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Practical means to decrease aerial emissions will enhance the ability of the US egg industry to improve environmental stewardship while continuing to provide consumers safe and affordable eggs. Ammonia emissions from manure-belt laying hen houses have been shown to be less than 10% of the emissions from high-rise counterparts where manure is stored in-house for a year. However, on-farm manure storage for manure-belt houses also emits NH3, which is a part of the total farm emissions. Nevertheless, treating manure in storage sheds to decrease NH3 emissions may be more readily implemented than treatment inside the layer houses because of potential bird health concerns and possible detrimental effects of the treatment on the housing equipment. The laboratory-scale experiments reported here examined the efficacy of 4 commercially available treatment agents, topically applied to laying hen manure at 3 different dosages, in decreasing NH3 emissions from the manure storage. The treatment agents included zeolite, 2 forms of Al+Clear (aluminum sulfate, 48.5% liquid and granular), Ferix-3 (ferric sulfate), and Poultry Litter Treatment (PLT, sodium bisulfate). All the tested agents showed appreciable NH3 emission reduction of 33 to 94%. In all cases, the greatest application dosage provided little additional NH3 reduction as compared with the medium dosage (P > 0.70). Comparison among the dry granular Al+Clear, Ferix-3, and PLT in reduction of NH3 emission over a 7-d manure storage period showed no significant difference when the agents were applied at 0.5 kg/m2 of manure surface area (P = 0.40) but greater reduction for Al+Clear (92 ± 3%) and Ferix-3 (90 ± 1%) as compared with PLT (81 ± 2%) when applied at 1.0 kg/m2 (P < 0.01). Further field verification tests of the laboratory-scale findings are warranted.