Search

Carbon sequestration and greenhouse gas fluxes in grassland. A review. 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 into account 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.

CO2 flux measurement and carbon balance of agricultural crops. The increase of carbon dioxide (CO2) atmospheric concentration, which is a greenhouse gas, put in stress the need of a better understanding of the carbon cycle and its dynamic. In particular, the exchanges between ecosystems and atmosphere are characterized by large uncertainties. Regional networks were set up to study these CO2 fluxes. In Europe, the CarboEurope-IP network studies the exchanges between terrestrial ecosystems and the atmosphere. It includes more than 100 sites of forests, croplands or grasslands. This article presents the project " CO2 flux measurement and carbon balance of agricultural crops " which was developed in this frame. The main aim of this project is to quantify the CO2 flux evolution of Belgian crops and understand its response to biotic and abiotic factors. In order to meet this goal, measurements are carried out at different spatial and temporal scales. Net ecosystem exchange measurements are carried out every half-hour at the parcel scale. Soil respiration is measured at the soil plot scale with the same frequency. At the leaf scale, net assimilation measurements are performed once a week. Moreover, plant samplings are carried out to determine the crop carbon content. After presenting the objectives of the project, this paper presents the measurement techniques and the fluxes they allow obtaining. The procedures used to combine the measurements in order to assess a complete crop carbon balance are also detailed.