Abstract
BACKGROUND: The integration of conservation tillage and organic material applications presents a promising, sustainable approach to improving soil biological health in organic viticulture systems without relying on synthetic inputs. However, long-term studies evaluating their combined effects on soil microbial biomass and enzyme activities under organic management remain limited. METHODS: This ten-year field study (2012-2021) investigated three tillage systems (conventional, reduced, and no-tillage) combined with four organic material treatments (control, broccoli, Antep radish, and olive mill wastewater) in an organic vineyard. Basal soil respiration, organic carbon content, microbial biomass carbon (MBC) and nitrogen (MBN), and the activities of key soil enzymes (β-glucosidase, alkaline phosphatase, and urease) were measured annually. RESULTS: Basal soil respiration significantly increased (p <0.05) by 50.0%, from 23.8 mg CO₂-C 100 g⁻¹ in 2015 to 35.7 mg CO₂-C 100 g⁻¹ in 2021, with no-tillage systems showing the highest values (34.1 mg CO₂-C 100 g⁻¹). Soil organic carbon content significantly rose from 1.4% in 2015 to 1.7% in 2021 (p < 0.05), reaching 2.0% under olive mill wastewater treatment. Broccoli application resulted in the highest microbial biomass carbon (246.6 µg g⁻¹) and nitrogen (206.9 µg g⁻¹), both significantly higher than the control (p< 0.05). Enzyme activities, particularly β-glucosidase and alkaline phosphatase, were markedly enhanced under no-tillage and organic material treatments (p < 0.05), with alkaline phosphatase activity peaking at 1113.2 µg pNP g⁻¹ 2h⁻¹ under olive mill wastewater treatment. Correlation analysis revealed strong positive relationships between basal soil respiration and urease activity (r = 0.86), and between β-glucosidase and alkaline phosphatase activity (r = 0.95), indicating synergistic improvements in soil biochemical functioning. In contrast, microbial biomass parameters showed weak negative correlations with enzyme activities, indicating potential trade-offs between microbial growth and enzymatic turnover. CONCLUSIONS: No-tillage systems consistently promoted higher microbial activity and organic carbon levels, confirming their long-term benefits for soil health. Combining no-tillage with organic material amendments, particularly broccoli and Antep radish, represents an effective strategy to enhance microbial and enzymatic functions critical for nutrient cycling. This integrated approach supports the sustainability of organic vineyards by improving soil biological properties and ecosystem resilience.