Breaking land
Disking
Harrowing
Seeding and
cultivating:
Distributing
fertilizer
Planting
Cultivating
Other:
Harvesting
Mowing
Pulling trailer
Miscellaneous
Total


Acre
Acre
Acre
Acre


Acre
Acre
Acre


.6
5.0
10.6
10.5


6.7
9,2
y'


Acre 1/
Acre 10.2


.9
60.3
38.1
15.4


7.6
51.7
61.8


12.5
100.0
62.5
22.5


80.0
97.5
100.0


6.0 95.0
7.8 15.0
75.0


Intermediate Tractors


Land preparation:
Clearing land Acre
Breaking land Acre
Disking Acre
Harrowing Acre
Seeding & Cultivating:
Distributing
fertilizer Acre
Planting Acre
Cultivating Acre
Other:
Harvesting Acre
Mowing Acre
Pulling trailer
Miscellaneous
Total


1.6
14.6
3.6
1.5


1.1
5.6
24,4
6.2
.8
5.1
1.1
ill


2.4
22.2
5.5
2.3


1.7
8.5
37.2

9.5
1.2
7.8
1.7
100.0


1.4
7.5
13.9
11.6

7.5
10.5
i'

I;,
14.


7.0
106.9
64.5
15.8

8.4
66.3
77.8
6.6
13.7


33.3
100.0
7h.1
22.2

81.5
92.6
100.0

96.3

85.2


5.0
14.3
4.6
1.4

1.1
6.3
25.4

6.6
1.0
7.9
3.7
7 on


6.5
18.5
6.0
1.8

1.4
8.2
32.8

8.5
1.3
10.2
4.8
"T oM








-13-


Table 9.-- (continued)


Kind of work


:Average amount of :Percent :Average days of use
:work per year, all 'of tractors:per year, all
: tractors :performing : tractors
: :Rate per : :operations : :Percent
:Unit:10 hr.day:Total: :Number:of total


Medium Tractors


Land preparation:
Clearing land
Breaking land
Disking
Harrowing
Seeding And
cultivating:
Distributing
fertilizer
Planting
Cultivating
Other:
Harvesting
Mowing
Pulling trailer
Miscellaneous
Total


Acre
Acre
Acre
Acre


Acre
Acre
Acre


1.2
7.9
16.5
22.6


10c4
10.2
1/


Acre I/
Acre 18.0


5.1
134.0
119.7
5.0


11.5
68.7
84.6


20.8
100.0
100.0
8.3


66.7
87.5
95.8


12.1 87.5
38.6 62.5
95.8
66.7


1/ Rate per 10 hour day per time over not obtained.

Value per Unit and Average Value of Tractor Equipment

The number of days a tractor is operated per year depends partly
on the amount and kind of complementary tractor equipment owned by the
farm operator. Table 10 shows the average value of selected items of
tractor equipment far tractors in each size group and also the average
value of equipment per tractor. The value of individual items of
equipment for tractors in the small and intermediate size groups, as
a rule, was about the same. In many cases values of equipment in the
medium size group was greater because the equipment was larger. Equip-
ment such as grain drills, combines and corn pickers were found only
on farms with medium size tractors.

The average value of tractor equipment was $304 for small tractors,
$478 for intermediate size tractors and $1187 for medium size tractors.
Based on the estimated value on December 31, 1952, depreciation for all
tractor equipment was estimated to be 11.2 percent on farms with small


4.1
16.9
7.2
.2


1.1
6.8
25.2

8.2
2.1
9.0
6.8
V77.


4.7
19.3
8.2
.2


1.2
7.8
28.7

9.4
2.4
10.3
7.8
Too,.








tractors, 9.8 percent on farms with intermediate size tractors and 12.5
percent on farms with medium size tractors.

Table 10.-- Average Value per Unit of Selected Tractor Equipment, Value
of Equipment per Tractor and Annual Depreciation, by Size
of Tractor, 91 Tractors, Columbia and Suwannee Counties,
Florida, 1952.


: Tractor classification
Item
: Small : Intermediate : Medium

Breaking plow $ 92 $ 92 $ 148
Tandem disk 106 144 132
Disk tiller 221 209 196
Stalk cutter 47 97 47
Section harrow 69 100 134
Fertilizer distributor 36 35 40
Planter 22 25 39
Cultivator 124 100 145
Mover 132 129 292
Grain drill 274
Combine 733
Corn picker 700
Trailer 51 68 65
Estimated value
December 31, 1952 304 478 1187
Estimated depreciation:
Amount 34 47 149
Percent 11.2 9.8 12.5
Annual repairs 5 16 48








SUMMARY


Data on the cost of operating tractors in Columbia and Suwannee
Counties were collected from farmers in these counties as a part of a
study, "Effects of Enterprise Adjustments and Improved Management
Practices on Farm Income in North Florida". There were 101 tractors
on 132 farms for which information was obtained. Some were tractors
more than 12 years old. Others were purchased during the year so the
records did not include a complete years' operation. These were ex-
cluded and only 91 tractors were included in the summary of cost.

The tractors were classified into four size groups based on drawbar
horsepower rating as determined in Test H of the Nebraska Tractor Tests.
Tractors rated 6.0 to 12.0 drawbar horsepower were classified as small;
those rating from 12.1 to 16.0, intermediate; 16.1 to 22.0, medium; and
those rating 22.1 or more, large. None of the tractors for which records
were obtained fell in the large size group.

The average cost of operating a tractor for a 10 hour day ranged
from 59 cents per hour for small tractors to 73 cents per hour for medium
size tractors (Table 1). In the case of small tractors, total cost was
divided almost equally between operating cost and fixed cost. In the
intermediate and medium size tractors, operating cost made up 64 and 60
percent respectively for the two groups. For both the intermediate and
medium size tractors, fuel was the most important item of cost and
depreciation second. For the small size tractors, depreciation was the
largest item of cost and fuel second.

Operators classified the jobs performed by each tractor as to
whether they considered the load light, medium or heavy. Roughly, about
one-fourth of the time of the various size tractors was spent at light
and heavy work and one-half of the time at jobs classified as a medium
load. Operations on which tractors were used the most hours were
cultivating and breaking land.

The type of load and the days of annual use were important factors
affecting cost per hour of operation. For each size of tractor, cost was
8 to 10 cents per hour more for jobs classified as heavy work compared
to those classified as light work. Tractors used the greatest number of
days per year had a cost per hour only a half to a third as great as
tractors used the least days per year.




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