Can Farms Produce to the Max and Still Reduce Greenhouse Gas Emissions?

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June 27, 2022

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by Kristen Mally Dean (Argonne National Laboratory) Decarbonizing agriculture is critical for the U.S. to reach net zero emissions by 2050. A new data-driven approach looks at practices that are good for the earth and profitable for farmers. -- The world relies on American farmers to do much more than set its tables. In addition to producing food for people and animals, American farmers produce feedstocks for biofuel production.

In the process of doing this, the agricultural industry contributes about 10% of U.S. greenhouse gas (GHG) emissions. Because the amount of land dedicated for agriculture is limited, farmers need to find more ways to operate efficiently, sustainably and profitably while also reducing GHG emissions. With new practices, farmers can make farms a net sink of CO₂, helping the U.S. reach its goal of achieving net zero emissions by 2050.

“We want to give farmers, regional planners and others in agricultural management a tool to calculate how to use land sustainably and get the most value out of the land, which furthers both profitability and environmental goals.” — Troy Hawkins, group leader of fuels and products in Argonne’s Energy Systems and Infrastructure Analysis division

Sustainable intensification is a two-prong approach many think could help. It tries to optimize land use and management practices for maximum farmland productivity at the same time it tries to minimize associated environmental impact. The trick is finding the right balance between the two objectives.

Scientists who specialize in agroecosystems modeling and life-cycle analysis (LCA) from Colorado State University (CSU) and the U.S. Department of Energy’s (DOE) Argonne National Laboratory took a new analytic approach to the issue in a recent study of corn and soy farming in Iowa. They co-authored an article, “A multi-product landscape life-cycle assessment approach for evaluating local climate mitigation potential,” in the June 20 issue of the Journal of Cleaner Production.

“The concept of sustainable intensification of farming was applied into more broadscale landscape application,” said one of the article’s co-authors, Hoyoung Kwon, a principal environmental scientist in Argonne’s Energy Systems and Infrastructure Analysis (ESIA) division. “We considered productivity and GHG emissions, attempted to optimize land management tactics and products, and investigated different trade-offs that improve the land and land productivity.”

Many farms today are large, industrial farms that are high-tech and rely on high resolution data. Energy systems scientists at Argonne and CSU are studying sustainable intensification strategies to help them make profitable decisions while also reducing GHG emissions. (Image by Shutterstock/Saverio blasi.)

For example, farmers can clear and repurpose corn crop residue (or “stover”) for biofuel, but a percentage of stover can remain in the soil for valuable nutrient and carbon sources for future crops. Farmers can plant cover crops during the winter (or “fallow”) season, to supplement removed stover. The authors took into account energy, which has an emissions cost of planting of cover crops to holistically address net benefits of stover removal and cover crop planting. Farmers can also reduce how much land they till after a growing season ends, which lessens decay and reduces the amount of CO₂ that emanates from the soil. However, the farmer has to till some of the land to be ready for the next growing season.

While some farmers already follow one or even all three of these practices, the scientists from Argonne believe a better understanding of their impact will motivate more to do so, for real benefit.

“Our approach gives a holistic perspective and looks at the perspective of the farmer: What are all the products that can be produced on the land and what are the sustainability benefits?” said co-author Troy Hawkins, group leader of fuels and products in Argonne’s ESIA division. “Farming can be a risky, low-margin exercise. Profitability will always be a primary focus. However, sustainability has value that may be unrecognized. How can we put all that together with changes to land management practices to make farming more sustainable and improve farmers’ costs?”

At the end of the growing season, integrated approaches that include winter cover cropping and/or tillage intensity reduction would increase carbon in the soil, improve farm profitability and mitigate more GHGs, according to a new study by energy systems scientists at Argonne and CSU. (Image by Shutterstock/lourencolf.)

The scientists looked at the trade-offs and synergies between sustainable intensification and carbon-sequestering conservation measures in a real-world scenario. They used two models — DayCent and the Greenhouse Gases, Regulated Emissions, and Energy Use in Technologies (GREET) LCA — to evaluate a farming area upstream of Des Moines, Iowa.

The DayCent model represents daily flows of carbon, nitrogen and water between the atmosphere, vegetation and soil in natural and agricultural ecosystems. The scientists relied on it to evaluate GHG emissions in corn ethanol production and the effects of residue harvest.

They used GREET to account for emissions associated with farm operations and the use of harvested corn grain, soybean and corn stover as feedstocks for biofuel production. GREET is widely used across industries to evaluate energy consumption, GHG emissions, air pollutant emissions and water consumption associated with biofuel supply chains and other transport and energy technologies. Fellow co-author Michael Wang, Argonne’s interim division director for energy systems and Infrastructure, is a primary architect of GREET.

According to the study, harvesting 30% of the corn stover for biofuel production would increase farm revenues, double net profitability and increase overall biofuel production from the landscape by 17–20%. Removal of the stover would also mitigate GHGs somewhat, but it reduced the baseline amount of good carbon in the soil by 40%. In comparison, integrated approaches that include winter cover cropping and/or tillage intensity reduction would increase carbon in the soil, improve farm profitability and mitigate more GHGs.

“We focused on corn and soy but our approach could be extended to other crops,” said Hawkins. “Many farms today are large, industrial farms that are high-tech and rely much more on high resolution data. We want to give farmers, regional planners and others in agricultural management a tool to calculate how to use land sustainably and get the most value out of the land. This will further both profitability and environmental goals.”

The work was supported, in part, by DOE’s Bioenergy Technologies Office within the Office of Energy Efficiency and Renewable Energy.

The Office of Energy Efficiency and Renewable Energy’s (EERE) mission is to accelerate the research, development, demonstration, and deployment of technologies and solutions to equitably transition America to net-zero greenhouse gas emissions economy-wide by no later than 2050, and ensure the clean energy economy benefits all Americans, creating good paying jobs for the American people — especially workers and communities impacted by the energy transition and those historically underserved by the energy system and overburdened by pollution.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.

The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science. READ MORE

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An unfortunate consequence of this effort to reduce methane is discussion – though narrow in scope to date – that targets the livestock industry for cutbacks. A paper issued by the Changing Markets Foundation, a European based organization that characterizes itself as a proponent of using markets to meet sustainability challenges, contends that if the EU can persuade 10 percent of its citizens to switch to diets containing less meat and dairy, a 34-percent reduction in methane emissions could be reached.

It’s a shoot-from-the-hip proposition from an organization that fails to understand any move to reduce the number of animals as a way of reducing GHG emissions will only displace meat, egg and dairy production to other countries that have even higher GHG emissions compared to EU agriculture. Furthermore, such a wrong-headed move would have the unintended consequence of reducing important and critically needed sources of protein and nutrients from EU diets.

The report acknowledges that methane emissions from EU agriculture have fallen 4 percent in recent years. That number is expected to improve as more and more livestock operators adopt climate-conscious practices, such as using high-quality feed that reduces methane released from enteric fermentation, as well as managing manure to reduce the release of methane and nitrous oxide, including covering manure storage facilities.

Frank Mitloehner, a professor and air quality Extension specialist with the University of California, says that when a gas such as methane – known as a flow gas – is emitted, it is stagnant and an equal amount of the gas is destroyed at the same rate that it is put into the atmosphere. For that reason, he said, it is possible to reduce warming and other impacts to the climate by reducing the amount of methane produced.

Efforts to reduce methane emissions by livestock operators are paying off, with releases falling in manner reflective of a decrease in dairy cows, which now number some 9 million compared to 25 million a decade ago. Even with fewer numbers, the sector continues to produce the same amount of dairy products that it did with nearly three times fewer animals.

In looking at the global methane picture, it’s important to remember that the world’s three largest emitters – China, Russia and India – have yet to make a commitment to reducing their release of this potent GHG. Together, they make up about one-third of all methane emissions. While U.S. officials said last year that Russia had shown interest in joining the methane-reduction effort, that was before war in Ukraine broke out.

Here in the United States according to the White House, the federal government is taking a different approach embracing the expansion of voluntary adoption of climate-smart agriculture practices that will reduce methane emissions from key agriculture sources by incentivizing the deployment of improved manure management systems, anaerobic digesters, new livestock feeds, composting, and other practices.

Farmers, ranchers and forestland owners are showing they are taking seriously the threats posed by a changing climate. Strong and effective efforts in the agriculture sector – and particularly among livestock operators – are showing success in bringing down methane emissions, all while simultaneous providing ecosystem service benefits. USDA’s approach of spurring producers to voluntarily adopt the management practices and systems that reduce their methane footprint will have significantly better results than mandating measures that fail to recognize each operation’s location, means of production and its net benefits to society. READ MORE