Both modern industrial activities and natural systems release greenhouse gases (GHG) into the atmosphere. Through efficiency gains and improved soil management practices, farmers play a significant role in reducing our carbon footprint.
The most common source of GHG emissions is burning fossil fuels, so using energy more efficiently is one critical way to reduce emissions.
Soybean farmers use 35 percent less energy to produce a bushel of soybeans than they did in 1980, according to Field to Market review of USDA data, even though many embedded energy costs, like inputs, have increased. Studies cite decreases in soybean tillage, or disturbing the soil, as a key driver of this improvement.
“Soybeans adapt well to no-till and conservation-tillage systems,” says Tom Oswald, a soybean farmer from Cleghorn, Iowa. “Moving soil costs time and energy in the form of fuel and horsepower. My master’s degree research in the mid-90s demonstrated that tillage isn’t needed for competitive soybean yields on many soils, so all my soybeans are no-till and my fuel costs are minimal.”
Oswald is not alone in tilling soybeans less. USDA Farm Census data estimates that roughly 70 percent of U.S. soybean acres use some form of conservation tillage. In addition to using less fuel and making business sense, these systems reduce natural emissions from the soil.
“Tillage introduces oxygen to the soil, speeding up the biological conversion of the soil carbon complex to carbon dioxide. And without a crop growing, that carbon dioxide is released to the atmosphere,” explains Oswald. “Less tillage allows the soil to better balance its release of carbon with the crop growth it supports.”
The shift over time to less tillage has translated to notable GHG emission reductions. Emissions from soybean production decreased 45 percent, from 13.6 pounds CO2-equivalent gas per bushel in 1980 to 7.5 pounds in 2015, based on Field to Market calculations from USDA data. And the industry has committed to the goal of reducing emissions another 10 percent by 2025.
Carbon Sequestration Offsets Emissions
Agriculture can take a step beyond just reducing GHG emissions. Soil can store carbon, reducing concentrations of carbon dioxide in the atmosphere. This process, known as carbon sequestration, can actually offset the impact of GHG emissions.
“The prairies we farm naturally store carbon in plan and soil components,” Oswald says. “We are continually improving the balance between growing needed crops like soybeans with the soil system’s capacity to hold carbon.”
Much of that carbon is stored in organic matter, so practices and tools that increase soil organic matter, maintain soil stability and keep vegetation on the ground help sequester carbon.
“I’ve started adding cover crops where they make sense,” Oswald says. “The plants absorb carbon dioxide above ground and the roots maintain stability and increase organic matter under ground, mimicking the historical environment.”
Crop rotation, or changing what is planted in a field from year to year, lowers greenhouse gas emissions and increases yield, compared to planting the same crop each year, according to a University of Illinois study.
Oswald typically rotates between soybeans and corn, which use and release carbon and nitrogen — two basic soil components — differently.
“And, cover crops essentially add another season of rotation within this system, providing another way to store carbon,” he says.
He notes that genetically engineered (GE) seed has been instrumental in supporting reduced-till soybean systems. For example, soybean traits that provide a broader base of weed control tools reduce the need to break up the soil to manage weeds.
“As a farmer, my job is to help my crop contend against nature’s competitors like weeds, insects and diseases,” Oswald says. “GE seed helps me do that with less energy. And it helps soybeans adapt effectively to no-till management and other practices that boost organic matter.”
Farmers Improve Constantly
Ongoing adoption of the practices and tools Oswald relies on will support the soy industry’s continuous reduction in GHG emissions and overall sustainability. In the winter 2018 Soy Checkoff Producer Survey, 59 percent of farmers said they have changed production practices to increase the sustainability of their operation.
“We are learning how to manage our row crop systems to perform more like prairies, which improves soil health, supports carbon sequestration and maintains yield,” Oswald says. “Continuous improvement is part of farming, and we’ll never stop trying to get better.”
To learn more, follow Oswald on Twitter at @notilltom.