Opportunities to lift harvest efficiency and lower safety risks
Research & ExtensionA US time and motion study highlights some inefficiencies and potential safety risks in conventional manual harvesting practices, finds Gordon Brown.
Apples are still generally commercially harvested by hand. While some harvesting aids such as platforms exist, a large proportion of the crop is still harvested with seasonal labour using ladders and picking bags to deliver the fruit to bulk bins scattered throughout the orchard. With increasing labour costs, labour availability issues and community concerns over workplace safety studying this harvest process in detail enables the identification of inefficiencies and potential risks to pickers wellbeing.
A detailed time and motion study[1] was conducted in the United States to determine typical times spent in picking low, middle and high apples both on the ground and on a ladder, moving the ladder, climbing the ladder, descending the ladder, walking to the bulk bin, emptying picking bags into the bin and walking back to the tree. For the picking activity this study also looked at the time spent moving the arm into the canopy to reach the apple, detaching the apple from the tree and moving the arm back to the picking bag to place the fruit in the bag. In this study four pickers were monitored picking both Gala and Fuji in orchards with a density of close to 2000 trees/ha. The harvest activity was recorded on video and this was used to determine the time spent on each of the activities.
It was found that in the test orchard fruit pickers spent 76 per cent of their time picking apples with the time being equally split between ladder and ground harvesting (Table 1). Moving the ladder, as well climbing it and descending it, occupied pickers for about 13 per cent of their time and the remaining 11 per cent of their time was taken up walking to and from the bulk bin. This data suggests that if a picking platform fitted with a system for moving the harvested apples from the picker to the bulk bin is used, there will be close to a 25 per cent time saving improving picking efficiency.
Table 1: Percentage of time performing each harvest activity
While the pickers spent 76 per cent of their time picking apples it was found that only 30 per cent of this time was spent removing the apple from the tree (Table 2) and about two thirds of the time was spent moving the arm into the tree and removing it again with the harvested apple and placing it in the picking bag. This indicates that harvest efficiency can be greatly improved if the picking bag or the end of the conveyor on a harvest platform can be positioned close into the picking site on the tree. This is a potential advantage of the fruiting wall training system where moving deep into the foliage is avoided and the fruit drop point can be kept close to the fruiting wall. It is also interesting to note that more time is spent reaching into the foliage to the apple than coming back out and placing the fruit in the picking bag. This is probably due to a need to identify a piece of fruit needing harvesting and working out a path to get to the fruit. Again, a fruiting wall should help reduce this ‘thinking’ time improving harvest efficiency.
Table 2: Percentage time spent selecting an apple, picking it and placing it in the picking bag.
In addition to being used to calculate times in any single picking activity, the video was also used to estimate the rapid upper limb assessment (RULA) score to identify the potential ergonomic risk of each activity involved in harvesting apples. These impacts can potentially lead to occupational injuries such as back, neck and shoulder strains, common among seasonal workers. Using this approach, a score over 5 represents a posture safety issue that needs to be managed in order to minimise injuries to pickers and assist in attracting and retaining pickers for the harvest season.
Alarmingly more than half the activities involving in picking apples scored over 5 indicating potential occupational safety risks (Table 3). These included reaching up above shoulder height or bending down to pick low apples, moving an awkward, heavy ladder over uneven terrain and bending down to place a 20kg bag full of apples into a bulk bin.
Many tree training methods can be used to minimise these risks and improve harvest efficiency. The use of dwarfing rootstocks and training to keep the fruiting canopy low will minimise both ladder work and harvesting above shoulder level. Removal of low hanging branches will minimise bending down to harvest these branches. Alternatively, the use of long pendulous low branches that can be lifted with one hand and harvested with the other may also reduce bending. Where trees are planted into hills, the slope may also assist with the harvesting of low branches if they can be reached from the base of the hill. Harvesting apples from a picking platform with multiple height stages eliminates ladders and can minimise reaching high and low to pick an apple. Fitting the platform with a conveyor system to deliver apples from the picker to the bulk bin, reduces both the bending required to empty the picking bag and the time involved.
Given the occupational safety risks associated with traditional hand harvesting of apples picking platforms can be viewed as a piece of safety equipment for pickers with the added benefit of improving picking efficiency. While commercially available picking platforms are expensive and require a large area of apples to justify their purchase, for a small apple grower ‘old fashioned’ hydra ladders also can be used to eliminate many of these risks and inefficiencies. These, along with commercially available picking platforms, reduce the safety risks associated with traditional harvesting, however, they create a new set of risks that need to be considered when implementing their use.
Table 3: Average rapid upper limb assessment score of harvesting activity. Scores of 5 or greater (red colour) indicate a posture with potential posture safety issues.
Take home messages
Traditional harvesting of apples using ladders and picking bags is arguably an incredibly inefficient process with some major occupational safety risks. Moving ladders and walking to and from the apple bin consumes 24 per cent of the pickers’ time and two thirds of their harvesting time is consumed reaching into the canopy and placing the picked apple into their picking bag. Over half of the harvesting activities have the potential to lead to posture injuries.
Fruiting walls have potential to dramatically improve harvest efficiency due to easier fruit identification and access. This growing system will also be easier for robotic harvesters to handle when they become available.
Picking platforms, if properly configured have potential to eliminate most of the occupational safety risks while improving harvest efficiency, reducing the number of pickers required per unit area. An ideal picking platform will have multiple height stages and a method of transporting fruit from the picker to the bulk bin with a variable position fruit input located as close as possible to the picking area of the canopy. A full risk assessment is needed to ensure new risks with using a platform are appropriately managed.
About the reviewer:
Dr Gordon Brown
Scientific Horticulture
T: 03 6239 6411
Further reading:
Ergonomic and efficiency analysis of conventional apple harvest process.
[1] Ergonomic and efficiency analysis of conventional apple harvest process by Zhao Zhang, Yuanjie Wang , Zhaohua Zhang , Dapeng Li , Zhengze Wu , Rui Bai and Guangfu Meng.
