The GES-Prairie (Greenhouse gases – Grasslands) project has two major objectives:

a) To determine the quantitative balance of net emissions of greenhouse gases in grazed pasture land. Coordinated recordings will be carried out in grasslands grazed by dairy or nursing cattle herds, at the scale of several hectares over several years:

• Continuous monitoring of CO2 fluxes using the turbulent correlations method;
• Measurement of methane emissions by the grazing cattle;
• Intermittent measurement campaigns of N2O fluxes using the turbulent correlations method completed by the regular monitoring of N2O fluxes at the scale of the square metre. The recordings are considered at two sites, both on INRA experimental farms (Laqueuille, in the Puy-de-Dôme, and Mirecourt, in the Vosges).

b) To provide a preliminary estimate of the range of net emissions of greenhouse gases on several typical livestock farms and discuss possibilities of reducing these emissions. Data concerning grazed pastures and knowledge gained in the course of previous programmes will be used jointly to assess the net emissions balance of greenhouse gases on the different types of livestock farms of the studied sites in order to discuss ways of adapting livestock farming systems and pasture management to reduce net emissions (CH4, N2O) or increase capture (CO2) of greenhouse gases.

Expected outputs include the creation of a database collecting all the gas flux data recorded on both sites, and quantified scenarios of greenhouse gas emissions reduction at the scale of the livestock farm.