Greenhouse gas emissions from the grassy outdoor run of organic broilers

Bertrand Méda (1, 2) , Christophe Flechard (2) , Karine Germain (3) , Paul Robin (2) , Christian Walter (2) , Mélynda Hassouna (2)

1 URA - Unité de Recherches Avicoles
2 SAS - Sol Agro et hydrosystème Spatialisation
3 UE EASM - Elevage Alternatif et Santé des Monogastriques

Nitrous oxide (N2O), methane (CH4) and carbondioxide (CO2) fluxes over the grassy outdoor run of organ-ically grown broilers were monitored using static chambersover two production batches in contrasted seasons. MeasuredN2O and CH4fluxes were extremely variable in time andspace for both batches, with fluxes ranging from a small up-take by soil to large emissions peaks, the latter of which al-ways occurred in the chambers located closest to the broilerhouse. In general, fluxes decreased with increasing distanceto the broiler house, demonstrating that the foraging of broil-ers and the amount of excreted nutrients (carbon, nitrogen)largely control the spatial variability of emissions. Spatial in-tegration by kriging methods was carried out to provide rep-resentative fluxes on the outdoor run for each measurementday. Mechanistic relationships between plot-scale estimatesand environmental conditions (soil temperature and watercontent) were calibrated in order to fill gaps between mea-surement days. Flux integration over the year 2010 showedthat around 3±1 kg N2O-N ha−1were emitted on the out-door run, equivalent to 0.9 % of outdoor N excretion andsubstantially lower than the IPCC default emission factor of2 %. By contrast, the outdoor run was found to be a net CH4sink of about−0.56 kg CH4-C ha−1, though this sink com-pensated less than 1.5 % (in CO2equivalents) of N2O emis-sions. The net greenhouse gas (GHG) budget of the outdoorrun is explored, based on measured GHG fluxes and short-term (1.5 yr) variations in soil organic carbon.

Mots clés: nitrous-oxide emission; management intensity; temperate grassland; production system; hen run; soil; methane; N2O; CO2; exchange

Domaines: Sciences du Vivant [q-bio]

Bertrand Méda, Christophe Flechard, Karine Germain, Paul Robin, Christian Walter, et al.. Greenhouse gas emissions from the grassy outdoor run of organic broilers. Biogeosciences, 2012, 9 (4), pp.1493-1508. ⟨10.5194/bg-9-1493-2012⟩. ⟨hal-01209096⟩