Masking agents, deodorants, or perfumes have an odor stronger, and hopefully more pleasant, than the odor being masked. They are perhaps the most predictable and generally the most effective of the odor-control compounds. If used, they should be added just before transporting manure to a field. Odor-masking agents are best used on an intermittent basis, however, and only when severe problems are anticipated. After prolonged use, neighbors may find the masking agents more offensive than the original odors.
Counteractant chemicals interact with selected odors to reduce their intensity.
These compounds have had limited success due to the great variety of odorous gases. Oxidants and bacterial inhibitors include hydrogen peroxide, potassium permanganate, and ozone. They oxidize already formed odors and lessen odor production by reducing bacterial populations. None of the oxidants have been very successful, and the quantities required make the costs high. Chlorine and paraformaldehyde reduce odor by inhibiting anaerobic decomposition .