Impact of grazing on carbon balance of an intensively grazed grassland in Belgium

Poster (2013, April 09)

This work analyzes the impact of grazing on the carbon balance of a grassland grazed by the Belgian Blue breed of cattle. The research was run at the Dorinne terrestrial observatory (DTO). The ... [more ▼]

This work analyzes the impact of grazing on the carbon balance of a grassland grazed by the Belgian Blue breed of cattle. The research was run at the Dorinne terrestrial observatory (DTO). The experimental site is a permanent grassland of ca. 4.2 ha located in the Belgian Condroz (50° 18’ 44’’ N; 4° 58’ 07’’ E; 248 m asl.). Other studies are conducted at the DTO including measurements of methane (CH4) and nitrous oxide fluxes (Dumortier et al., Geophysical Research Abstracts, Vol. 15, EGU2013-2083-1, 2013; Beekkerk van Ruth et al., Geophysical Research Abstracts, Vol. 15, EGU2013-3211, 2013, respectively). Grassland carbon budget (Net Biome Productivity, NBP) was calculated from Net Ecosystem Exchange (NEE) measured by eddy covariance by taking imports and exports of organic C and losses of carbon as CH4 into account (Soussana et al., 2010). After 2 years of measurements (May 2010 - May 2012), the grassland behaved on average as a CO2 source (NEE = 73 ±31 g C m-2 y-1). After inclusion of all the C inputs and outputs the site was closed to equilibrium (NBP = 23 ±34 g C m-2 y-1). To analyze the impact of grazing on CO2 fluxes, we studied the temporal evolution of gross maximal photosynthetic capacity GPPmax and dark respiration Rd (deduced from the response of daytime fluxes to radiation over 5-day windows). We calculated GPPmax and Rd variation between the end and the beginning of grazing or non-grazing periods (∆GPPmax and ∆Rd, respectively). We observed a significant decrease of GPPmax during grazing periods and measured a ∆GPPmax dependence on the average stocking rate. This allows us to quantify the assimilation reduction due to grass consumption by cattle. On the contrary, no Rd decrease was observed during grazing periods. Moreover, we found that cumulated monthly NEE increased significantly with the average stocking rate. In addition, a confinement experiment was carried out in order to analyze livestock contribution to Total Ecosystem Respiration. Each experiment extended over two days: the first day, cattle was confined in the footprint of the eddy covariance set-up (1.76 ha, 27 LU ha-1) and the second day, it was removed from it. We compared filtered half-hourly data made at 24h intervals, in the presence or absence of cattle, considering that environmental conditions were equivalent (air temperature, wind speed, radiation and wind direction). Results showed that CO2 fluxes were significantly higher when cattle were on the plot. Livestock contribution estimation to CO2 fluxes was on average 6.6 µmol m-2 s-1. [less ▲]

Gestion durable de l'azote au-delà de la seule problématique "nitrate"

in Vandenberghe, Christophe; Colinet, Gilles; Destain, Jean-Pierre (Eds.) et al 2ème Atelier Nitrate - Eau. Evaluation du Programme de Gestion Durable de l'Azote (2013)

The aim of the sustainable management of nitrogen is to reduce dramatically the risk of nitrogen leaching into groundwater. Regulations and recommendations have resulted in a more judicious use of manure ... [more ▼]

The aim of the sustainable management of nitrogen is to reduce dramatically the risk of nitrogen leaching into groundwater. Regulations and recommendations have resulted in a more judicious use of manure as a mineral fertilizer to benefit both the environment and farmers. Rehabilitating leguminous plants into our rotations and our forage areas needs to become a priority. These plants can partially substitute for imported soya and, at the same time, synthesize the free nitrogen available to plants. Management of intercropping and in particular of catch crops can no longer be limited to the single issue of nitrate in water. Integrated crop protection and risk reduction of greenhouse gas emissions also need to be taken into account and flexibility needs to be incorporated into the implementation of these intercropping rules. [less ▲]

3. Contrôle des populations de mauvaises herbes

in Bodson, Bernard; Destain, Jean-Pierre (Eds.) Livre Blanc - Céréales (2013, February 27)

10. Environnement et gaz à effet de serre

in Bodson, Bernard; Destain, Jean-Pierre (Eds.) Livre Blanc - Céréales (2013, February 27)

5. Les régulateurs de croissance

in Bodson, Bernard; Destain, Jean-Pierre (Eds.) Livre Blanc - Céréales (2013, February 27)

Livre Blanc Céréales

Book published by Gembloux Agro-Bio Tech - Edition février 2013 (2013)

Long term measurements of volatile organic compounds exchanges above a maize field at Lonzee (Belgium)

in Communications in Agricultural and Applied Biological Sciences (2013, February), 78(1), 127-132

VOC (volatile organic compounds) include a wide set of molecules which are mostly emitted by the plants. Atmospheric scientists are strongly interested in these compounds because of their important role ... [more ▼]

VOC (volatile organic compounds) include a wide set of molecules which are mostly emitted by the plants. Atmospheric scientists are strongly interested in these compounds because of their important role in the atmospheric chemistry and their final impact on air pollution and climate change. Evaluation of current and future VOC emissions is thus necessary and requires a comprehensive understanding of VOC production and exchange dynamics under a wide panel of climatic conditions and ecosystems. Forest and non pastured grasslands have been largely studied for the last decade. However, knowledge about VOC fluxes from croplands remains scarce. Our study focuses on the VOC exchanges between a maize field and the atmosphere. It is incorporated in a wider project that aims to study VOC fluxes from two croplands (maize and winter wheat) and a pastured grassland. VOC fluxes have been measured on a maize field during the whole growing season using a micrometeorological method (eddy covariance). While first results show half-hourly bidirectionnal exchanges among all the preselected compounds, in average methanol stands for the greatest emitted VOC, followed by green leaf volatiles, and acetic acid is the greatest taken up VOC. Small isoprene and monoterpenes fluxes are also observed. A diurnal pattern is found for all those VOC, with greater emission/uptake during the day, suggesting a flux dependence on environmental parameters. These environmental controls will be further investigated [less ▲]

Stockage de carbone et flux de gaz à effet de serre en prairie (synthèse bibliographique)

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2013), 17(1), 103-117

Grassland carbon (C) sequestration can play an important role in mitigating total greenhouse gas (GHG) emissions of livestock production systems. An accurate inventory of livestock production system ... [more ▼]

Grassland carbon (C) sequestration can play an important role in mitigating total greenhouse gas (GHG) emissions of livestock production systems. An accurate inventory of livestock production system contribution to GHG emissions requires to think in terms of global budget, by considering both the GHG sources and the mitigation potential trough grassland soil carbon sequestration. There is a huge variability in C and GHG balances of grasslands that is mainly due to management practices and climatic conditions. The present article shows that, to reduce the uncertainties of the results, long term measurements at the field scale are necessary. Also, it shows the importance of taking the fluxes of the three main GHGs (carbon dioxide, nitrous oxide, methane) into account when calculating the GHG budget. This article also highlights the need for a better understanding of the mechanisms driving the fluxes, in relation to environmental factors and management practices, in order to propose mitigation strategies able to enhance soil carbon sequestration in soils and to reduce methane and nitrous oxide emissions. [less ▲]

4. Froment: premiers résultats de la récolte 2012

in Destain, Jean-Pierre; Bodson, Bernard (Eds.) Livre Blanc - Céréales - Gembloux (2012, September 06)

2. Variétés - 1. Froment d'hiver

in Destain, Jean-Pierre; Bodson, Bernard (Eds.) Livre Blanc - Céréales - Gembloux (2012, September 06)