Compost Application in the Vineyard and Its Influence on Soil Characteristics, Vegetative and Productive Behaviour of Grapevine

Research was carried out in two vineyards planted with the variety 'Merlot' in order to evaluate the effect of soil compost addition on soil organic matter and grapevine production and quality. The vineyards were established in Valnogaredo and Zovon, on the Euganean Hills, Italy. Two treatments were compared: application of 5 t/ha of compost versus no compost application. Soil and microbial analyses were performed. SPAD values and leaf chlorophyll content were measured during the growing season. Quantitative and qualitative parameters of vine production were evaluated. The soil of the two vineyards was calcareous and gravelly, with clay texture and alkaline pH. Organic matter content increased after the compost treatment, whereas the other investigated parameters did not change significantly. The organic C content increased in Valnogaredo but not in Zovon. The humification index and microbial biomass increased in both vineyards. In 2007 and 2008 SPAD values in the leaves were higher for the compost treated vines compared with those untreated and strong correlations were found with leaf chlorophyll contents. At harvest, in Valnogaredo in 2007 and 2008, in Zovon in 2008 and 2009, an increase in the yield/vine of bunch and berry weight and volume and qualitative parameters were observed in plants treated with compost. In conclusion, compost application, depending on soil characteristics, can increase soil organic matter and microbial biomass but can also affect vine productivity.