Effects of biochar application methods on ammonia (NH₃) volatilization from used broiler litter

Summary: Elevated ammonia (NH₃) emissions from litter are a concern in modern broiler production and can negatively influence performance and welfare. While commercially available litter amendments are commonly used to mitigate ammonia emissions, their effectiveness is often short-lived, prompting interest in more sustainable alternatives such as biochar. The objective of this project was to investigate the effects of different biochar application treatments (surface-applied vs mixed) on NH₃ volatilizations from used broiler litter. Biochar was surface-applied to litter at rates of 0.48, 0.97, 1.46, and 1.95 kg/m2 and mixed in at rates of 7.5, 15.0, 22.5, and 30.0 % v/v. Poultry Litter Treatment® (PLT) was surface-applied at a rate of 0.73 kg/m2 and a control of non-amended litter was also included. Treatments were replicated three times using a total of thirty 13.2 L plastic vessels. A constant air flow of 1.5 LPM was supplied to each vessel and either exhausted to the atmosphere or a photoacoustic NH₃ gas analyzer. NH3 was measured in each vessel nine times daily during a 12 d study. Mixing biochar into the litter provided enhanced contact with litter profile and led to significantly lower overall NH₃ concentrations than the surface-applied treatment (126 ppm vs 146.6 ppm, respectively). The 22.5 and 30 % v/v mixed applications resulted in the lowest NH3 concentrations (P ≤ 0.05) for the biochar treatments. However, NH₃ concentrations from all the biochar application treatments were significantly higher than PLT (65.0 ppm). This study shows that mixing biochar into broiler litter can reduce NH₃ volatilization. However, it does not seem to be competitive with PLT in terms of NH₃ reductions alone.