Copper Content and Export in European Vineyard Soils Influenced by Climate and Soil Properties

Copper-based fungicides (Cu_f) are used in European (EU) vineyards to prevent fungal diseases. Soil physicochemical properties locally govern the variation of the total copper content (Cu_t) in EU vineyards. However, variables controlling Cu_t distribution at a larger scale are poorly known. Here, machine learning techniques were used to identify governing variables and to predict the Cu_t distribution in EU vineyards. Precipitation, aridity and soil organic carbon are key variables explaining together 45% of Cu_t distribution across EU vineyards. This underlines the effect of both climate and soil properties on Cu_t distribution. The average net export of Cu at the EU scale is 0.29 kg Cu ha^-1, which is 2 orders of magnitude less than the net accumulation of Cu (24.8 kg Cu ha^-1). Four scenarios of Cu_f application were compared. The current EU regulation with a maximum of 4 kg Cu ha^-1 year^-1 may increase by 2% of the EU vineyard area, exceeding the predicted no-effect concentration (PNEC) in soil in the next 100 years. Overall, our results highlight the vineyard areas requiring specific remediation measures and strategies of Cu_f use to manage a trade-off between pest control and soil and water contamination.