University of Nebraska-Lincoln College of EngineeringOnline: Spring 2012
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  A Field of Opportunity headline and photo  


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A University of Nebraska-Lincoln collaboration has brought forth weeding solutions that organic farmers are testing with excitement throughout the Midwest.

Gogos photo Flame weeding is not a new idea, but it has received a modern boost from UNL mechanical engineers and agricultural scientists. Agricultural Flaming Innovations is the company formed by George Gogos, professor of Mechanical & Materials Engineering; Steve Knezevic, professor of agronomy; and Chris Bruening, an MME graduate student. Lanny Nissen '69 MECH, with 42 years of experience including 36 years with Kawasaki, recently joined AFI as a co-owner.

Knowing plants’ adaptability to herbicides and the environmental concerns with both herbicides and tillage, Knezevic had studied propane flaming, a thermal weed control method. In 2007, he connected with Gogos, who applied his years of combustion expertise to the concept. Gogos and Knezevic envisioned a multi-torch farm implement that could treat four to six crop rows at a time. They began research at UNL’s Haskell Agricultural Lab in Concord, Neb.

Knezevic photoKnezevic knew several Nebraska crops—including corn, sorghum, soybeans and sunflowers—were great candidates for thermal weed control. Heat from an early season flaming treatment, when the crops’ growing points are still beneath the soil’s surface, would not be lethal to those plants. Amid the crop rows, however, harmful broadleaf weeds like redroot pigweed, waterhemp, morning glory, velvetleaf, lambsquarter, kochia and ragweed—with growing points above ground and fully exposed to the heat—would be killed by flaming.

The term “flaming” is a misnomer, according to Gogos. “There is no burning of the weeds,” he said. “Leaf exposure to the hot gases destroys the cell membranes, which initiates water leakage. The weeds wilt shortly after treatment and slowly die over the next few days.”

Bruening photoBruening became involved when he was asked to retrieve some of the flame weeding research data from the Concord lab, near the farm in Saint Helena where he grew up. That routine errand ultimately changed Bruening’s academic career and now, as a Ph.D. student, he is part of a start-up company and earned the prestigious Peter Kiewit Student Entrepreneurial Award in 2010 for his work in field studies and data gathering to improve flame weeding technology.

From farming in northeast Nebraska, Bruening was aware of “a growing concern in the United States—especially in top crop-producing states like Iowa, Illinois and Nebraska—with the degradation of water quality due to pesticide runoff from fields.”

For organic farmers, even the age-old practice of tillage for weed control has its downside: turning the soil reduces the moisture available to crops and increases the chance for erosion. The AFI team found that propane’s availability and its relatively safe and clean-burning nature make flame weeding viable for organic and even some conventional farmers.

For the mechanical engineers, the first challenge was designing the device’s hood configuration. They started with single flaming units in the College of Engineering’s machine shop and then scaled up the design with four-row iterations produced by Lincoln manufacturers Source One and Total Manufacturing Co., Inc. (TMCO).

At that time, Gogos presented the work to members of the Engineering Dean’s External Advisory Board, and gained several alumni mentors—including Ken Jones ’68 CHME, Kevin Schneider ’85 MECH and Jeff Zvolanek ’86 MECH. Project funding has been provided by the Propane Education and Research Council (PERC), the U.S. Department of Agriculture, as well as through the Nebraska Engineering Research Fund via donations to the NU Foundation.


AFI’s initial four-row implement was pulled by a typical farm tractor with a three-point hitch. It included a tank and supply network on a frame, with eight torches directed under a low-lying hood assembly, and configuration adjustable to the row width and the growth stage of the crop—with best results in corn, sorghum and sunflower.

Bruening field tested the flame weeding prototype device during growing seasons with four organic farmers in Abie, an hour’s drive north of Lincoln. Knezevic used that data to study the effect on soil erosion. Further testing at the Haskell Ag Lab yielded excellent results with the four-row flaming unit: “chemically-clean” with greater than 80 percent season-long control of weeds, deemed an excellent level of weed control by organic producers.

Nissen photo Back in the lab, AFI developed its own torch vaporizers, improving on commercially available versions they’d used in their research. AFI’s design was aimed to better stabilize the flame and burn more efficiently, which Gogos said led to two patents.

“We developed an automated system with flame detection and reignition for each torch, as well as a pendant with LED panels that the farmer can use to electronically monitor the entire system of torches,” Gogos said. He estimated the price for the manufactured four-row weed-flaming unit at $15,000.

Bruening said a season might require one to three flaming treatments to the field. With the device using an average of five gallons of propane per acre, the full season cost would range from about $7 to $21 per acre, depending on the number of treatments and the price of propane. For certain chemical control methods, he estimated the cost per acre ranges from $20 to $75 for a full season.

An April 2012 USA Today article documented Mississippi Delta farmers’ weed control costs doubling, to $100 per acre in some cases, due to plants becoming resistant to glyphosate, commercialized as Roundup.

Beyond treatment cost, removal of chemical herbicide from the environment offers significant value, Gogos said, especially when the flame weeding process can preserve and enhance crop yield.

The summer of 2012 looks busy for AFI and its partners: Behlen Manufacturing (Columbus, Neb.), for marketing and sales of AFI products; Lincoln’s TMCO, the main fabricator, and MIS Engineering, handling flame detection, reignition and electronic controls; and Moore-Built (Benedict, Neb.), constructing the toolbar for AFI’s larger eight- and 12-row units.

Gogos said field testing and data gathering also continue. Eight demonstration units are strategically placed for the growing season with eight farmers in Midwest locations: Abie, Ridgeway, Iowa.; Fairchild, Wis.; Tampico, Ill.; and Braggadocio, Mo.

This fall, AFI plans to manufacture several four-, six-, eight-, 10- and 12-row units. Requests from conventional farmers add to the orders, with a David City, Neb., farmer already using a six-row unit this growing season.

by Carole Wilbeck

Athens archeology site

Another area for AFI’s flame weeding testing is more archeological than agricultural. Gogos and Knezevic are consulting with weed scientists and archeologists to use flame weeding at several sites, in a project funded by the European Union. “We are starting with the ancient Agora in Athens, from the fifth century B.C.—right underneath the Parthenon,” said Gogos, who was born and raised in Greece.


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