See more from this Session: Microbial Responses to the Environment: I
Monday, November 1, 2010: 2:05 PM
Long Beach Convention Center, Room 104B, First Floor
A wide variety of volatile odor compounds accumulate during the anaerobic fermentation of livestock wastes. Since these compounds are easily degraded in other environments when alternate electron acceptors (compounds other than O2) are available, we evaluated the use of amending NO3- and Fe(III) into mixtures of cattle feedlot manure as a way to minimize the production and persistence of odor compounds. Pan incubations were conducted with dry feedlot waste amended with Fe(III), NO3-, or no electron acceptor (fermentative control). Over several days, odor compounds and electron acceptors were monitored before and after a simulated rainfall event. Addition of alternate electron acceptors affected many of the measured soil parameters including pH, ammonia content, fecal coliforms, H2 gas production, total VFA, and branched-chain VFA. Compared to the standard fermentative control, iron treatments exhibited a three to four-fold increase in malodorous VFA content (6 to 8 mg VFA/g dry soil), increased fecal coliform content (10-fold higher), and decreased pH (2 unit decrease), which would greatly enhance VFA emission. However, one positive for the iron treatment was its greater ammonia content (>3 mg N/g dry soil) compared to controls which retained no ammonia. The nitrate treatment was superior to controls (and iron treatments) based upon its 100-fold lower fecal coliform content, high final pH (9.9), and its low content of branched-chain VFA. We conclude that nitrate amendment was the most effective for short-term control of many manure issues, while application of iron amendment may not prove to be a viable odor solution without further research because of the excessive accumulation of branched-chain VFA and coliform bacteria.