John Van de Vegte, Engineering Specialist, BMP Technical Integration & Transfer, OMAFRA
Tree fruit production throughout the year can be broken down into a number of separate operations. Some of these operations, such as pruning, thinning and harvest, make up the majority of the annual labour cost for each orchard.
All orchard have different layouts, age and production practices that have an impact of the overall labour production cost. It is useful to be able to measure the actual labour cost and productivity at each orchard. This data can be used to:
- Compare actual labour cost and productivity for orchard operations to industry averages which can be found in the OAG 2016 Ontario Apples Establishment and Production Costs. Orchards with higher labour costs per operation than the industry average should consider making process changes in their production operations to reduce their cost of production.
- Set a baseline to be used to determine the cost-benefit analysis of trying out new production practices or equipment.
The labour quantification methods described below and in the accompanying MS Excel spreadsheet are in general use in manufacturing industries in Canada and can be applied to orchard operations.
Labour Time Study
This labour quantification method is used to measure labour productivity and labour cost for individual operations such as pruning, thinning and harvest.
In general, the Labour Time Study measures the time and labour required to complete at least 10 cycles of a particular operation.
The data collected throughout the operation cycles are:
Head Count: How many operators are conducting the work being measured?
# Operation Cycles: How many operation cycles are being tested?
Total Test Time: How much time is used to complete the operation cycles?
Labour Rate: How much is each Operator being paid per hour?
With this information in hand, the following operation parameters can be calculated:
Productivity is a measure of how many operation cycles are completed per hour. Units for orchard operations would be Trees / Hour or for harvesting, Bins/Hour.
Labour / Tree is a measure of the average total labour consumed per operation. Units are in Man-Seconds / Tree.
Labour Cost / Tree is the average labour cost consumed per operation. Units are in $ / Tree.
Labour and Labour Cost parameters can also be calculated on a per acre basis by taking in account the number the trees per acre.
Here is a pruning example for illustration purposes:
2 Operators paid a total labour rate of $15.40/hr are able to prune 12 apple trees in 30 minutes. They are pruning a high density block with 1,200 trees per acre.
Productivity = 12 trees / 30 minutes = 0.4 trees/minute = 24 trees/hr
Labour / Tree = [(30 min x 60 sec/min) x 2 operators] / 12 trees pruned = 300 man-sec / tree = 0.083 man-hr / tree
Labour Cost / Tree = 0.083 man-hr/tree x $15.40 /hr = $1.28 / tree
Labour / Acre = 0.083 man-hr/tree x 1200 trees / acre = 100 man-hrs/acre
Labour Cost / Acre = $1.28 / tree x 1200 trees / acre = $1,540 / acre
Time and Motion Study
Harvesting in an orchard is a complex operation made up of multiple Operators completing a number of activities concurrently. The simple example of an Operator harvesting apple trees from the ground, each harvest operation cycle is made up of:
|1||Walk from bin to tree|
|2||Fill bag with apples|
|3||Walk from tree to bin|
If the Operator was picking apples using a ladder, you can include an activity for moving and climbing up the ladder.
Optimizing the Operator productivity would be achieved by maximizing the amount of time he or she is filling the bag with apples and minimizing the duration of the other non-value add activities. A Time and Motion Study is used to breakdown the average time spent completing each operation activity.
In general the study consists of starting a stop watch at the beginning of an operation cycle and documenting the time each activity is completed. Continue collecting the activity end times for at least 4 complete operation cycles for each Operator being measured. The duration for each activity can then be calculated from the collected activity end times. Accumulate the activity times to determine the % of total operation cycle time being consumed by each activity.
In order to reduce the cost of production, effort should go into reducing the time being spent by the Operators on non-value add activities i.e. moving to and from the tree.
Here is a Time and Motion Study using the following collected data:
|Activity||Stop Watch Time at End of Activity|
|1||Move to Tree||0:00:05|
|3||Move to Bin||0:02:42|
|5||Move to Tree||0:03:10|
|7||Move to Bin||0:05:15|
The duration for each activity is calculated by subtracting the activity end-times:
|Activity||Stop Watch Time at End of Activity||Activity Duration (sec)|
|1||Move to Tree||0:00:05||0:00:05|
|3||Move to Bin||0:02:42||0:00:07|
|5||Move to Tree||0:03:10||0:00:12|
|7||Move to Bin||0:05:15||0:00:08|
|Accumulated Activity Time||Total Time / Activity||% / Activity||# Operation Cycles||Average Time / Activity|
|Move to Tree||0:00:17||5.25%||2||0:00:09|
|Move to Bin||0:00:15||4.63%||2||0:00:08|
Total Time / Activity is calculated by adding up the duration of times for all the same activities.
The % / Activity can then be calculated indicating the percentage of the total operation time being spent in each activity.
The # of operation cycles measured during the Time and Motion Study can be used to calculate the Average Time / Activity.