Ammonia emissions during the initial phase of microbial degradation of solid and liquid cattle manure

Abstract

The maximum specific ammonia emissions from liquid manure (LM) and solid manure containing 2.5 kg straw/livestock unit (LU)/day (SM 2.5) or 15 kg straw/LU/day (SM 15) increased in the sequence LM < SM 2.5 < SM 15 (662.6 < 3163.7 < 6299.8 μg NH₃–N/h/kg). These emission levels were attained soon after the maximum temperatures (22.9°C < 34.3°C < 69.5°C) induced by microbial self-heating had been reached. After that, NH₄⁺ was microbially re-bound in amounts that increased with a higher C content and a widening C:N ratio, i.e. also in the sequence LM < SM 2.5 < SM 15. Over a period of 15 to 16 days, 6.0% (LM), 10.8% (SM 2.5) and 5.9% (SM 15) of the N_total was emitted. When the accumulated ammonia emissions were extrapolated beyond this period of investigation, it was concluded that, over longer storage periods, solid manure offers better biological conditions for low ammonia emissions than liquid manure.