Agriculture Reference
In-Depth Information
7.3 MECHANICAL MASS HARVESTING OF
FRUITS, NUTS, AND VEGETABLES
Harvesting costs represent 30-60% of total production cost and is one of the most
labor-intensive agricultural operations (O'Brien et al., 1983). In countries where man-
ual farm labor is scarce and expensive, mechanical harvesting is the primary solu-
tion for processed fruits and vegetables. Although recent advancement in technology
has made the adoption of mechanical harvesting easier, there are two constraints
that need to be considered before using mechanical harvesting. The first constraint
is the horticultural characteristics of the plant and the crop to be harvested. These
characteristics, which can affect harvestability, may include plant size, planting den-
sity, fruiting pattern and density, and annual versus perennial crops. For example,
when Valencia oranges are harvested in mid-March, immature fruits for the next
season have already bloomed and the fruit has set, which presents a challenge to
mechanical harvesting because the next-season crop could be negatively affected by
excessive canopy or trunk shaking. Other concerns may be excessive fruit damage
or bruising, contamination, harvest and catching efficiency, harvesting throughput,
fresh versus processed market, and labor productivity measures. Negative effects of
mechanical harvesting on the product must be clearly established before continu-
ing with mechanical harvesting. The second constraint is the economic aspect of
mechanical harvesting, which can be influenced by system costs, labor costs, har-
vesting efficiency, fruit loss, maintenance costs, and so on. Ultimately, the econom-
ics and intrinsic value of mechanical harvesting must favorably exceed labor costs
and availability-related issues associated with manual labor, since the grower's main
interest is maximizing return of investment and ensuring that his crop is harvested.
7.3.1 C
LASSIFICATION
OF
M
ECHANICAL
H
ARVESTERS
During manual harvesting, humans generally perform four basic functions: selec-
tion, control, removal, and transportation. First, the mature fruits are selected. Then
the hand is guided toward the fruit, which is the control function. The picker then
detaches the fruit from the tree in a manner that does not cause injury to either the
fruit or tree. The detached fruits are placed in a container to be transported to the
processing plant or fresh market packer. Placing the fruits in the container is another
form of control function. The picker then moves to another location where fruits
have not yet been harvested. Lastly, the harvested fruits are transported to roadside
where they are loaded on trucks, which will transport the fruit to either a process-
ing plant or fresh market packer. These four basic functions will be incorporated
into automated harvesting to obtain the same overall outcome, but hopefully with
significantly improved labor productivity, reduced production costs, and thus a better
return on investment. Automated harvesting can be implemented using either a mass
harvesting approach or a selective harvesting approach. In general, mechanical mass
harvesters are used for processed fruits, whereas robotic selective harvesters would
be used for fresh markets. Each has its own advantages and disadvantages.
Because there are many varieties of fruits, nuts, and vegetables, general clas-
sification of mechanical harvesters is difficult. Srivastava et al. (2006) suggested a
