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Selective
Harvester 2004 Trials |
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by
Trent Ball*
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A
selective mechanical asparagus harvester was tested in Washington
State’s Columbia Basin to evaluate its commercial viability
in the spring of 2004. The one row harvester uses a sensing system
that detects when a spear crosses at a pre-selected height and sends
an appropriate blade to cut the asparagus, anywhere from one inch
below ground to one inch above ground. The spears taller than roughly
6-7 inches are engaged in a pickup unit and are lifted onto a cross
conveyor if the spear is cut by the machine. Otherwise the spears
pass through the pickup unit and remain for harvest the following
day. Harvested spears are transported via conveyors to a station at
the rear of the machine where an individual sorts and aligns the asparagus.
Although the harvester has the capability to harvest three rows simultaneously,
the current evaluation procedure is focused on one cutting mechanism
until it harvests satisfactorily. |
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The machine
harvester travels at approximately 2 miles per hour. If it was a three-row
harvester it is estimated that the machine could harvest approximately
50 acres in a 16-hour period. One driver would be necessary in addition
to two manual sorters on the back of the machine. |
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The spring
trials revealed that on average the machine-harvested product had
a grade of 15% butts, 19% culls, 53% 9-inch spears, and 13% 8-inch
spears, for a number one grade of 66%. Although the grades are satisfactory,
the amount of product harvested compared to the hand crew needs improvement.
Several mechanical issues during the spring 2004 trials resulted in
dropped spears that were cut by the machine. Had all spears cut by
the harvester been collected the machine would have an estimated pay
weight of 56% compared to manual harvesting. |
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In the fall
of 2004 additional improvements were made including adding more blades
with smaller knives to reduce potential damage in the field. Further,
the sensing system and electronics were altered to increase the sensitivity
of detecting asparagus spears. These improvements in addition to other
changes should increase the efficiency of the harvester. In January
further trials are planned to test the modifications in anticipation
of redesigning the machine to run trials in Washington for the entire
harvest season in 2005. |
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*Trent
Ball is an Associate in Research, working with Dr.
Ray Folwell, on the asparagus project. He recently, Spring
2004,
traveled to the Columbia Basin, Washington to study the Selective
Machine Harvester and its affects on the asparagus industry. |
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