Long-term effects of organic management on soil quality: A comparison of vineyard and field crop systems

This study, conducted in Northeast Italy, examined how long-term organic management affected soil characteristics in vineyard compared with field-crop rotation (FCR). The analysis focuses on copper (Cu) accumulation, soil organic carbon (SOC), total Kjeldahl nitrogen (TKN), iron (Fe), exchangeable potassium (Kexc), calcium (Ca), and magnesium (Mg), as well as key anions and cations, including nitrate (NO₃⁻), sulfate (SO₄²⁻), potassium (K⁺), and phosphate (PO₄³⁻) content across the 0–40 cm soil profile. The highest Cu content was observed in the 0–20 cm vineyard layer (380 kg ha⁻¹), followed by the 20–40 cm layer (315 kg ha⁻¹). However, both layers in the FCR system exhibited the lowest values (119 and 131 kg ha⁻¹, in the 0–20 and 20–40 cm layers, respectively). The upper 20 cm of vineyard soil also showed the greatest SOC content (44.1 Mg ha−1), in contrast to the vineyard subsoil and both FCR depths (average 34.1 Mg ha−1). SO₄²⁻ content and distribution in the soil profile differed between systems: vineyard soil displayed the highest content (∼653 kg ha⁻¹ in the 0–40 cm) and surface SO₄²⁻ enrichment, reflecting recurrent sulfur-based disease-control applications, whereas FCR soil accumulated lower SO₄²⁻ (∼27 kg ha⁻¹ in the 0–40 cm) with a significantly higher content (64.4%) in the 20–40 cm layer, likely due to plow-mediated redistribution. The two compared organically managed cropping systems differently shape macro- and micro-nutrient dynamics. The high Cu accumulation in vineyard soil, related to a prolonged application to control fungal disease, likely impacts soil fertility, nutrient availability, and environmental sustainability.