Findings suggest that modifying silage production could decrease the largest source of nitrous oxide emissions in the United States (from agriculture), and cut total greenhouse gas emissions by between 2%–4%.
The Silent Assassin: Silage
Silage has been largely overlooked as a potential source of this potent greenhouse gas, in part due to forms that are poorly quantified or understood for other emissions from crop production, including those resulting nitrogen cycling. Silage the moist, harvested plant material used to feed livestock during the winter that is preserved through fermentation.
This could contribute to significant N2O emissions from the silage-making process, as described in research recently published in PNAS Nexus. The investigators, led by Jeongdae Im and associates evaluated the N2O emissions from silage simulated from three primary crops used in the U.S.: maize, alfalfa and sorghum. It warns that during the four weeks of monitoring N2O emissions from all three crops was much higher than previously thought and that this means forage conservation could be the third largest source of agricultural N2O emissions.
Chlorate to the Rescue
Now, the researchers report a solution to this issue (good news)! Chlorate greatly suppressed N2O emissions from all crops tested, indicating that chlorate may function as a valuable silage additive to reduce carbon-footprint in harvested forage.
In English, the authors suggest that the N2O emissions from silage are most likely generated by denitrifying as opposed to nitrifying bacteria. Thet was shown by experiments involving chlorate and oxygen sensitivity as well as molecular studies. It is plausible that denitrification inhibitors such as chlorate could prove to be a key technology for lowering silage production emissions by arresting NO 3 − reduction to N2O by denitrifying bacteria.
Conclusion
The novelty of this study is that it shines its light on a rather overlooked sector in agriculture with respect to GHG emissions, namely silage production. By understanding the process of denitrification and flagging chlorate as a potential additive, a team of researchers has cleared new pathways for reducing the environmental impact of livestock farming. Put these strategies in place may very well be an important move to curb the role that agriculture plays in climate change.
