Weeds Got You Burned … Flame Cultivation Is the Solution

Propane Provides Effective Weed Control for Organic Soybeans


Washington, D.C. (July 30, 2004)—Agricultural producers could soon be realizing that propane is the exceptional energy solution they have been searching for to control weeds in organic and non-organic crops.

A recent propane industry-funded study revealed that flame cultivation with propane significantly reduces weed competition compared with conventional cultivation systems and considerably lowers labor costs associated with hand weeding. With flame cultivation, weeds are exposed to enough heat to vaporize the water within the cells, destroying the plant’s photosynthetic capabilities. The application cannot be reversed or compromised due to an immediate rainfall, as is the case with some chemical treatments.

“For many years, effective herbicides have been the most popular option for weed control on the farm,” said Propane Education & Research Council (PERC) Agriculture Programs Manager Mark Leitman. “But now, environmental and weed-resistance issues have many producers looking for alternatives. Flame cultivation with propane can offer agricultural producers a clean-burning and environmentally safe weed control option. It also minimizes tillage, reduces soil erosion, and preserves soil moisture.”

According to Mississippi State University Extension Weed Scientist Dan Poston, who conducted the PERC-funded research, fields treated with flame cultivation had 75 percent to 93 percent weed control in early-planted soybeans, enabling the organic soybeans to achieve yields up to 65 bushels per acre. In his study, Poston used a parallel-row, covered flame burner developed by researchers at Texas A&M University to treat weeds in soybean fields. Parallel-row, covered flame burners have also been tested for controlling weeds in cotton, and the technology may be applicable for other row crops, including organic.

More fuel efficient and effective than open-flame burners, covered burners extend the exposure time of the weed to the flame temperature and heated air by restricting the heat from rising. The design of the parallel-row, covered burner also allows flame cultivation to occur at early stages of crop growth when weeds are easier to kill.

Planting time and application speed can also impact revenue. When using flame cultivation, early-planted soybeans yielded 11 more bushels per acre than late-planted soybeans. The amount of propane consumed and cost for each flame cultivation treatment varied based on the speed of the tractor pulling the burner attachment. At 4 miles an hour, 6.12 gallons of propane would be used for a cost of $5.20 per acre, compared with $7.06 an acre for 8.3 gallons at 3 miles per hour. The cost was based on a summer rate of 85 cents per gallon of propane. According to the study, three to four flame cultivation treatments per season would be needed to effectively control weeds in organic soybean fields with propane. 

Additionally, Poston’s research revealed farmers could achieve higher net returns using flame cultivation to control weeds in organic soybeans than they could with other soybean production systems, including biotechnology, because the price of a bushel of organic soybeans is typically twice the price of non-organic soybeans.

“This research demonstrates how flame cultivation can play a significant role in making propane a cost-competitive alternative for weed control, particularly in organic crops,” Leitman said. “As a result, the propane industry believes this is an opportunity to increase propane usage as organic crop production continues to expand.”

A 2002 International Trade Center study projected organic sales could grow between 10 percent and 20 percent over the next 10 years. U.S. farmers have responded to the growing demand and the added value of organic products by producing approximately 2.3 million acres of organic crops and pasture. A report from the U.S. Department of Agriculture forecast organic soybean production alone will reach 500,000 acres in 2004.

Flame cultivation is an example of thermal agriculture, which is an area of interest that the propane industry is focusing on to develop new technologies and increase propane utilization. Other examples of thermal agriculture being researched by PERC include steam cultivation, poultry house sanitation, and crop defoliation.

“The propane industry, through PERC, is funding innovative thermal agriculture research and has made a commitment to educating agriculture producers and the rest of the agriculture industry on these technologies, as well as on the benefits of propane as an energy source,” said Leitman.

Propane’s portability, high-energy output per gallon, and clean-burning properties are among the qualities cited for its effectiveness in weed control. It does not require much equipment or the special handling procedures that come with chemical herbicides. Propane is insoluble and nontoxic, so it’s not harmful to soil or water.

PERC’s vision in agriculture is that by 2010, the agricultural industry will recognize propane as a preferred energy source offering exceptional value. This value is achieved through a unique combination of product benefits, including cost-effectiveness, efficiency and productivity, reliability, portability, and environmental friendliness.

For more information on PERC and its programs to promote the safe and efficient use of propane in agriculture, call (202) 452-8975 or visit www.usepropane.com and click on the “Trades” link.