Cover crop residue decomposition triggered soil oxygen depletion and promoted nitrous oxide emissions.

Cover cropping is a promising strategy to improve soil health, but it may also trigger greenhouse gas emissions, especially nitrous oxide (NO). Beyond nitrogen (N) availability, cover crop residue decomposition may accelerate heterotrophic respiration to limit soil O availability, hence promote NO emissions from denitrification under sub-optimal water-filled pore space (WFPS) conditions that are typically not conducive to large NO production. We conducted a 21-day incubation experiment to examine the effects of contrasting cover crop residue (grass vs legume) decomposition on soil O and biogeochemical changes to influence NO and CO emissions from N labeled fertilized soils under 50% and 80% WFPS levels.