Nitrous Oxide Emissions from Open‐Lot Cattle Feedyards: A Review

Abstract

Nitrous oxide (N 2 O) emissions from concentrated animal feeding operations, including cattle feedyards, have become an important research topic. However, there are limitations to current measurement techniques, uncertainty in the magnitude of feedyard N 2 O fluxes, and a lack of effective mitigation methods. The objective of this review was to assess N 2 O emission from cattle feedyards, including comparison of measured and modeled emission rates, discussion of measurement methods, and evaluation of mitigation options. ). This variation was due to inconsistency in measurement techniques as well as irregularity in N 2 O production and emission attributable to management, animal diet, and environmental conditions. Based on this review, it is clear that the magnitude and dynamics of N 2 O emissions from open-lot cattle systems are not well understood. Further research is required to quantify feedyard N 2 O fluxes and develop costeffective mitigation methods.

Temporal Nitrous Oxide Emissions from Beef Cattle Feedlot Manure after a Simulated Rainfall Event

“…Redding et al (2015) measured N 2 O‐N emissions from two Australian beef cattle feedlots, reporting mean N 2 O‐N emissions of 0.0026 and 0.27 kg ha −1 d −1 (two orders of magnitude difference). Waldrip et al (2016) reported highly variable N 2 O‐N fluxes among published studies on open‐lot beef cattle production systems. Some of this variability could be attributed to climatic and management differences among feedlots, in addition to differences in the specific method used to measure N 2 O emissions.…”

Nitrous Oxide from Beef Cattle Manure: Effects of Temperature, Water Addition and Manure Properties on Denitrification and Nitrification

“…In soils, monitoring changes in TN, TC, C:N ratios, NH x , and NO x may help infer N 2 O production mechanisms. However, feedyard manure is complex and heterogeneous, contains nonlimiting amounts of C and N, and has variable aerobic and anaerobic microsites (e.g., near water troughs and lounging areas, deep in the manure pack) [4,5,9,43]. As manure changes with wetting and drying, there is potential for simultaneous or coupled N 2 O production from both denitrification and nitrification [8,11,43].…”

“…Beef cattle feedyards produce nitrous oxide (N 2 O) from manure [1][2][3][4][5][6]. Nitrous oxide is a potent greenhouse gas (GHG) implicated in climate change due to a global warming potential (GWP) of 265-298 carbon dioxide equivalent (CO 2 e).…”

“…Approximately 25% of total GHG (N 2 O and methane (CH 4 )) from beef production originates from manure in animal pens and housing [7]. However, few studies sediments, and other substrates are nitrification and denitrification [5,8]. Nitrification and denitrification generally occur under differing conditions (i.e., redox status, available substrates, and microbial community structure and activity) but can occur simultaneously or in tandem in complex ecosystems.…”

“…Feedyard N 2 O emissions are highly variable over both space and time [4,5]. This variability has been linked to temperature [2,4,9], H 2 O content [2][3][4]10], and manure characteristics [1,4,[11][12][13].…”