A reduction in the emission of malodorous gases from liquid hog manure (LHM) would represent an advantage for LHM use in agricultural systems. Procedures for the reduction of disagreeable odors during storage of LHM (Sus scrofa domesticus) were studied in the laboratory. Sphagnum peat moss (Sphagnum moss species), 1.5 M H2SO4, 1.7 M H3PO4, monocalcium phosphate monohydrate (MCPM), elemental S, CaCO3, and CaO were used to reduce odors. Amended and nonamended LHM was incubated with and without aeration for periods ranging from 2 to 720 h at 23 +/- 0.4 degrees C. Odor measurements of emitted air were carried out using a sensory panel. Gas chromatography-mass spectrometry (GC-MS) was used to identify specific odor-producing compounds. The GC-MS analysis revealed that added Sphagnum moss (SM) prevented the release of 1,2-ethanediamine, N-methyl methanamine, 3-methyl 2-butanamine, methyl hydrazine, ethanethioic acid, and methanethiol from LHM. Aeration as a treatment, in general, resulted in a greater reduction of odor presence and offensiveness than nonaeration. In nonaerated LHM treatments, SM at levels of 4 or 8% (w/w) or a combined treatment of 2% CaCO3 plus 1% SM resulted in a significant reduction in odor presence and offensiveness. Little odor reduction was observed with H2SO4, H3PO4, MCPM, and CaO, and no odor reduction was found with elemental S.