School of Economic Sciences

Agribusiness Management

Simulation of Harvesting Asparagus: Mechanical vs. Manual

by Tiziano Cembali, Raymond Fowlell and Trent Ball

The primary purpose of this study was to develop a bioeconomic simulation model to examine the issue of harvesting asparagus, with the objective to determine the impact of different management strategies in the harvest. The dissertation is separated in three articles. In the first article the model was successfully validated using data from different locations for four consecutive years in Washington. The impact of the minimum wage requirements was evaluated in terms of yield and profit for both processed and fresh asparagus. The traditional harvest interval of 24-hour was compared to a more frequent interval (12-hour) and a less frequent intervals (48-hour). Manual harvest with the interval of 12-hour showed to be the best results in terms of yields and profits for both processed and fresh asparagus.

In the second article, break-even recovery rates were calculated. The average break-even recovery rate for the period 1989-2004 was 70.15 percent for the 24 hours harvesting interval in order for the mechanical harvester to be economically acceptable in place of hand harvesting. The 28, 32, and 36-hour harvesting intervals produced break-even recovery rates that were not statistically different from the 24 hours interval. By increasing the manual harvesting costs from US$0.51/kg to US$0.60/kg the recovery rate needed by the mechanical harvester to break-even with manual harvesting decreased from 70.15 percent to 61.30 percent.

In the third article, the CHO accumulation was included in the bioeconomic simulation model of asparagus to examine the inter-year effect of harvesting. The results using the actual level of CHO used showed yields and production consistent with actual results. By increasing the CHO level for stopping the harvest to 210 g/plant, an increase in terms of net present value, profit, and yield is recorded. Results with price trends with favorable prices at the end of the season confirmed that the CHO level of 210 g/plant is the one that can provide the highest performances in terms of net present value, yields, and profits.

© 2004 by Cembali, Folwell, and Ball. All rights reserved. Readers may make verbatim copies for noncommercial purposes by any means, provided that this copyright notice appears on all such copies.

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Selected paper prepared for presentation at the Western Agricultural Economics Association annual meeting, Honolulu, Hawaii, June 30 -
July 2, 2004


Asparagus harvesting methods and strategies have remained unchanged since inception in Washington. A bioeconomic model was developed to determine the profit optimizing frequency of harvesting for manual and mechanical harvesting techniques. The mechanical harvester is economically viable if the harvester cuts 72.3 percent and 73.55 percent of what a hand crew would cut for process and fresh utilization, respectively. The results indicate that decreasing the frequency of harvest increases profit for asparagus used in processing. This research is the first attempt to address the problem of asparagus harvesting with a bioeconomic model.


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