Submitted to: International Symposium on Animal Production/Environmental Issues
Publication Type: Proceedings
Publication Acceptance Date: 8/17/2001
Publication Date: 10/3/2001
Citation: Miller, D.N., Varel, V.H. 2001. Effect of nitrate and oxidized iron on the accumulation and consumption of odor compounds in cattle feedlot soils. In: International Symposium Addressing Animal Production and Environmental Issues, October 3-5, 2001, Research Triangle Park, North Carolina. p. 84-92.
Technical Abstract: We evaluated the use of amending NO3- and Fe(III) into mixtures of cattle feedlot waste as a way to minimize the production and persistence of odor compounds. In cattle waste slurries, nitrate proved most effective with no increase in VFA concentration (P > 0.05). Waste treated with iron accumulated VFA (171 micromoles/g soil), but it was less VFA than the fermentative control (229 micromoles/g soil). The persistence of VFA was also affected by the presence of alternate electron acceptors. In fermentative treatments, VFA persisted >41 days. In the iron and nitrate treatments, VFA persisted for only 16 and 2 days, respectively. Based upon these results, a pan study was conducted with dry feedlot waste amended with Fe(III), NO3-, or no electron acceptor (fermentative control). Odor compounds and electron acceptors were monitored before and after a simulated rainfall event followed by drying. Addition of alternate electron acceptors had significant effects on pH, ammonia, fecal coliforms, total VFA, and branched-chain VFA. Iron compared to fermentative treatments had increased malodorous VFA (10-fold higher), increased fecal coliform content (10-fold higher in the iron treatment), and decreased pH (6.2 versus 7.6). However, ammonia was greater, 240 micromoles g dry matter, in the iron treatments compared to controls which retained no ammonia. Nitrate was superior to the fermentative control in that 23% less branched-chain VFA was produced and a higher pH was attained (9.9 compared to 9.2). We conclude that amending cattle feedlot soils with alternate electron acceptors may prove effective at controlling odors after rainfall events. Nitrate amendment was the best short-term control on anaerobic odor compound production, but more research is needed before iron amendment is recommended as a viable solution.