Forage conservation is a neglected nitrous oxide source

Agricultural activities are the major anthropogenic source of nitrous oxide ( $$ ), an important greenhouse gas and ozone-depleting substance. However, the role of forage conservation as a potential source of $$ has rarely been studied. We investigated $$ production from the simulated silage of the three major crops-maize, alfalfa, and sorghum-used for silage in the United States, which comprises over 90% of the total silage production. Our findings revealed that a substantial $$ could be generated, potentially placing forage conservation as the third largest $$ source in the agricultural sector. Notably, the application of chlorate as an additive significantly reduced $$ production, but neither acetylene nor intermittent exposure to oxygen showed any impact. Overall, the results highlight that denitrifiers, rather than nitrifiers, are responsible for $$ production from silage, which was confirmed by molecular analyses. Our study reveals a previously unexplored source of $$ and provides a crucial mechanistic understanding for effective mitigation strategies.