New Mexico State University research: Mechanical chile thinner nears market

New Mexico State University is developing a mechanical prototype of a thinning device for chile that could be commercially available for pod producers by next spring.

During the spring, New Mexico chile growers typically plant more seedlings than they need to withstand unforeseen wind, salt, insect or disease damage. As a result, plants are often too crowed by mid-season for available water, light and soil conditions.

At that point, many producers hire thinning crews, if they can be found, to reduce plant numbers.

“This can happen once and sometimes twice a year at $150 an acre, which is a significant cost,” said Rich Phillips, a project manager with NMSU's Cooperative Extension Service and a project coordinator with the Chile Task Force.

The ongoing hand-labor expense motivated the task force and it's prototype developer, NMSU's University's Manufacturing Technology and Engineering Center (M-TEC), to produce a mechanical chile thinner to provide uniform, flexible and timely treatments, he said. Another advantage is the ability to put off thinning until late in the season in order to gauge the effects of disease damage.

Green chile and its ripened version, red chile, are among New Mexico's most popular cash crops. In 2001, more than 17,000 acres produced 81,000 tons of chile, mostly in the four-month span between July and October.

Once picked and processed, chile is the state's most valuable vegetable, raking in more than $200 million annually.

Developing a new chile thinner was no easy task, since there's little in the way of modern examples.

“Chile is really a niche market, and there simply aren't a lot of major equipment manufacturers out there making machinery for this particular industry,” said Wes Eaton, M-TEC's lead design engineer on the thinner project.

However, the researchers did have one reference point: a 40-year-old John Deere sugar beet thinner, which Vince Hernandez, production coordinator for Biad Chili in Las Cruces, suggested that engineers study. Hernandez found the sugar beet thinner on a farm near Portales.

Tests using the aging machine revealed some useful pointers for the new device.

One lesson learned was elimination of time-consuming manual adjustments, which can slow fieldwork to a crawl. In the NMSU prototype, a chile farmer has only to punch in the desired blade spacing, cutting depth and sensor height on a computer screen.

The machine automatically makes the required adjustments.

The NMSU prototype thinner uses an electronic sensor ahead of a cutting blade to mark the chile plants' location in a programmable logic controller, said Ryan Herbon, a M-TEC engineer.

As the machine rolls forward, plant location data is forwarded to the thinner's cutting mechanism, which can be adjusted to slice two to 12 inches out of the chile row, depending on the desired spacing. The cutting blade swings back and forth across the row much like a pendulum, cutting to a depth of about one inch.

“The machine's software knows exactly where each plant is, and how far the machine has traveled, to one-tenth of an inch,” Herbon said. “The machine only cuts when a plant is sensed, ensuring any natural spacing is not increased.”

The modular setup of the prototype allows it to thin two to eight rows to be used because each row unit operates independently on a single tool bar. A tractor pulls the entire unit through the field.

The thinner can be used throughout the early growing season on plants ranging from tiny seedlings up to plants 16 inches tall.

“We anticipate that a commercial model of this chile thinner will be available next spring,” Phillips said. “It's that important to us.”

A new chile thinner is also critical to the expansion of a labor-saving mechanical chile harvesting because thinning creates uniform stand density needed for efficient, effective harvest, he said.

During the next few months, the prototype thinner will undergo a series of field tests, starting at NMSU's Leyendecker Plant Science Center near Las Cruces.

“Our ultimate goal is to have this machine on the market and available for New Mexico farmers,” said Anthony Hyde, M-TEC director. M-TEC, housed in NMSU's College of Engineering, is an outreach program chartered to provide engineering assistance to businesses in New Mexico to aid in economic development.