Temporal Nitrous Oxide Emissions from Beef Cattle Feedlot Manure after a Simulated Rainfall Event

Area of Science:

• Agricultural Science
• Environmental Science
• Atmospheric Chemistry

Background:

• Nitrous oxide (NO) is a potent greenhouse gas (GHG) originating from agricultural activities.
• Beef cattle feedlots are significant sources of atmospheric emissions.

Purpose of the Study:

• To quantify nitrous oxide-nitrogen (NO-N) emissions from simulated open-lot beef cattle feedlot pens following rainfall events.
• To establish a relationship between rainfall volume and NO-N emissions for improved modeling.

Main Methods:

• A recirculating-flow-through chamber system with a real-time NO analyzer was employed.
• Simulated rainfall (0–50.8 mm) was applied to manure in steel pans.
• NO-N emissions were monitored for 45 days post-rainfall.

Main Results:

• Two distinct NO-N emission episodes were observed: a short 10-hour episode and a prolonged 40-day episode.
• The second, longer episode accounted for the majority (69–91%) of cumulative NO-N emissions.
• A strong positive correlation was found between rainfall amount and cumulative NO-N emissions (r=0.99, P<0.001).

Conclusions:

• Rainfall is a critical factor driving NO-N emissions from beef cattle feedlots.
• The established rainfall-emissions relationship aids in modeling annual GHG emissions.
• Findings support the assessment of management practices to mitigate feedlot emissions.