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

Abstract

Beef feedyards produce nitrous oxide (N2O), a potent greenhouse gas. Limited research has evaluated the processes that produce feedyard N2O, and how rainfall and temperature impact N2O losses. Manure in feedyard pens develops into a complex ecosystem of microbes, extracellular enzymes, feces, and urine, with varying H2O content. This study aimed to improve understanding of feedyard N cycling under differing environmental conditions by incubation of manure in simulated feedyard pens using large chambers under laboratory conditions. We hypothesized that nitrification was the primary source of feedyard N2O, with interactions among temperature, H2O content, and manure properties. Emissions of N2O were monitored with a real–time N2O analyzer. Manure samples were taken at intervals for analyses of physicochemical properties, denitrification enzyme activity (DEA), and nitrification activity (NA). Due to equipment limitations, there was only one chamber per temperature tested. Correlation was poor among N2O emissions and rates of DEA and NA. However, significant relationships were found among key manure characteristics, such as ammonia/ammonium and nitrate/nitrite concentrations, manure dry matter, redox status, and temperature. These data suggest that most N2O was derived from denitrification in the top 5 cm of the manure pack. Further study is warranted to identify the processes involved in flushes of N2O emitted immediately after rainfall, possibly due to abiotic chemical reactions that release N2O sequestered in manure pores.

Microbial community structure from southern High Plains beef cattle feedyard manure and relationship with nitrous oxide emissions

“…(2018) and Waldrip et al. (2020), who investigated N 2 O emissions, manure physicochemical properties, and nitrification (NA) and denitrifier enzyme activities (DEA) in feedyard manure under different temperatures and following simulated rainfall. This report takes these works a step further to investigate how the manure microbiome responded and how specific microbial phyla and gene abundances are related to previously measured variables.…”

“…Analyses of DEA and NA were conducted and reported in Waldrip et al. (2020) based on the methods of Woodbury et al. (2001) and Ayadi et al.…”

“…The manure in beef cattle feedyards is a significant source of nitrous oxide (N 2 O) (Parker, Casey, et al., 2017; Redding et al., 2015; Waldrip et al., 2017, 2020; Woodbury et al., 2018), a potent greenhouse gas (GHG) implicated in climate change due to a global warming potential (GWP) of 265–298 carbon dioxide equivalents (CO 2 e). An estimated 25% of total GHG (N 2 O and methane [CH 4 ]) from beef production originates from animal pens and housing (Costa et al., 2014).…”

“…An estimated 25% of total GHG (N 2 O and methane [CH 4 ]) from beef production originates from animal pens and housing (Costa et al., 2014). Studies have investigated the effects of temperature, rainfall, and activities of enzymes involved in feedyard N 2 O emissions (Ayadi et al., 2015; Waldrip et al., 2020; Woodbury et al., 2001, 2018), but little work has characterized the manure microbiome or presence of specific genes responsible for N 2 O production. In 2011, livestock manure contributed an estimated 4.3–5.8 Tg N 2 O‐N yr −1 globally (Syakila & Kroeze, 2011), which has been gradually and steadily increasing.…”

“…Feedyard N 2 O emissions are highly variable over both space and time (Aguilar et al., 2014; Parker, Casey, et al., 2017; Redding et al., 2015; Waldrip et al., 2016). This variability has been linked to temperature (Parker, Casey, et al., 2017, 2018; Waldrip et al., 2016, 2017, 2020), H 2 O content (Aguilar et al., 2014; Parker, Casey, et al., 2017; Parker, Waldrip, et al., 2017, 2018), and manure characteristics (Ayadi et al., 2015; Liao et al., 2018; Waldrip et al., 2017, 2020; Woodbury et al., 2001). Both air temperature and precipitation range widely in the Texas Panhandle portion of the southern High Plains, where this study was conducted (−102.1, 35.2).…”