Mechanical pod strippers are the predominant method of harvesting lima beans (Phaseolus lunatus L.) for processing. Field losses are high, averaging 20% of potential yield in over 90 tests conducted in commercial fields. The three most significant factors that affect lima bean recovery are the field levelness, the relationship between ground speed and picking reel speed, and the lima bean variety. Further study on the relationship between pod location of four lima bean cultivars and the recovery of lima beans harvested with pod stripper combines was conducted in commercial fields. Pod location was categorized into three distinct zones of the plant. These three zones represented pods falling below the point the mainstem comes out of the ground, the first 5 cm from that point up the main stem, and all other pods higher than 5 cm above the stem. Differences in four cultivar's habits of setting pods in the three zones were established. `M-15' placed more pods in the lower zones than other cultivars. `M-15' also exhibited consistently more harvest loss than other cultivars when harvested with pod stripper combines. Other cultivars set pods higher in the plant and exhibited less harvest loss. With the harvest loss and pod set data, a rating procedure for the harvestability of lima beans was explored. While several potential rating systems demonstrated strong correlation with harvest loss data, a simple rating based on the percentage of pods in the canopy of the plant had the highest correlation coefficient (r = 0.96) with harvest loss. New cultivars can be evaluated for their harvestability characteristics using this rating system.
Edwin Kee and De James L. Glancey
Ed Kee, Tracy Wootten, and James Glancey
James L. Glancey and W. Edwin Kee
Production and harvesting systems for processing vegetables have been highly mechanized, however, field efficiencies are generally low, and high field losses and fruit damage continue to limit profits for several crops. By comparison, the number of fresh market crops currently machine harvested is small, and research to develop new harvesting technology for these crops is limited. Current mechanization research includes improvements to existing production systems, development of harvesters for crops currently hand-harvested, and the integration of new technologies into current (and future) production systems. Mechanical harvester-based production systems are evolving that reduce field losses and fruit damage, improve recovery, and decrease the foreign materials in the harvested product. However, improved cultural production systems and crop varieties that are adapted for once-over machine harvest are needed. An integrated approach in which crop characteristics along with planting, cultivating, and harvesting techniques are considered will be necessary to develop profitable and highly efficient alternatives to hand-harvest production. The integration of new technologies including differential global positioning systems (DGPS), automatic machine guidance, and computer-based vision systems offers significant performance benefits, and is a substantial component of current vegetable production and harvesting research in the U.S. In time, as the costs of these technologies decline, commercial adoption of these new methods is expected to increase.
James L. Glancey, Edwin Kee, and Tracy Wootten
The vegetable industry is important to our nation as a provider of nutritious and safe food directly consumed by our citizens. It is also critical to a rich and vigorous national agriculture. During the 20th century, engineering innovations coupled with advances in genetics, crop science, and plant protection have allowed the vegetable industry in the U.S. to plant and harvest significantly more land with higher yields while using less labor. Currently, fresh and processed vegetables generate 16% of all U.S. crop income, but from only 2% of the harvested cropland. Yet, many of the challenges in production that existed a century ago still exist for many crops. Perhaps the most significant challenge confronting the industry is labor, often accounting for 50% of all production costs. A case study of the mechanized production system developed for processed tomatoes (Lycopersicon esculentum) confirms that systematic methodology in which the machines, cultural practices, and cultivars are designed together must be adopted to improve the efficiency of current mechanized systems as well as provide profitable alternatives for crops currently hand-harvested. Only with this approach will horticultural crop production remain competitive and economically viable in the U.S.
Ed Kee, Tracy Wootten, James Adkins, and James Glancey
Proper variety selection and production practices are critical to obtaining profitable yields of mechanically harvested pickling cucumbers (Cucumis sativus L.). On the Delmarva peninsula, the tractor-mounted harvester, which utilizes the pinch-roller system for separating the pickles from the vine, was used exclusively for harvest until 1998. The pull-type forced-balance shaker machines have been introduced as an alternative harvest system. Replicated commercial-size variety trials have been conducted for four consecutive years. The trials are planted twice during the growing season, reflecting the climactic differences associated with early-season and late-season plantings. `Vlaspic' and `Lafayette' are standard varieties. Promising new varieties include `EX 1914' and `SQRP 1882'. Investigations to determine optimum plant populations and row spacing have determined that three-row beds with 60,000 plants per acre provide the highest yields and best quality fruit. Optimal operating speeds and picking reel speeds of 1.4 mph and 45 rpm, respectively, have been determined for the tractor-mounted machine. Additional design improvements have been implemented and evaluated to reduce damage. Fifty-nine replicated commercial tests evaluating the tractor-mounted harvester and the forced-balance shaker type indicate much greater harvest and throughput efficiencies are associated with the forced-balance shaker harvester, resulting in improvements between $65 and $100 per acre.
Ed Kee, James L. Glancey, and Tracy L. Wootten
Andrew M. Birmingham, Eric A. Buzby, Donte L. Davis, Eric R. Benson, James L. Glancey, Wallace G. Pill, Thomas A. Evans, Robert P. Mulrooney, and Michael W. Olszewski
A mechanical planter was developed to sow seed of baby lima beans (Phaseolus lunatus) in small plots. The mechanical seeder allowed small plots to be quickly and consistently seeded at a fixed spacing. Seeds were manually spread along a 10-ft (3.0 m) base plate containing 50 holes of slightly larger diameter than the seed length and at the desired seed spacing [2.4 inches (6 cm)]. Once all the holes were filled, a slider plate below the base plate containing holes of the same diameter and spacing, but which were slightly offset, was slid horizontally so that the holes of the base and slider plates aligned and the seeds dropped to the bottom of the furrow. Compared to manual planting, the mechanical planter increased the precision of seed placement and reduced the time needed to plant 50 seeds. The planter was easy to use and transport, and was inexpensive.