Addressing organic viticulture environmental burdens by better understanding interannual impact variations

Summary

Consumer demand and state incentives in certain EU countries are driving the rapid development of organic viticulture. However, compared with conventional viticulture, it has shown higher interannual variability in its environmental impacts. Improved understanding of this variability would help organic winegrowers better address their environmental impacts.This two-part study examined interannual variability of environmental impacts of four vineyards with contrasting pedoclimatic and technical production conditions. First, life cycle assessments were performed on each of these four vineyards for two contrasted years in terms of both climate and pest and disease pressure. Next, for one of these vineyards located in Mediterranean conditions, life cycle assessments were completed on a chronosequence of six consecutive years. Life cycle assessments of organic wine grapes were calculated based on detailed inventories of data from the eight real vineyard situations. Interannual variations were considered to be the deviation between the impact results of two production years. In all the vineyards, diesel combustion was the main impact contributor. For the four vineyards, the impacts that varied most were generally freshwater ecotoxicity, soil ecotoxicity, marine eutrophication, freshwater eutrophication and metal depletion. The intensity/range of interannual variations differed between plots. The main agricultural operations contributing to impact variations were from disease management of climate-related disease pressures. The 6-year chronosequence analysis showed that certain years were very similar in terms of impact results. The impact that varied most was surprisingly terrestrial acidification. The chronosequence analysis brought to light that the choice of active ingredient could be a greater source of impact variations than interannual climatic conditions and disease pressure. This study provides an overview of the hotspots and variability of organic viticulture environmental impacts in contrasted climate years and a climatic chronosequence. The main pathways for environmental performance improvements are (i) reducing fuel consumption by either limiting the number of operations, using more fuel-efficient machines or different energy sources or/and adjusting tractor speed; (ii) reducing the doses and emissions of copper products and choosing the less impacting types of copper; and (iii) limiting nitrogen and heavy metal emissions through the choice of fertiliser type and management.