Changes in physicochemical properties and gaseous emissions of composting swine manure amended with alum and zeolite

Ammonia emissions from composted swine manure and the resulting physicochemical changes were monitored to determine the effectiveness of adding alum and zeolite during the composting process, as well as the most effective addition method. The two amendments reduced ammonia emissions 85?C92%, with the finished compost retaining three-fold more NH ₄ ⁺ -N than the unamended control. The addition of zeolite sequestered 44% of the retained NH ₄ ⁺ -N at zeolite exchange sites. The addition of amendments did not appear to significantly affect microbial activity, because the patterns of CO₂ emissions, total organic carbon (TOC) reduction, and the ratio of humic acid to TOC of amended and unamended composts were very similar. The final respiration rates and Solvita? maturity index indicated that the finished compost was well matured and aged. Alum has a high potential to reduce ammonia emissions and concomitantly enhance fertilizer N value. Zeolite further reduces ammonia emissions, and improves fertilizer quality, by serving as a slow-release N source.