You can choose between liquid or powder stall deodorizing products.

Most of us take pride in having a clean barn and pat ourselves on the back that there’s no offensive odor—at least to fellow horsemen. However, you may not realize that even though you can’t actually "smell" anything, there’s a constant release of gases from manure and urine that can assault your horse’s lungs.

Most studies implicate fine particulate matter and endotoxins in the air as the primary factors, and they are indeed important. However, ammonia concentrations at the floor level are much higher than in the barn air in general, and the horse will get a concentrated dose when down sleeping or resting. That’s where stall fresheners and deodorizers truly have a place in wise barn management. It’s simply a matter of good health.

How Do They Work?
Step one for a fresh, healthy barn is plain old stall cleaning. That means keeping stalls well picked out and the removal of soaked bedding and pooled urine. Good ventilation is also extremely important. However, that still won’t completely eliminate ammonia. Ammonia is produced by bacterial breakdown of urea in urine and unabsorbed protein in manure. Stall-freshener products are designed to give you extra ammonia control.

Simply absorbing urine helps reduce ammonia by making the urea less available to bacteria. For example, stalls with paper-based beddings have less ammonia than stalls with straw. Diatomaceous earth is also highly absorbent.

Stall fresheners go one step further when they’re mineral-based. Zeolites, montmorillonite and Bentonite (which is primarily montmorillonite) clays actually chemically bind ammonia molecules. This binding process is called adsorption.

Montmorillonite can bind both urea and ammonia, but binds them irreversibly. Zeolite binds only ammonia (urea isn’t the odor problem), but can release it again so it acts as a slow nitrogen fertilizer for soil. Of the two, our testers thought the zeolite gave better ammonia odor control, but montmorillonite absorbed more moisture.

Yucca saponins have been proven to reduce ammonia production, although the exact mechanism is unclear. Natural-source adsorbents and adsorbents from plants may also be used.

Since the production of ammonia depends on bacteria, a variety of approaches gear ingredients toward the bacteria. Stall Dry Plus contains a chemical antimicrobial.

Two spray-on products take the opposite approach by supplying live bacteria that will breakdown ammonia and other organic waste products. Surfactants also disrupt bacteria. Enzymes may be added to help breakdown of ammonia and other malodorous wastes in manure.

Mucking stalls releases ammonia and stirs up dust, mites and mold spores. Finely ground stall fresheners are also potentially irritating to you and your horse. Try to remove your horse from his stall during stall cleaning, if possible, especially if you’re using a powdered deodorizer, and keep the barn well-ventilated.

Stall Fresh helped us save bedding and reduced odor and wetness.

Our Trial
We did our trial in winter, in a small barn of four to six horses that was closed up, except for traffic in and out. Horses were stall-confined except when being exercised. Products were used according to manufacturer’s recommendations, with any modifications we found necessary for best results listed in the chart.

The products fell into two general categories, those that only addressed odor and those that also offered significant moisture absorption, which means less bedding needs to be removed. We tested using both shavings and straw. All soaked bedding was removed daily and urine spots taken down to stall bottom.

You’ll get more punch for your pennies if you use a stall freshener that is also highly absorbent. We found savings in bedding added up from 20 to 30% for Sweet PDZ, Stall Dry and Stall Fresh, respectively.

Bottom Line
All the products were effective in reducing ammonia odor. Gateway’s Su-Per Odor Eliminator was a standout for price at 14¢/day and should help speed composting. However, the down side is that mixing and misting takes longer than sprinkling powder and you’re working with live—although not harmful except perhaps on open wounds—bacteria. It’s also good for freshening trailers between cleanings.

Sweet PDZ and Stall Dry Plus did somewhat better on controlling ammonia, but we’re not sure if the antimicrobial in Stall Dry Plus would interfere with composting (and the company representative didn’t know either), if that’s an issue for you.

Overall, it was close match between Stall Dry and Stall Fresh on bedding savings, but over a one-month period we used approximately 5% less bedding with Stall Fresh than Stall Dry and cost was better as well. Therefore, Stall Fresh gets the nod as our No. 1 choice.

Kaeco’s Stall Power was the most economical of the powders if odor control is your main objective, earning our Best Buy.