EDMONTON, Alberta – A company’s claim of replacing farm fertilizer with tractor exhaust is being disputed by a reputable agricultural scientist.
Doon Pauly, a crop specialist with Alberta Agriculture, Food and Rural Development in Stettler, said tractor exhaust fertilizer is, at best, a good theory.
The exhaust is made up largely of carbon dioxide and nitrous oxide gases. When it is injected into the soil in the same manner as anhydrous ammonia, according to Pauly, it escapes into the atmosphere since there is nothing to bind it to the soil.
“The first major problem is that the soil is a porous material,” Pauly said. “There is no evidence to suggest that tractor exhaust is retained by the soil. Nor is there any reason why it should be retained.”
Gary Lewis, Pincher Creek, Alberta, and Darrel Carlisle, Souris, Man., have been touting a mechanism made of a series of stainless steel pipes that capture a tractor’s exhaust, cool it, run it through the air seeder to circulate seeds and finally inject it into the soil as a fertilizer.
Lewis spoke to the Manitoba-North Dakota Zero Tillage Farmers Association conference in 2007 and was back again at the Minot conference in 2008. He holds two Canadian patents on the exhaust injection system.
Lewis told The Minot Daily News that Pauly has a lot of misinformation about the company, called Bioagtive, as well as the exhaust mechanism.
“Anybody who thinks that exhaust is the same as atmospheric air does not understand the chemistry of volatilized organic matter,” Lewis said. “The great news is that biofuels are perceived to be lower in emissions, but they create more favorable emissions to the soil.”
Carlisle also attended the 2008 Manitoba-North Dakota Zero Tillage Farmers Association conference.
He said 50 Canadian farmers used the system in 2007 on approximately 200,000 acres. He expects 85 farmers, including at least one in Montana, will be using the equipment this growing season. Craig Henke, Chester, Mont., and Ken Yirsa, Big Sandy, Mont., are currently listed on the Bioagtive Web site as U.S. distributors.
Each system costs approximately $40,000 to become operational.
The system collects exhaust emitted from the tractor and uses it instead of outside air to move seed and fertilizer inside the air seeder.
“We take the exhaust off the turbo, pipe it in back through a cooling chamber and then pump it into an air seeding fan,” Carlisle said.
According to Lewis, the exhaust should not be compared to traditional fertilizers such as anhydrous ammonia or urea. Instead, he said it’s a catalyst for nature to trigger biological influence of plant growth.
Lewis said there is a common belief in agricultural agronomy that tons of inorganic salts applied to the soil are needed to grow a crop, disregarding the actual fertility of the soil.
“The Bioagtive method stimulates the biological life within the soil so the new seeding and photosynthesizing carbon dioxide from the atmosphere is done at a greater rate,” Lewis said. “The enhanced carbon flow to our soils from the emissions of the tractor starting the biological influence, is a small influence to a large reaction powered by the sun.”
According to (Bioagtive.com), a Web site maintained by Lewis, soil naturally has organic nitrogen that plants can’t normally access, unless soil bacteria is converted to inorganic nitrogen forms.
And that is where the tractor exhaust comes in. Because the exhaust is mostly carbon dioxide, it is quickly converted to carbon when it is injected into the soil.
Soil bacteria feed on the carbon, converting it to an inorganic form. As it enters the soil solution, it is taken up by plants, reducing the amount of fertilizer that would normally be applied and utilized.
Carlisle said he has cut fertilizer rates by 75 percent without any decrease in yields. The system replaces the equivalent of 8 pounds of carbon dioxide per acre, reduces tractor emissions by 95 percent and doesn’t appear to add any toxins to the soil.
But that is where Pauly has an issue with Lewis’ invention. He said there is no evidence anything in exhaust would be beneficial or detrimental for soil organisms or plants.
“They seem to truly believe in their product,” Pauly said. “I maintain that any farm that adopts this ‘technology’ and uses it for any length of time will mine their soil of nutrients and will suffer substantial economic losses.”
Lewis didn’t offer long-term statistics, however, said he has had numerous conversations with Pauly about the Bioagtive system. He suggested the proof of success is in the producers who are operating the system.
Pauly is convinced enough the system doesn’t work that he’s posted a list of cautions for producers on the Alberta Agriculture, Food and Rural Development Web site, which is operated by the provincial government.
The cautions include:
No. 1: Ensure the products are registered for use. Tractor exhaust as a fertilizer replacement is not a product that must be purchased as it is already on farm and is produced whenever diesel engines are operated.
What is sold by the proponents of this process is an emissions system that transfers exhaust from the engine through a serpentine arrangement of tubing to the intake side of the fan on air seeding equipment. The need to register a fertilizer product probably doesn’t apply if there is no product sold.
No. 2: Examine product claims critically: Tractor exhaust is supposed to stimulate soil organisms and consequently plant growth. Theoretically this benefit is from carbon dioxide and nitrous oxide, which can be grouped together in exhausts and blown into the soil.
There are several problems with this theory. The first problem is that carbon dioxide and nitrous oxide are gases, but there is no mechanism in the soil to retain these gases in well aerated conditions. Any added gases would also be lost from the soil.
The second problem is that although nitrous oxide contains nitrogen, it is not a plant nutrient. Nitrate is the most common form of plant-available nitrogen in soil and soil organisms can convert nitrate to nitrous oxide, but there is no soil processes that oxidize nitrous oxide to nitrate.
The third problem with exhaust as fertilizer is that the quantity of gases added to soil is insignificant. It is estimated that half a gallon of diesel fuel burned working an acre of land adds about 10 pounds of carbon dioxide to that acre.
However, carbon dioxide given off by soil from microorganisms and root respiration ranges from 65 to 90 pounds per acre per day.
Over a typical 100-day growing season, the normal carbon dioxide evolution from soil is 400 to 800 times greater than the carbon dioxide in exhaust added in a single field operation.
No. 3: Value products based on fair value of nutrient composition: There does not appear to be any evidence that tractor exhaust provides any appreciable level of plant nutrients.
Consequently the value of exhaust is essentially equal to the value of air blown into the ground by an air seeding system that doesn’t have the added tractor exhaust emissions.
“I would encourage you to research this for yourself and compare the information from Bioagtive with a basic soil textbook,” Pauly said. “High fertilizer prices should make producers question their current practices and seek ways to improve cropping efficiencies. However, before purchasing any unproven product, be sure to apply these three principles. If questions still remain, seek out the services of a respected agronomist.”
