Organic amendment effectively recovers soil functionality in degraded vineyards

The aim of this study was i) to elucidate the impact of land levelling in vineyards on soil fertility and crop development; and ii) to evaluate the effectiveness of amendments in the recovery of soil functionality and vine status in disturbed soils. A field trial was set up on 2 vineyards located in North East Italy and subjected to land levelling. Four treatments were compared and sampled for 3 years: non-amended undisturbed soil (US); non-amended disturbed soil (DS); disturbed soil amended with vermicompost (VC, 1.5 t C ha(-1) y(-1)); disturbed soil amended with vine shoot compost (VS, 4 t C ha(-1) y(-1)). Land levelling negatively impacted soil fertility. In particular, soil organic matter (SOM) and extractable N were decreased by about 20 and 55%, respectively, which were reflected in significant reduction of crop yield and grape quality. Soil displacement had also a negative impact on root spatial distribution and density. Soil amendment was effective in recovering (VC) or enhancing (VS) soil fertility in disturbed soils, in particular by improving water content, SOM, available N and microbial biomass size and activity. Amendments, particularly VS, caused an increase in grape yield, titratable acidity and total N and a decrease of total soluble solids, although differences were not always statistically significant. Our results showed that soil amendment is an effective management for a prompt recovery of degraded soil in vineyards, but a medium-to long-term application of amendments is needed to significantly enhance crop status and grape quality.