Copper, zinc, lead and cadmium bioavailability and retention in vineyard soils (Rouffach, France): The impact of cultural practices

Abstract Vegetation cover affects soil erosion, organic matter and nutrient contents, water storage in soil and pesticide leaching. In vineyards where copper fungicides are used, grass cover may affect the distribution and transfer in soil depth of Cu. The aims of this study were to assess the bioavailability of trace elements in vineyard soil and to investigate the influence of grass cover on the retention of Cu following long-term application. As in many vineyards where copper fungicides are commonly used, the studied vineyard soils from the Rouffach catchment are Haplic Cambisol Calcaric Siltic and Cambisol Hypereutric Clayic (Endoskeletic) with different textures. The soils are enriched in Cu and Zn on the surface regardless of the soil texture due to the high organic matter (OM) content and preferential Cu binding to OM. However, sandy soils can retain Cu at greater depths because they contain larger amounts of carbonates, to which Cu also binds. Grass cover appears to reduce the Cu content in surface soils due to direct uptake by the aerial organs of plants, such as vine leaves, or by grass roots. Zn is mainly retained in grass roots, whereas Pb and Cd are minimally available to plants. Loamy soils without grass cover but incorporating OM after weed control appear to have enhanced Cu retention by organic matter. Overall, it appears that the Cu distribution in the studied soils is mainly controlled by organic matter content, textural properties and, to a lesser extent, by cultural practices.