The American Farmland Trust recently released a report showing the adoption of no-till practices and planting cover crops could reduce nitrous oxide (N2O) emissions for a net reduction in greenhouse gas (GHG) emissions and increase soil carbon sequestration.
The report states the adoption of these regenerative agriculture practices on 70 percent of the cropland is the equivalent of removing 53 million cars from the road. According to the report and the Environmental Protection Agency, agriculture contributes 9.3 percent of total GHG emissions, and 55 percent of that is due to N2O emissions from fertilization, manuring and growing legumes. Emissions from ruminant livestock and manure management—in the form of methane—account for 42 percent of agriculture emissions.
With nearly 400 million acres of cropland in the U.S., “the country has an opportunity to rebuild soil organic carbon (SOC), and rebuilding soil health is crucial to sustaining agriculture, enhance the profitability of farmers and ranchers, and combat the impacts of climate change,” the report states.
“Our hope is to combat climate change by building broad coalitions that include farmers and ranchers, and rural communities as part of the solution. We look to individuals, policymakers, government leaders, and all of society to help make this dream come true,” said Jennifer Moore, climate initiative director for the American Farmland Trust, in a press release.
The report describes the planting of cover crops can build SOC and remove carbon dioxide from the atmosphere by keeping the soil from being bare, which adds carbon to the soil. Cover crops promote microbial communities that, when they die, break down into carbon-rich compounds. “The combination of active roots and sticky microbial compounds hold the soil together in small clumps called aggregates, which are resistant to disturbance by wind, rain, and tillage,” the reports read. However, the report notes that planting non-legume cover crops versus legume cover crops effectively reduced N2O emissions. Additionally, cover crop incorporation into the soil through tillage increased N2O emissions, demonstrating the need for both conservation practices.
No-till practices are shown to decrease N2O emissions and save money by reducing passes in the field, resulting in lower fuel and labor costs and wear and tear on the tractor. Studies in the report have shown “after a short transition period, no-till can produce similar crop yields to conventional tillage in many areas and cropping systems.” No-till can increase soil aggregate structure creating an environment where SOC can build up in both the upper surface within the root structure and in depths below 8-12 inches. However, some reports are mixed on whether no-till can sequester SOC through the entire soil profile.
The potential reduction in GHGs is significant, with roughly 178 million acres available for no-till implementation in U.S. croplands.
There is a learning curve with the adoption of these practices and increased costs with the initial purchase of equipment. The report articulates that farmers operating on tight margins and adopting these techniques present challenges in areas with minimal moisture and cold regions with long-season annual crops. Some solutions the report offers are adopting strip-till farming, using incentives to help farmers with financial risks, peer-to-peer information and equipment sharing, and modifying leases for risk-sharing in implementing these practices.
Lastly, the American Farmland Trust with the USDA Agriculture Research Service developed a tool to “quantify and visualize county-level net carbon dioxide equivalent (CO2e) reductions resulting from the implementation of a variety of cropland and grazing land management practices.” The tool called Carbon Reduction Potential Evaluation (CaRPE) Tool provides the estimated values for planning purposes. The CaRPE tool found the implementation of cover crops on 261 million acres—excluding hay land and other grasses—could reduce the equivalent of just over 19 million cars driven in a year or the energy use in one year for just over 19 million homes. Additionally, if 281 million acres implemented either no-till or strip-till practices, it would reduce the carbon dioxide equivalent for just over 34 million cars or the electricity use of 26.7 million homes for one year. Together, it would equate to a reduction equal to 40 percent of 2018 U.S. agricultural emissions. However, these figures are dependent on the theory that all the above acreage were to adopt these practices, and “universal adoption is not feasible.” The report shows if these practices were adopted on a smaller scale with no-till practices adopted on 34 million acres and cover crops on 35 million acres, the reduction would be the equivalent of 20.9 million cars driven for one year.
“Simply put, we need our farmers and ranchers not just to grow our food (and feed and fiber), but to provide environmental services, including climate change mitigation and adaptation capacity,” said Moore. — Charles Wallace, WLJ editor