Penn State Study Shows Benefits of Livestock Odor Control

By Blake Jackson

Humic manure additives are one tool that can be incorporated into a broader strategy for reducing and controlling livestock odors.

A Penn State demonstration project on a full-scale swine finishing operation showed that a humic-based additive significantly reduced odor emissions.

This effect was observed both from barn ventilation exhaust and from field-applied swine manure. However, these results cannot be universally applied to all additives or scenarios, and producers should exercise caution in assuming that similar outcomes will occur under different conditions.

Odor complaints from animal production facilities are increasingly common as residential areas expand into rural regions. Malodors arise from manure collection, storage, transport, and disposal, and can threaten the viability of farming operations.

While advanced treatments such as anaerobic digestion and solids separation are effective, they are often expensive and require specialized expertise. Simpler approaches like diet adjustments and manure additives are more accessible, though their effectiveness is inconsistent.

Odor control additives work in several ways: they may alter the odor itself through masking agents, act on microbial communities responsible for odor production, or change the physical-chemical environment to limit gas release.

Some additives contain bacteria or enzymes to enhance microbial breakdown of odorous compounds, while others use adsorbents to trap gases or adjust pH to suppress specific odors. Despite these options, no additive fully eliminates odors, and results often vary depending on conditions.

To measure effectiveness, olfactometry using human assessors remains the most reliable method. Field and laboratory approaches involve diluting odorous air with clean air and determining the threshold at which odors are detectable.

These measurements allow calculation of odor emission rates (OER), which quantify the release of odors from ventilated housing.

In the Penn State demonstration, two 2,250-pig tunnel-ventilated barns on the same farm were used. One barn’s underfloor manure pit received monthly applications of the humic additive, while the other barn remained untreated.

After 20 weeks, the treatments were switched for further evaluation, allowing researchers to assess the additive effect under real farm conditions.

Photo Credit: istock-deyanarobova