Automated Benching Systems

May 9, 2002 - 11:51

In the automated greenhouse benches are much more than just a place to grow plants.

Last month’s article focused on options for material
movement when growing on the floor, but what about growing on bench systems?
Creating the proper environment for crops should be the single most important
criterion when deciding on a production method, though in the past, economic or
labor considerations have been the prime decision factors. The traditional view
was that growing on the floor (without flood floors) was the least-expensive
alternative and offered the most flexibility and that growing on benches cost
more money but was more accessible.

Advances in automation technology have changed the
traditional reasoning, making this more of a personal-preference decision.
Flood floor systems and automated benching systems cost approximately the same,
and automation exists for both systems that allows efficient use of labor and
maximum flexibility.


Benching Basics

When a grower decides to grow on benches, a mobile system
should be seriously considered. These systems are available in varying degrees
of sophistication. Many articles have been written on operations in The
Netherlands where only four people are needed to operate a 4-acre range. The
bench systems in these ranges are totally automated, and people, theoretically,
never go in the growing range. I have seen one of these operations growing four
acres of Boston ferns, and it was an extremely efficient operation. However,
U.S. growers cannot make a living growing one crop with a 16-week cycle.

Systems do exist that provide the American grower with an extremely
efficient method for moving large amounts of product in a relatively short
period of time without total automation. Automated bench systems can be
designed with or without flood bottoms, allowing the benches to be both a
transport system and an integral part of the irrigation system, from plastic or
metal, with mess or solid bottoms, etc. The only real defining characteristic
of automated bench systems is that the benches are designed to ride on a system
of rails that allows them to be moved from the headhouse to the greenhouse and
on to the shipping area. In many instances, the movement to and from the
headhouse is done using a powered transport line, while the movement of the
bench to and from its position in the greenhouse is done manually. It is possible
for two people to easily move even a 20-foot bench. Because of this, any given
bench can be placed in position on the transport line, providing the
flexibility so crucial for the American grower. This manual movement is
surprisingly quick.

To be most efficient, a bench system must be designed as
part of an integrated system. The flow of the crops through both the greenhouse
and the headhouse must be considered. Optimally, newly planted crops will enter
the greenhouse on one end, and finished crops will exit the greenhouse on the
opposite end, creating a circular product flow through the facility. The
greenhouse itself must be sized to allow maximum space utilization. A properly
designed system of bench and greenhouse uses space as efficiently as a flood
floor system. The headhouse must be planned to allow for automatic washers for
the benches as well as equipment to automatically load the benches. This
supplemental equipment need not be part of the initial investment.


Benching in the Future

One of the most exciting aspects of automated benching
systems is the future potential. Technology is being tried in a greenhouse
environment that uses bar coding to identify the location of every bench and
describe the plant material on it, an invaluable aid in inventory control. This
information can also be used to guide the irrigation equipment so that
fertigation is unique to each bench.

Cynics may say that automation has made both benching and
floor-growing systems very expensive. However, this is only true when looking
at the initial installation cost. As with any automation decision, it is
critical to look at total operating costs over the life of the equipment. When
labor savings, efficiencies and standardization are considered over the life of
the product, the cost is very reasonable.

With all the technology available, and the size of the
investment required, how does a grower decide on the proper system? The keys to
this decision are no different now than 20 years ago. There never has been nor
is there likely to be a substitute for the instincts of the grower. See what
others are doing, decide what you need, consult your manufacturer and trust
your instincts.

About The Author

Mike Porter is president of Nexus Corporation, Northglenn, Colo. He can be reached by phone at (303) 457-9199 and E-mail at

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