K-State engineers find both a cause and a solution for greenhouse gases from silage

MANHATTAN — A team of Kansas State University researchers has identified silage as a significant yet overlooked source of nitrous oxide emissions, while simultaneously developing methods to dramatically reduce these greenhouse gases from agriculture.

Agriculture is the largest source of nitrous-oxide, or N2O, emissions in the U.S., with N2O being the third-most impactful greenhouse gas after carbon dioxide and methane. Despite its significance, silage — a moist, fermented plant material used to feed livestock — has been an underexplored source of N2O emissions.

The K-State research team — led by Jeongdae Im, associate professor of civil engineering — investigated the potential of silage as a contributor to N2O emissions. The team conducted experiments using simulated silage from three major crops commonly used in the U.S.: maize, alfalfa and sorghum. Over a four-week period, they monitored the emissions and found that all three types produced substantial amounts of N2O.

In a pivotal discovery, the researchers found that N2O emissions from silage primarily originate from denitrifying bacteria. Building on this insight, they tested the addition of chlorate—a known inhibitor of denitrification—to the silage. The results showed that adding chlorate significantly reduced N2O emissions across all tested crops.

This suggests that chlorate could serve as an effective additive in silage production to mitigate greenhouse gas emissions, offering new insights into microbial processes affecting greenhouse gas production.

“Our findings reveal that silage is a notable source of nitrous-oxide emissions, but more importantly, they highlight a practical solution to address this issue,” Im said. “By incorporating chlorate into silage additives, we can target the denitrifying bacteria responsible for these emissions.”

This research was supported by a National Science Foundation CAREER award, enabling the team to explore innovative strategies for reducing greenhouse gases associated with agriculture.

The study’s recent publication in PNAS Nexus underscores the importance of this work in advancing agricultural sustainability. The team hopes that their research will lead to further studies and the adoption of practices that reduce greenhouse gas emissions from silage production.

“This is an exciting step forward,” Im said. “We aim to continue this research to develop practical applications that can be readily implemented by farmers and the agricultural industry.”