Do DOM optical parameters improve the prediction of copper availability in vineyard soils?

Area of Science:

• Environmental Chemistry
• Soil Science
• Agricultural Science

Background:

• Copper-based fungicides are crucial in viticulture but can lead to soil copper accumulation.
• Soil properties like pH and dissolved organic matter (DOM) influence copper (Cu) bioavailability and potential toxicity.
• Understanding copper availability is key to ensuring winegrowing sustainability and ecosystem health.

Purpose of the Study:

• To investigate the role of chromophoric and fluorescent dissolved organic matter (DOM) properties in predicting copper availability in organic vineyard soils.
• To assess the contribution of DOM quality indices to copper solubility predictions.
• To evaluate the influence of soil parameters on copper speciation in vineyard soils.

Main Methods:

• Analysis of DOM properties using absorbance and fluorescence spectroscopy.
• Measurement of total soluble copper (Cu_KCl) and free ionic copper (Cu2+) in KCl extracts.
• Development of multilinear regression models incorporating soil pH, total copper, and DOM quality indices.

Main Results:

• Soil pH was the primary predictor of free ionic copper (Cu2+), explaining 88% of the variance.
• Copper solubility (Cu_KCl) was best predicted by a model including pH, total copper (Cu_T), and DOM fluorescence indices (FI and HIX), explaining 83% of the variance.
• While DOC concentrations were similar, DOM quality varied significantly among soils, affecting copper solubility.

Conclusions:

• Soil pH plays a dominant role in determining copper availability in vineyard soils.
• Dissolved organic matter quality, particularly its fluorescence properties, is important for accurately predicting copper solubility.
• Integrating DOM quality parameters into models can enhance our understanding of copper dynamics in agricultural soils, supporting sustainable wine production.