The Potential of Best Management Practices to Reduce N2O Emissions.

The agricultural sector is the largest global anthropogenic source of N₂O, a powerful greenhouse gas with a global warming potential 298 times that of CO₂. Because 92% of agricultural N₂O emissions are derived from soil and nutrient management practices, changes in management practices have great potential to mitigate – or exacerbate – agricultural N₂O emissions. We have been investigating the potential of tillage and manure application methods to reduce N₂O emissions, with a focus on conventional versus no till systems and broadcast versus manure injection. Through a number on on-farm and laboratory experiments, we have found that, while tillage practice has little impact on N₂O emissions, manure injection increases N₂O emissions relative to broadcast. If manure application is in the fall, elevated N₂O emissions may continue in to the winter. In contrast, spring manure application seems to result in shorter-lived N₂O pulses. Finally, even with spring-only manure application, the effects of injection are seen during spring thaw and freeze-thaw cycles, where soils with manure injection released nearly double the amount of N₂O than soil with broadcast manure application. Our results suggest that management can dramatically impact N₂O emissions, and that these management decisions may interact with warmer winters to further increase N₂O emissions.