Effect of Poultry Litter Amendments on Ammonia Emissions and Soluble Phosphorus

Background and Objective: Poultry litter amendments are widely used to mitigate ammonia (NH₃) volatilization, and some amendments, such as aluminum sulfate (alum), also reduce litter-soluble phosphorus (P), thereby potentially decreasing P runoff and leaching. However, the increasing cost of alum has prompted interest in alternative amendments that can simultaneously reduce NH₃ emissions and P solubility. This study evaluated the effects of several poultry litter amendments, including alum mud litter amendment (AMLA), a byproduct of alum production, and TPX, a calcium silicate nanoparticle with high P adsorption capacity, on NH₃ emissions and soluble P concentrations in poultry litter.

Methodology: A pen trial was conducted to evaluate six treatments: (1) untreated poultry litter (control), (2) alum-treated litter, (3) sodium bisulfate (SBS)-treated litter, (4) AMLA-treated litter, (5) alum plus TPX, and (6) SBS plus TPX. Cumulative NH₃ fluxes, litter-soluble P concentrations, and other relevant litter and bird health parameters were assessed.

Results: Compared with the untreated control, cumulative NH₃ fluxes were reduced by 70%, 65%, 63%, 63%, and 56% in the alum, SBS, AMLA, SBS plus TPX, and alum plus TPX treatments, respectively. At the end of the trial, alum plus TPX, alum, and AMLA reduced litter-soluble P concentrations by 63%, 56%, and 52%, respectively, relative to the control. In contrast, SBS and SBS plus TPX increased litter-soluble P concentrations by 18% and 6%, respectively, although substantially higher concentrations were observed earlier in the grow-out period. The addition of TPX had no significant effect on cumulative NH₃ emissions or litter-soluble P concentrations. Furthermore, SBS increased litter moisture and nitrous oxide (N₂O) emissions and was associated with poorer footpad and hock scores.

Conclusion: AMLA performed comparably to alum in reducing both NH₃ emissions and litter-soluble P concentrations, indicating its potential as an alternative poultry litter amendment. Although SBS effectively reduced NH₃ emissions, its effects on litter-soluble P, increased litter moisture and N₂O emissions, and poorer footpad and hock scores highlight potential environmental and bird welfare concerns. The addition of TPX provided no apparent additional benefit in reducing cumulative NH₃ emissions or litter-soluble P under the conditions evaluated.