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A major concern of the broiler industry is the volatilization of ammonia (NH3) from the mixture of bedding material and broiler excretion that covers the floor of broiler houses. Gypsum has been proposed as a litter amendment to reduce NH3 volatilization, but reports of NH3 abatement vary among studies and the mechanism responsible for decreasing NH3 volatilization is not well understood. The goal of this study was to evaluate the effect of adding 20 or 40% flue-gas desulfurization gypsum (FGDG) to broiler litter on pH, electrical conductivity (EC), water potential, urea-degrading bacteria abundance, NH3 and carbon dioxide (CO2) evolution, and nitrogen (N) mineralization in several 21-d experiments. The addition of FGDG to broiler litter increased EC by 24 to 33% (P < 0.0001), decreased urea-degrading bacteria by 48 to 57% (P = 0.0001) and increased N mineralization by 10 to 11% (P = 0.0001) as compared to litters not amended with FGDG. Furthermore, the addition of FGDG to broiler litter decreased NH3 volatilization by 18 to 28% (P < 0.0001), potentially resulting from the significantly lower litter pH values compared to un-amended litter (P < 0.0001). Findings of this study indicate that amending broiler litter with 20% FGDG can decrease NH3 volatilization and increase the fertlizer value of broiler litter. [ABSTRACT FROM AUTHOR]

Under laboratory conditions we studied the possibility of decreasing NH3 emissions from broiler litter by applying one of two nitrifier seeds (a material obtained from the top centimeters of the dirt floor of a chicken house, or Houston Black clay soil) at 0, 2.5, 5, and 10% w/w. Ammonia emission rates, total NH3 trapped in 0.1N H2SO4, and NOx--N concentrations decreased at the highest application rate of either amendment, whereas CO2 emissions increased with the amendments' application rates. We hypothesize that the lack of a significant increase in NOx--N concentrations was due to inhibition of nitrifiers by high NH4+-N, salt and Cl- concentrations, and denitrification promoted by high water, availability of easily decomposable carbon sources, and limited O2 supply. [ABSTRACT FROM AUTHOR]