A study evaluating different scenarios in corn production found that by applying fertilizer at optimal rates and using tillage practices that minimally disturb the soil, greenhouse gas (GHG) emissions can be dramatically reduced.

The farm-level study was conducted by researchers at Colorado State University and the University of Minnesota. The study evaluated thousands of scenarios. Detailed production data from farmers were analyzed to model carbon emissions under various scenarios while maintaining high yields.

A reduction in GHG can account for a significant reduction in the carbon footprint for corn production, the researchers report.

There was an original study in 2011 where researchers collected and analyzed detailed, three-year survey data from 40 large, family-owned farms supplying corn to a biorefinery in southwest Minnesota. The original study showed the respondents had a 25 percent lower carbon footprint than the U.S. average.

Now results from a current study of data comes from Colorado State University. The university researchers used the data from these Minnesota farms in its own model to assess the effect of thousands of best management practice scenarios.

“Greenhouse gas emissions could be reduced by 46 percent simply by limiting nitrogen fertilizer application from current rates of 225 kilograms (kg.) per hectare (ha) to the optimal rate of 150 kg,” the researchers contend in their report.

“In addition, by using minimal tillage practices, carbon emissions could be reduced 65 percent compared to current practices. If fertilizer application rates were managed at the 150 kg/ha rate and no-till practices were used, the CSU model showed carbon sequestered at the rate of 55 grams of carbon per bushel of corn,” the announcement of results further suggests.

“A lot of studies have been done to develop recommendations for what corn farmers should do to be more sustainable,” said John Sheehan, a researcher in the Department of Soils and Crop Sciences at CSU who was the principal author of the study. “For these studies, we started by asking them what they were doing and found that some farmers were already managing their land in ways that lead to greatly reduced and even negative carbon footprints. In the modeling study, we analyzed what would happen if all farms in our original survey adopted the best of these practices.”

The CSU team, led by CSU soil and crop sciences professor Keith Paustian, included Kendrick Killian and Stephen Williams of the Natural Resources Ecology Laboratory in the Warner College of Natural resources at CSU. A review panel included experts from the World Wildlife Fund, The Nature Conservancy and the Environmental Defense Fund. The study was sponsored by Huttner Strategies, LLC, with funding provided by The Coca-Cola Company.

Applying less nitrogen fertilizer was one of the main ways Minnesota farmers reduced their emissions, Sheehan explained. Nitrogen fertilizer not only requires a vast amount of energy that leads to emissions during manufacturing, it also emits nitrous oxide, a potent greenhouse gas.

“Over-application of nitrogen fertilizer can add a lot of nitrous oxide, which has a huge greenhouse-gas impact,” Sheehan said.

Links to the studies

“Measuring the carbon footprint of Gevo, Inc.’s Luverne MN corn supply,” November 2012, Sheehan, et.al., Institute on the Environment, Univ. of Minnesota, Colorado State University. http://iree.environment.umn.edu/wp-content/uploads/2014/03/Gevo-final-report-1.pdf

“Scenarios for low carbon corn production,” March 2014, Sheehan, et.al., The Natural Resources Ecology Laboratory, Colorado State University