Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2014
Publication Date: 3/2/2015
Citation: Waldrip, H., Todd, R.W., Cole, N.A. 2015. Can surface-applied zeolite reduce ammonia losses from feedyard manure? A laboratory study. Trans.ASABE 58(1):137-145.
Interpretive Summary: Ammonia gas can be lost from the manure in beef cattle feedyards. Ammonia from manure affects the health of air, soil, and water. Economical and practical ways are needed to reduce ammonia losses. Reducing ammonia loss would reduce environmental damage and increase the nutrient content of manure for plant fertilizer. Zeolite is a natural mineral that contains many tiny pores. These pores have a negative charge and attract ammonium and other compounds with a positive charge. This interaction is similar to the way metals are attracted to a magnet. Zeolite has been shown to lower ammonia losses and increase the nutrient content of animal manure. Very few studies have looked at how zeolite changes ammonia production from beef cattle manure. Applying zeolite on top of the manure in feedyard pens might be an economical way to reduce ammonia losses. We looked at ammonium retention by different types of zeolite. We also studied how zeolite application rate affected losses of ammonia from a simulated feedyard pen urine spot. In these studies we saw that ammonium retention by zeolite was rapid and complete after just 1 to 2 hours. The amount of ammonium retained by the zeolites differed with zeolite pH. When zeolite was applied to manure at different rates (0.5% to 10.0% of manure dry matter) the amount of ammonium retained was variable but was related to amount of zeolite applied. In another study, the application of zeolite to manure reduced ammonia losses by 42% compared to manure that did not contain zeolite. Zeolite has potential to lower ammonia losses at feedyards, but specific zeolite properties influence its effectiveness.
Technical Abstract: Ammonia emission from beef cattle feedyard manure results in losses of nitrogen (N), which may negatively affect air, soil, and water quality. The magnitude and rate of ammonia volatilization from feedyards partially depends on the amount of urinary urea excreted and dissociation of ionic ammonium into ammonia following urea hydrolysis. Zeolite clinoptilolite is a naturally occurring, porous aluminosilicate mineral that can sorb and sequester cations within its negatively charged framework structure. Zeolite has been used to mitigate ammonia losses and improve fertilizer value of compost, sewage sludge, and manure in livestock barns; however, few studies have evaluated its efficacy on open-lot beef cattle feedyards. Zeolite application to pen surfaces could be a practical and cost-effective means of reducing ammonia losses. Objectives of this study were to (1) characterize ammonium sorption by zeolites with differing physicochemical properties and (2) evaluate zeolite effects on rates and cumulative losses of ammonia following application of artificial urine to feedyard manure. Batch incubation studies with four commercially available zeolites revealed that ammonium sorption by zeolite was rapid (1 to 2 h) with large differences in sorption potential largely related to zeolite pH. Maximum sorption ranged from 28 to 97 cmol ammonium-N per kg zeolite. Effects of zeolite application rate [0.5% to 10.0% of manure dry matter (DM)] on sorption and desorption characteristics in a manure/artificial urine matrix were highly variable but tended to be proportional to zeolite application rate: as little as 0.5% zeolite increased ammonium-N recovery by up to 19%. In flow-through chamber studies, higher rates of zeolite did not reduce cumulative ammonia emissions, as 1.0% zeolite reduced cumulative ammonium emission by 42% and 5.0% zeolite reduced N losses by only 18% compared to unamended manure. Surface application of zeolite has potential for mitigating feedyard ammonia losses, but specific zeolite properties influenced its effectiveness. Further studies are warranted to evaluate effects of repeated zeolite application, co-application of zeolite and urease inhibitors, and cost:benefit of zeolite application at commercial feedyards.