Carbon budget of a sugar beet crop

Peer reviewe

Cattle methane fluxes measurement over an intensively grazed grassland using eddy covariance

audience: researcherMethane emissions account for 8% of the EU-15 GHG emissions and livestock generates approximately half of these emissions (European Commission, 2009). Recent technological advances in spectroscopy now permit methane flux measurement using eddy covariance. This method has numerous strengths. It can measure fluxes in situ, continuously and across broad areas. This provides information about meadow and cattle emission behaviour throughout the year and across a broad range of climatic conditions. We will present here a one year monitoring of methane exchange between an intensively grazed meadow and the atmosphere obtained using the eddy-covariance method. Methane fluxes exchanged by a grazed meadow were measured continuously since June 2012 at the Dorinne Terrestrial Observatory (50˚ 18’ 44” N; 4˚ 58’ 07” E; 248 m asl.) in Belgium. The site is an intensively pastured meadow of 4.2 ha managed according to the regional common practices where up to 30 Belgian Blue cows are grazing simultaneously. Flux measurements were made with the eddy covariance technique, using a fast CH4 analyzer (Picarro G2311-f) and a sonic anemometer (Campbell Csat3). Carbon dioxide fluxes and various micro-meteorological and soil variables, biomass growth and stocking rate evolution were also measured at the site. Turbulent fluxes were calculated according to standard eddy covariance computation schemes and were filtered for non-stationarity and for low friction velocity (u*) events. During grazing periods, fluxes are dominated by the enteric fermentation source and average 111 nmol m-2 s-1. They are highly variable, probably due to cow movements in and out the measurement footprint and cow digestion rhythm. Despite this spread, a daily emission rhythm is observed with higher emissions during the afternoon. When fluxes are integrated over large periods, methane emissions were found strongly related to cattle stocking rate with a slope of 7.34±0.78 mol CH4 day-1 LSU-1. Further developments are ongoing in order to improve cattle geo-localization through infra-red cameras and individual home-made GPS devices. The two systems will be compared in terms of cost, efficiency and ease of use. During cow-free periods, the methane flux averages 10.5 nmol m-2 s-1 and is highly variable with some production peaks above 100 nmol m-2 s-1. No relation was found between methane fluxes and soil temperature while a weak negative relation was found between methane fluxes and soil humidity. No soil methane absorption has been observed. European Commission. Fifth National Communication from the European Community Under the UN Framework Convention on Climate Change (UNFCCC). Technical Report - 2009 – 038 (2009)

Modeling soil heterotrophic respiration with an enzyme-based model: first comparison with field data and suggestions of improvements

peer reviewe

Génie des procédés : introduction et fondamentaux

International audienceLe génie des procédés, bien qu'omniprésent tout autour de nous, est pour ainsi dire inconnu du grand public. Le début de ce chapitre s'attache donc à donner quelques définitions et repères historiques à propos de cette jeune science appliquée. Les fondamentaux du génie des procédés sont ensuite présentés : en commençant par la thermodynamique, puis les transferts et enfin la cinétique chimique et la catalyse. La dernière partie du chapitre présente la démarche « système-bilans-performance » pour la conception des procédés par le biais de deux exemples simples. Un encadré présente le tout premier niveau de calcul sur les procédés, à savoir les bilans de matière

Response of autotrophic and heterotrophic respirations to soil temperature, humidity, root development and laboratory measurements

peer reviewe

Nitrous oxide flux measurement with a closed chamber system : data treatment

Nitrous oxide flux estimation from concentration measurements with a closed chamber system. Statistical data treatment to sort between relevant/irrelevant fluxes

Short-term temperature impacts on soil CO2 fluxes: An incubation experiment with agricultural soil samples.

peer reviewe

MEASUREMENT OF CATTLE METHANE EMISSIONS USING THE EDDY-COVARIANCE TECHNIQUE

Methane emissions account for 8% of the EU-15 GHG emissions and livestock generates approximately half of these emissions [1]. Recent technological advances in spectroscopy now permit methane flux measurement using eddy covariance. Methane fluxes exchanged by a pasture were measured continuously since June 2012 at the Dorinne Terrestrial Observatory in Belgium. During grazing periods, fluxes are dominated by enteric fermentation. Methane emissions were found strongly related to cattle stocking rate. When fluxes are integrated over large periods and assuming a random position of cows on the pasture, emission per LSU (Livestock Unit) was found to be 53±3 kg CH4 year-1 LSU-1. Recently, cattle position on the grassland was monitored continuously using GPS devices and combined with a footprint analysis [2] to derive more precisely the CH4 emission per LSU. A first experiment with a stocking rate close to 0.7 LSU ha-1 validated the approach and ended in a mean emission per head of 51±10 kg CH4 year-1 head-1. This approach also allows estimating emissions per head at the hourly scale and therefore opens the possibility of studying the circadian emission cycle and to link emissions to feeding behavior of the animal and feed quality