Is a vineyard able to offset GHG emissions released during the grape production process?

Agriculture plays a double role in affecting the atmospheric greenhouse gases (GHG) emissions. It both emits a large amount of GHG, but it also contributes to sequester carbon. The main goal of this work was to investigate the capability of a Mediterranean mature vineyard in offsetting the GHG emitted during the grape production process. The research tried to identify the agronomic practices that mainly contributed to emissions and to include the vineyard biogenic contribution in the net carbon budget calculation. The Carbon Footprint (CF) analysis was conducted to estimate the direct (CO2) and indirect (Nitrogen emissions converted in CO2-eq) emissions related to soil management, use of fossil fuel, and from activities affecting the short-term carbon cycle (e.g. pruning, harvesting, and human metabolism of workers). In addition, the Eddy Covariance technique was used to directly measure the CO2 exchange over the vineyard. The net CO2 budget of the vineyard was computed by combining the measured fluxes and the GHG emissions estimated by the CF analysis. Results showed that the production of 1 kg of grape determined a total amount of GHG emissions of 0.39 kg CO2-eq mainly from fossil fuel combustion and soil management. Since farmer already reduced the amount of applied fertilizers, this practice does not have a relevant impact in the total GHG emission quantification. The conversion from the current conventional management to organic one will not probably determine a significant improvement. A solution to reduce the global warming impact resulting from the use of agricultural machinery could be found in reducing soil tillage practices and using biodiesel fuel. In addition, results confirmed the capability of the vineyard to offset the CO2 emissions released during the agronomic practices. Plants physiological processes, row cropping, and soil, in fact, contributed to sequester part of the carbon released during the year.