Livestock manure is a substantial N₂O source, contributing approximately 16% of agricultural N₂O emissions globally. The emissions arise during manure storage, where nitrogen is converted through microbial processes, and after land application, where manure nitrogen enters the same nitrification-denitrification pathways as synthetic fertilizer.
Manure Management Systems
The magnitude of manure N₂O emissions depends strongly on the management system used. Liquid slurry systems stored in covered or uncovered tanks have different emission profiles than solid composting, pasture deposition, or anaerobic digestion systems. Anaerobic digesters, which capture methane for energy, can simultaneously reduce N₂O if the digestate is managed appropriately.
Pasture/range: 0.008–0.02
Solid storage: 0.005–0.015
Liquid slurry (open): 0.001–0.005
Anaerobic digestion: 0.0–0.002
Land application adds: 0.01 additional
Mitigation Opportunities
Improving diet formulation to reduce protein in animal feed directly decreases the nitrogen content of manure, reducing emission potential throughout the manure chain. Research suggests that matching dietary protein more precisely to animal requirements could reduce manure nitrogen excretion by 15–30% with minimal impact on productivity — a significant mitigation opportunity given the global scale of livestock production.