The effect of an acidified‐gypsum mixture on broiler litter urease‐producing bacteria and nitrogen mineralization

Abstract

Ammonia (NH 3 ) volatilization from broiler (Gallus gallus domesticus) litter is a microbially mediated process that can decrease bird productivity and serves as an environmental pollutant. The release of NH 3 is strongly influenced by the pH of litter. Flue-gas desulfurization gypsum (FGDG) has been suggested as a potential amendment to reduce NH 3 volatilization due to the pH buffering capacity of calcium carbonate (CaCO 3 ) precipitation. However, its effect on litter pH is not as pronounced as acidifying agents, such as aluminum sulfate (alum). The main objective of our study was to develop an acidified-FGDG amendment that has a more pronounced effect on litter pH and NH 3 volatilization than FGDG alone. We conducted a 33-d incubation in which litter pH, NH 3 volatilization, nitrogen mineralization, PLUP-ureC gene abundance, and CaCO 3 precipitation were measured. Treatments in the study included: broiler litter (BL), broiler litter + 20% FGDG (BL+FGDG), broiler litter + FGDG-alum mixture (BL+FGDG+A6), broiler litter + 6% alum (BL+A6), and broiler litter + 10% alum (BL+A10). Our FGDG+alum amendment decreased litter pH (0.68 pH units) and PLUP-ureC gene abundance (>1 log) compared with FGDG alone and the control (p < .05). This led to a 25% decrease in cumulative NH 3 loss after 33 d. The addition of FGDG alone did not have an effect on litter pH (p = .36) or cumulative NH 3 loss (p = .29) due to a lack of significant CaCO 3 precipitation.Treating litter with 6 and 10% alum was the most effective amendment for reducing pH and cumulative NH 3 loss.

Microbially induced calcium carbonate precipitation in broiler litter and its effect on soil pH

“…Previous research investigating CaCO 3 formation in gypsum-amended litter measured CaCO 3 produced by the microbial community (Burt et al, 2018(Burt et al, , 2021, which includes ureolytic fungi and bacteria, and ureolytic fungi can precipitate CaCO 3 via urea hydrolysis (Wong et al, 2020;Zhao et al, 2021). Therefore, the objectives of this study were twofold.…”

“…Molecular analysis of the microbial community in broiler litter indicates urease‐producing bacteria and fungi are abundant in broiler litter (49.6 ± 12.0 × 10 7 cells g −1 and 0.02 ± 0.00 × 10 6 cells g −1 , respectively), and ureolytic bacteria specific to litter facilitate urea hydrolysis in this material (Rothrock et al., 2008, 2010). In addition, the pH of broiler litter is typically ≥8.0 (Lacey et al., 2003), which is required for significant CaCO 3 precipitation in this material (Burt et al., 2021). Gypsum (CaSO 4 *2H 2 O) has been proposed as a litter amendment to reduce ammonia (NH 3 ) volatilization (Burt et al., 2017; Loch et al., 2011; Mishra et al., 2013; Oliveira et al., 2003, 2004; Sampaio et al., 1999) and increase broiler footpad health (Galli et al., 2021; Watts et al., 2017).…”