Soil Management Drives Copper and Zinc Export in Runoff from Vineyard Plots

Copper (Cu)- and zinc (Zn)-based formulations are used globally in vineyards for fungicide protection. Both soil management and rainfall characteristics control the exports of Cu and Zn in runoff from vineyard plots. However, quantitative field studies investigating the influence of soil management on the dissolved and solid-bound exports of Cu and Zn are mostly lacking. Runoff exports of Zn and Cu from northern vineyard plots (Rouffach, Alsace) under conventional (chemical) and alternative (mechanical) soil management practices were compared during two vine-growing seasons. Our results emphasize that mechanical soil management before intense or long rainfall-runoff events favoured Cu and Zn seasonal mass export. Overall, Cu and Zn runoff from the alternative management plot was lower than that in the conventional management plot since grass cover reduced the runoff coefficients. The seasonal Cu and Zn exports during runoff were related to the historical stocks in the topsoil and ranged from 0.001 to 0.071% in the alternative management plot. However, ploughing on the alternative plot followed by a single intense storm event led to extensive Cu and Zn exports, accounting for more than 95% of the total amount exported during the season. In both plots, Cu and Zn were mainly (< 95%) exported from the vineyard plots in association soil particles. Overall, this study underscores that soil management, including soil disturbance before a storm event, can lead to extensive export of Cu and Zn by runoff from vineyard plots. Graphical Abstract