Methane and nitrous oxide emissions from dung patches deposited by grazing cattle supplemented with maize grain

LOMBARDI, B.; ALVARADO, P.I.; RICCI, P.; GUZMÁN, S.; GONDA, H.; JULIARENA, P.

ANIMAL FEED SCIENCE AND TECHNOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2021

0377-8401

Feeding management represents an opportunity to improve cattle performance in grazing-based production systems and to mitigate emissions of greenhouse gases (GHG) from livestock production. However, it remains unclear how diet affects GHG emissions from dung patches left by grazing cattle. In this study, we evaluated the impact of supplementing the diet of grazing beef steers with maize grain on methane (CH4) and nitrous oxide (N2O) emissions from dung patches and estimated the corresponding emission factors (EF). Gas fluxes from dung and soil were monitored over 125 days, using the static chamber technique. Dung from supplemented grazing steers produced significantly lower CH4 and higher N2O emissions (1.7 g CH4-C/m2 and 0.4 g N2O-N/m2) than dung from non-supplemented steers (4.0 g CH4-C/m2 and 0.1 g N2O-N/m2). Total GHG emissions from dung were similar between treatments (47.8 and 63.5 ± 5.9 gCO2eq/head/d for supplemented and non-supplemented, respectively), although total GHG emissions tended to be less from dung of supplemented grazing steers. The EF values (0.8 g CH4/kg volatile solids (VS) and 0.09% N2O) obtained in this study were both lower than the default values established by IPCC 2006, but were comparable to those established by IPCC 2019. Thus the 2019 EF values should be used for GHG inventories in the study region (Argentina) until more region-specific values are obtained. Based on local information, this study showed that supplementing the diet of grazing steers tends to reduce dung GHG emissions, but further studies are needed to evaluate the complete implications of dietary supplementation on GHG emissions at farm level