Looking back to look ahead: a vision for soil denitrification research

Denitrification plays a critical role in regulating ecosystem nutrient availability and anthropogenic reactive nitrogen (N) production. Its importance has inspired an increasing number of studies, yet it remains the most poorly constrained term in terrestrial ecosystem N budgets. We censused the peer-reviewed soil denitrification literature (1975 to 2015) to identify opportunities for future studies to advance our understanding despite the inherent challenges in studying the process. We found that only one-third of studies reported estimates of both nitrous oxide (N2O) and dinitrogen (N2) production fluxes, often the dominant end products of denitrification, while the majority of studies reported only net N2O fluxes or denitrification potential. Of the 236 studies that measured complete denitrification to N2, 49% used the acetylene inhibition method; 84% were conducted in the laboratory; 81% were performed on surface soils (0-20 cm depth); 75% were located in North America and Europe; a...