Monitoring of Soil Copper Concentrations in Different Organic Farms over a Three-Year Period in Apulia, South-Eastern Italy

Copper is considered as a cornerstone of grapevine downy mildew and olive fly management in Apulian organic farms in particular and in the Mediterranean area in general. In this work we studied the influence of soil properties, cultural practices, and pest management strategies on copper concentrations and accumulation in organic vineyards and olive groves of Apulia (south-eastern Italy). In 2005, 2006, and 2007 about 70 soil samples were collected from 13 organic olive groves and vineyards at 0-0.2 m and 0.2-0.4 m depths in five Apulian organic farms representing a wide range of soils physicochemical properties. Results of physical and chemical analyses, carried out in 2005 and 2007, highlighted notable differences between soil samples in terms of total carbonate, clay, and organic matter contents, while pH values were very similar. Copper input in 2004, 2005, and 2006 ranged from 7.6 to 46.8 kg/ha. Total copper concentrations, determined in 2005, 2006, and 2007 with ICP-OES, showed a moderate Cu accumulation, higher in the shallow layer than in the subsoil and in vineyards than in olive groves in all the sampled farms and for both sampling layers. Cu accumulation increased with increasing copper-based treatments number and application rates, and also with increasing pHH2O, clay, and organic matter. Copper availability was higher in the shallow layer than in the subsoil and in vineyards than in olive groves especially in 0-0.2 m layer. Results showed that copper has a medium accumulation in Apulian soils, therefore regulations limiting its use (i.e. CR 473/2002) should be rigorously applied and its alternatives use should be encouraged in order to minimize possible long term effects on soils.