ARS | Publication request: Nitrification in Beef Cattle Feedlot Soils

Submitted to: Microbial Ecology International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: April 7, 2008
Publication Date: August 17, 2008
Repository URL: http://www.kenes.com/isme12Posters/1858.htm
Citation: Miller, D.N., Rice, W.C., Woodbury, B.L. 2008. Nitrification in Beef Cattle Feedlot Soils [abstract]. Microbial Ecology International Symposium. Poster No. 0289. Available: http://www.kenes.com/isme12/Posters/1858.htm

Technical Abstract: Background and Aims: Ammonia volatilization is the primary route for nitrogen loss from cattle feedlots. An additional, but poorly studied mechanism in feedlots is aerobic nitrification. The aim of this study is to characterize nitrifier activity, abundance, and diversity for a cattle production cycle. Methods: Soil samples were collected over a nine-month period from three sites within a cattle feedlot pen (feed bunk, central mound, and down gradient). Potential activity, cultivable nitrifier abundance, and molecular diversity were measured using chlorite inhibition, most-probable-number, and PCR/DGGE analysis, respectively. Results: Potential activity and ammonia-oxidizing bacteria (AOB) per gram dry soil varied by site and throughout time (below detection to 1.6 micromoles hour-1 and from below detection limit to 108 AOB). Nitrite-oxidizing bacteria (NOB) were typically 10-fold higher abundance compared to AOB. Correlations were generally weak among nitrification measures and soil parameters, but much stronger between nitrifying activity and denitrifying activity (r = 0.300) or AOB (r = 0.343) and between AOB and NOB (r = 0.306). AOB and NOB community analysis revealed substantial changes with time and between locations. Conclusions: This initial investigation indicates that the nitrifier community was spatiotemporally dynamic, abundant, and showed high potential nitrifying activity, especially compared to other soil systems. Thus, nitrogen fate in cattle feedlot soils may not be entirely determined by ammonia emission.