Changes in silage production could play a key role in reducing greenhouse gas emissions from agriculture. Currently, agriculture is the largest source of nitrous oxide (N2O) emissions in the United States. N2O is the third most impactful greenhouse gas, but one potential contributor—silage—has not been extensively studied. Silage consists of moist, harvested plant material used to feed livestock in winter, which is preserved through fermentation. During this process, anaerobic bacteria produce lactic acid, preventing spoilage. According to Jeongdae Im and colleagues, silage may be a notable source of N2O emissions.

The researchers, who published their findings in PNAS Nexus, estimated N2O emissions from simulated silage of three commonly used crops in the U.S.: maize, alfalfa, and sorghum. After monitoring these crops over a four-week period, they found that all produced significant levels of N2O. This suggests that forage conservation could be the third largest contributor to agricultural N2O emissions. Adding chlorate, however, significantly reduced N2O emissions from all three crops, indicating that chlorate could be an effective additive to decrease greenhouse gas emissions from silage production.

Their findings also suggest that N2O emissions from silage are primarily driven by denitrifying bacteria rather than nitrifying bacteria. This conclusion is based on experiments involving chlorate, varying oxygen levels, and molecular studies. The researchers propose that further exploration of denitrification inhibitors, like chlorate, could lead to a meaningful reduction in emissions from what now appears to be the third-largest source of agricultural N2O.