Leached Copper Correlation with Dissolved Organic Carbon in Sloped Vineyard Soil

The solubility and mobility of copper (Cu) in soil is strongly influenced by the presence of dissolved organic carbon (DOC); however, the interactions between Cu and DOC are complex and not yet fully understood. In this study, Cu and DOC concentrations were measured monthly for two years in leachates from self-constructed lysimeters installed at inter- and intra-row vineyard hilltop, backslope, and footslope areas at the SUPREHILL Critical Zone Observatory, Croatia. The aim was to quantify Cu and DOC leaching from the hilltop towards the backslope and the footslope. The assumed strong relationship between Cu and DOC in the leachates was statistically analyzed and explained using chemical equilibrium software. Leachates were analyzed for pH, EC, DOC, Cu, and major ion concentrations. The highest Cu concentrations found in leachates from the intra-row footslope suggested Cu downhill transport. Although not strong, a significant positive correlation between Cu and DOC in footslope leachates confirmed the relevance of Cu complexation by DOC. Speciation confirmed that more than 99.9% of total Cu in leachates was found as a Cu-DOC complex. Data implied the role of soil water flow pathways in explaining Cu downhill transport. Critical timing for applying Cu fungicides at sloped vineyards was highlighted.

Automated summary

The solubility and mobility of copper in soil are strongly influenced by dissolved organic carbon, though the interactions between copper and organic carbon are complex and not fully understood. This study monitored copper and organic carbon concentrations for two years in leachates from constructed lysimeters in vineyard hilltop, backslope, and footslope areas. Statistical analysis and chemical equilibrium software were used to analyze the relationship between copper and organic carbon. The study confirmed the relevance of copper complexation by organic carbon and highlighted the role of soil water flow pathways in copper transport.