Farming with Less Fossil Fuel Won't Mean Fewer Crops
Researchers get same yields with fewer fertilizers, pesticides
Fossil energy use was compared among different crop rotation systems in a field experiment conducted between 2003 and 2008 in Boone Co., Iowa
As rising petroleum prices continue to increase the costs of producing food, new research suggests farmers can use less fossil fuel without reducing their crop yields or profits.
Modern commercial farming consumes a lot of fossil fuel. Gasoline powers farm equipment. Natural gas is a key ingredient in the synthetic fertilizers that replenish the nutrients in the soil. And commonly used chemical pest-killers are petroleum-based.
These techniques have produced remarkable productivity gains and record harvests. But oil prices have been rising all decade, and experts predict they will continue to do so.
"I think many farmers recognize that what we do now derives in a large part from relatively inexpensive energy," says Iowa State University agronomy professor Matt Liebman. "And if that system changes, then we may have to re-evaluate what's the best system for our land and our climate."
The typical commercial farm in the United States alternates between growing maize one year and soybeans the next. Liebman and his colleagues have been experimenting with alternatives.
Rather than a 2-year, maize-soybean rotation, they grew a 4-year rotation that included two other commercially valuable crops: oats and alfalfa. Since these crops are grown and harvested differently than corn and soybeans, they help disrupt the lifecycle of crop weeds. That meant the reserachers could use less weed-killer.
Alfalfa also helps return nutrients to the soil, which reduced the need for fertilizer. And when they did fertilize, Liebman's group used livestock manure rather than synthetics.
Same yields, less fossil fuels
Using these techniques, Liebman says, "We were able to reduce our use of fertilizers, pesticides and fossil fuels a lot, without reducing crop production."
In a study in the Agronomy Journal, Liebman's group produced as much or more maize and soybeans as conventional fields, but used a quarter to a half as much fossil fuel. Furthermore, farmers who followed this system would earn about as much money as their conventional counterparts.
Orvin Bontrager, a veteran farming adviser with the company Servi-Tech, gave the study mixed reviews.
"I don't doubt the savings he's seeing here on the energy," he says. "My question — several questions, I guess — would be from the labor side."
Bontrager says if most farms switched to Liebman's system, there might not be enough labor available to handle the additional crops. Plus, farmers would have to buy new equipment to harvest them. And there may not be a market for such a big increase in alfalfa.
'It comes down to economics'
But, Bontrager says, that doesn't mean farmers won't change their methods.
"It comes down to economics," he says. "If the price of oil does get that high, [then] fertilizer and chemicals obviously get a lot higher. And if the prices of crops do not follow along, then obviously we will be going to something like this because it just makes economic sense to do that."
Bontrager adds that when oil prices peaked in 2008, and fertilizer prices spiked along with them, manure became a lot more attractive. He says that shows farmers are willing to make the changes — if the price is right.