"Revolutionizing flaming equipment and techniques for certified organic weed and pest control"

Synergy of Weed Science + Engineering

What is Flaming?

Modern flaming is based on 70 year old technology and is a certified organic method of weed control. Interest in the method was very limited for 30 years (1965-1995); however, the start of an organic movement in 1990s brought about a rebirth of interest in flaming (Edwards, 1964). The fuel source for the flames is propane, one of the cleanest burning hydrocarbons. It is a thermal pest control method that harnesses the intense heat of combustion to kill weeds and insects. A common misconception is that weeds are ignited during a flaming treatment; rather, the intense heat disrupts the plant cell function and ruptures cell walls, killing the plant within a few days of treatment (Ascard, 1995a). Flaming is a very versatile tool, having applications in a large number of agronomic and horticultural crops. It also has several uses outside agriculture; for example, weed control on the concrete surfaces in urban areas.

The ‘active ingredient’ in a flaming treatment is heat energy, which is non-selective by nature. Given a difference in temperature, heat energy will transport from a hot medium to a cold medium, with the rate of heat transfer depending directly on the magnitude of that temperature difference. This fact is the basis behind flaming as a method for weed control. The very high temperature combustion gases exiting a flaming torch are able to quickly transfer a lethal dose of heat to a weed. Ignition of the weed biomass is not required for an effective flaming treatment; rather, a lethal dose of heat is one that sufficiently damages the leaf microstructure of the weed. The damage leads to water loss and the weed slowly dies over 1-3 days.

Immediately after a flaming treatment, sufficient damage can be tested by using the fingerprint test. Looking at the figure below (Figure 1), sufficient damage can be verified by a visible fingerprint remaining in a plant leaf after pressing it between the thumb and forefinger. Kang (2001) found that raising the temperature of the plant to 100°C (212°F) for 0.1 second is lethal. That goal can be achieved by exposing the plant to an estimated 800-900°C (1450-1650°F) environment for a similar time period (Thomas, 1964).

Flame weeding can reliably control weeds within the crop row, making it an excellent complement to mechanical cultivation. Adding flaming to existing cultivation methods can eliminate the need for hand weeding, which can lower operating costs for the farmer. Even more important, flame weeding can, through improved control of weeds growing within the crop row, increase yields up to 25-30% compared to yields obtained through cultivation alone.

Figure 1. Fingerprint test completed on a flamed weed leaf

The crop growth stage and equipment design are the two main factors that must be optimized to obtain successful flaming treatments. Ascard (1995a) categorized the treatments into two main types: selective and non-selective. Selective flaming treatments are done after the crop has emerged, and the objective is treating the weeds while minimizing crop damage. Non-selective treatments (also known as broadcast treatments) cover a specified path and do not distinguish between weed and crop; everything in the treatment path is fully exposed to the hot gases. The correct crop growth stage and equipment design (torch configuration and/or shielding with hoods) are critical in both types of treatments. Pre-planting, pre-emergence, and early crop growth stages are the optimal times for a non-selective treatment. The crop is not exposed to high temperatures during pre-planting and pre-emergence. During early growth stages, however, the crop must either be able to recover quickly from the flaming damage (e.g. young corn, Figure 2), or be much more tolerant of the high temperatures than the surrounding weed species (e.g. young soybeans, Figure 2). In non-selective treatments, equipment design is critical for minimizing energy input while still obtaining the desired weed control level over the entire treatment area.

Figure 2. Corn (left) and soybean (right) at the early growth stage

Selective treatments are done when the crop is at a later growth stage (Figure 3). Equipment design is critical for not only minimizing energy input and obtaining a high quality treatment, but also to minimize crop damage. Hood technology plays a large role in minimizing crop damage by keeping the hot gases near the ground and away from the crop. Figure 4 illustrates how hot gases from flaming torches are directed underneath hoods and the crop is allowed to remain above the high temperature region.

Figure 3. Corn (left) and soybean (right) at a later growth stage

Figure 4. Hood and torch configuration

Crops have a longer and much more heat tolerant stalk at later crop growth stages (e.g. late season corn and soybeans, Figure 3), and any of the lower crop leaves damaged by the flaming treatment are not critical to the crop. In general, crops will drop lower leaves anyway, because the upper crop canopy shades these leaves from the sun; without sufficient sun exposure, the energy
to maintain the lower leaves exceeds the amount of energy they are capturing through photosynthesis.

Lastly, selective and non-selective treatments can be applied in two ways: banded flaming and full flaming. Defined by the amount of area that is covered during the treatment, banded flaming applies heat to a small band (8-12 inches) that is centered on the crop row; whereas, full flaming treats all of the area within a treatment path (e.g. a full 30 in. wide crop row) .

Products

AFI has developed a series of tractor mounted flame weeding units. The revolutionary row crop flamer provides organic farmers a much needed tool to control weeds within crop rows and provides a feasible weed control method during wet conditions. Tremendous versatility is a part of its design. It can either complement existing mechanical weed control methods (e.g. rotary hoeing and cultivation), or work independently . Looking at crop applications, the current focus is corn and soybeans. However, successful preliminary testing has been completed in sunflower and sorghum (silage), and given simple modifications (i.e. hood width), the AFI flamer could be used in many other crops (e.g. alfalfa [hay], cotton, dry edible beans). Compared with existing flaming equipment, AFI’s flame weeding equipment has two key innovations, hood/torch technology and an electronic ignition system, that will yield four major improvements for the customer.

- Increased energy efficiency is realized. Existing flaming equipment utilizes open torch technology; control of the hot combustion gases ceases once they exit the torch. The hood technology complements the flaming torch, reducing heat losses from the combustion gases and providing longer exposure times at higher temperatures than open torches. With the increase in energy efficiency, the same level of weed control can be obtained with less fuel (i.e. lower treatment cost/acre)

- A higher quality, more consistent weed control is achieved. Ascard (1995a) addressed inconsistent weed control as another limitation of flaming with open torch equipment, and wind is the major reason behind the inconsistent weed control when open torches are used. Wind can wreak havoc on the effectiveness of existing flaming equipment. It can evacuate the heat out of the treatment zone earlier than normal, resulting in little damage to the weeds and a failed treatment. Wind is an element of the weather that is frequently encountered in the field, and in order to hit the right treatment timing, moderate winds have to be tolerated. Utilizing a hood eliminates the issues caused by wind.

- Flaming treatments are safer with hoods. The importance of safety cannot be stressed enough when dealing with the high temperatures of combustion. Open torches can be dangerous and wind is to blame in this case as well. Nothing stops the wind from carrying the hot gases out of the treatment zone and into possibly dangerous locations where equipment could be damaged or an operator could be burned. Flaming hoods aid tremendously in keeping the hot gases contained and away from the equipment, the operator, and the crop.

- The AFI flamer is easier to operate. An electronic ignition and detection system makes operating the equipment much easier and safer. No longer does the farmer need to continue the dangerous practices of manually lighting all of the torches or turning around in the end-rows of the field with the system in pilot flame mode. AFI’s ignition system automatically ignites and extinguishes the torches. It will also monitor the torches through flame detection, and reignite a torch if it extinguishes during a treatment. If a torch cannot be reignited, the ignition controls will simultaneously shut the system down and warn the farmer of the problem torch.

Following AFI’s plan, the farmer will be provided with recipes for treatment of various crops and will know what to expect after flaming treatment is applied. Looking at what is to be expected from a treatment, the major question deals with the effect of flaming on crop yield. Field testing has verified successful weed control in the following agronomic crops: corn, soybeans, sorghum, and sunflower.

Our flamers control weeds within the crop row, which are impossible to remove by cultivator, directly protecting crop yield and resulting in up to $450 per acre in additional revenues. We have observed this at many experimental fields of the University of Nebraska, and at many organic farms that have been using AFI flamers over the last few years. This extra income from increased yield by flame weeding was also confirmed independently by many organic farmers that regularly attend Midwest Organic and Sustainable Education Service (MOSES) conferences held annually in La Crosse, WI.

Flame Weeder Models Available

1. Safety:

the equipment is designed with SAFETY as the highest priority

2. Electronic Ignition:

since the flames are often not visible in daylight, each torch is monitored and the operator on the tractor is alerted if there is a torch failure

3. Flame Detection:

since the flames are often not visible in daylight, each torch is monitored and the operator on the tractor is alerted if there is a torch failure

4. Robust Torches:

combustion stability (very rarely flame out), efficiency, ease of adjustment for Banded or Full flaming are features built into every AFI torch

5. Convenience & Flexibility:

Category 2-3 Three-Point Hitch, Storage Stands integrated into each machine, and Adjustable Gauge Wheels

6. Specially-Designed Hoods:

heat is held close to the ground, providing more consistent treatment results, especially in windy conditions

7. Propane Dose Tables:

provide the pressure settings and tractor speeds required to apply a full range of propane doses for effective flame weeding

8. Flame Weeding Manual:

includes propane dose and timing recipes for effective flame weeding of all major row crops

About US

George Gogos

CEO and Lead Product Developer

Academic Degrees:

Ph.D., 1986 University of Pennsylvania

M.S., 1982 University of Pennsylvania

B.S., 1980 Massachusetts Institute of Technology

30 plus years of research in heat transfer, fluid mechanics, and combustion science, including:

-Flow & heat transfer using functionalized metallic surfaces

-Vaporizing and combusting sprays

-Flame weeding equipment design and development

Chris Bruening

Lead Product Developer / Design Engineer

Academic Degrees:

Ph.D., 2017 University of Nebraska–Lincoln

M.S., 2009 University of Nebraska–Lincoln

B.S., 2006 University of Nebraska–Lincoln

A combined 10 plus years of research in flame weeding and flame weeding equipment design and development

Vision:

Revolutionize flame weeding equipment and techniques for weed and pest control.

Mission:

Provide safe and efficient flaming equipment that yields higher quality treatments.

Synergy of Weed Science and Engineering

Agricultural Flaming Innovations (AFI) is an equipment research, development, and manufacturing company that is helping to solve the biggest problem for farmers: weeds. The collaboration between engineers and weed scientists allows the AFI team to offer farmers a highly innovative product with key innovations that U.S. competitors have failed to bring to the market. AFI’s equipment provides weed control in corn, soybean, sunflower and sorghum.

AFI has addressed the issues with flaming through the key innovations of hood technology (patent pending), efficient vaporizer/torch unit (patent pending), an ignition and flame detection system (patent pending), and treatment recipes for individual crops (patent pending). These innovations offer farmers four major improvements in flaming equipment: increased energy efficiency, higher quality weed control, especially in windy conditions, and increased safety and ease of use. In collaboration with the University of Nebraska, AFI has also made significant contributions to flaming treatment knowledge. Testing has shown that the AFI flamer can eliminate the need for hand weeding, offering organic producers huge cost savings. The flaming treatments cost from $5-20/acre, and even more important, it can effectively treat weeds that grow within the crop row, which are typically more difficult to control through cultivation. As a result, using AFI flame weeders can increase crop revenue by as much as $450 per acre through increased yields (compared to revenues and yields obtained through cultivation alone).