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Title: Ecosystem level measurement of methane fluxes over grazed wheat pastures

item Wagle, Pradeep
item Gowda, Prasanna
item Steiner, Jean
item Northup, Brian
item Neel, James
item XIAO, XIANGMING - University Of Oklahoma
item BASARA, JEFF - University Of Oklahoma

Submitted to: Grazinglands Research Laboratory Miscellaneous Publication
Publication Type: Abstract Only
Publication Acceptance Date: 6/26/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Abstract only

Technical Abstract: Methane (CH4) is the second most important human-induced greenhouse gas (GHG) after carbon dioxide (CO2) and accounts for approximately 17% of global anthropogenic radiative forcing. Agriculture accounts for approximately 50% of total anthropogenic emissions of CH4, while enteric CH4 emission from fermentative digestion by ruminant livestock accounts for approximately 33%. It is important to measure CH4 emissions from grazing pastures. The eddy covariance (EC) technique was employed to measure CH4 fluxes from three grazed (graze-out till, graze-out no-till, and graze-grain no-till) winter wheat (Triticum aestivum L.) pastures to quantify the magnitudes and seasonal dynamics of CH4 fluxes for the 2016-2017 wheat growing season. The wheat fields were grazed by mobile cattle. The CH4 fluxes were mostly around 0 umol m-2 s-1 over most diurnal time scales, with some larger spikes (both intake and release). No clear differences in diurnal and seasonal patterns of CH4 fluxes were observed during grazing and non-grazing periods. The results indicate that measuring the contribution of moving cattle on CH4 emissions in large pastures using an EC system in the center of the pastures is a challenging task. High stock rates and relatively small fenced plots or paddocks close to the EC tower could be options for capturing CH4 emissions from moving cattle.