Performance and Economic Analysis of a Selective Asparagus Harvester

Developing and adopting harvesting systems for asparagus provides an important means to address increasingly urgent industry concerns including the rising cost of labor and global competition. These mechanical systems will help to maintain U.S. and particularly, the state of Washington's position in national and international markets. Minimum wage will increase to over $7.93/h in 2007 in the state of Washington, and changes in international trade policies have presented significant challenges to the asparagus industry in the state of Washington. The asparagus industry has been impacted by imports from Peru. In addition to foreign competition, labor for hand harvesting asparagus has become scarce, particularly at the end of the season. It is common for fields to be abandoned prematurely due to lack of labor. This has prompted the industry to evaluate mechanical harvesting in order to reduce production costs associated with hand labor and extend the harvest window when hand labor is not available. In the spring of 2006, four selective mechanical asparagus harvesters were evaluated (Oraka, New Zealand; Larsen, Wash.; HiTek, Ala.; Geiger Lund, Calif.). The most successful harvester was a single row asparagus harvester prototype developed by Geiger Lund Harvesters (Stockton, Calif.). The harvester head employs parallel pairs of counter-rotating "rollers" that engage asparagus spears that have reached a specified height. As the machine moves down the row, the optical system senses a spear of the selected minimum height and actuates a cutting system that drives the closest blade into the soil at the base of the spear. The spear is pulled through counter-rotating rollers onto a backstop and conveyer that transports spears to the rear of the harvester. Economic analysis indicates that a four-row harvester must recover 70% of hand-harvested yield to be break even. It was concluded that with further improvements to the harvester, it would be successful at achieving an efficiency of 70 to 80% compared to hand harvesting. Damage to the spears was not significant.