Gas emissions during cattle manure composting and stockpiling

Area of Science:

• Agricultural Science
• Environmental Science
• Atmospheric Chemistry

Background:

• Manure composting is a standard practice in cattle feedlots.
• Gaseous emissions from manure management are not fully understood.
• Quantifying emissions is crucial for environmental impact assessment.

Purpose of the Study:

• To quantify ammonia (NH3), nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) emissions.
• To compare emissions from windrow composting (turning) versus static stockpiling (nonturning) of manure.
• To assess nitrogen and carbon losses during manure management.

Main Methods:

• An inverse-dispersion technique using an open-path Fourier transform infrared (OP-FTIR) spectrometer.
• Continuous gas sensing over a 165-day study period at a commercial feedlot.
• Flux calculations based on collected data intervals for both management methods.

Main Results:

• Windrow composting showed higher nitrogen loss as ammonia (26.4%) and nitrous oxide (3.8%) compared to stockpiling (5.3% and 0.8%).
• Carbon loss as carbon dioxide and methane was substantial in both methods, with stockpiling showing higher percentage loss (54.8% C).
• Total greenhouse gas emissions from windrow composting were 2.7 times greater than from static stockpiling.

Conclusions:

• Manure management practices significantly influence gaseous emissions.
• Windrow composting leads to substantially higher greenhouse gas emissions than static stockpiling.
• Reducing ammonia and nitrous oxide emissions can improve nitrogen retention and lower the overall greenhouse gas footprint of manure management.