Recycling of Agro-food Wastes into Vineyards by Composting: Agronomic Validation in Field Conditions

Abstract

The objective of this work was to study the agronomic effects produced by the application of agro-food composts in vineyards (Vitis vinifera L.) in organic farming field conditions. To carry out this objective, yield, nutrient contents and quality of fruit, and different physicochemical, chemical, and biological properties of the soil at the beginning and end of the experiment were studied. Four agro-food-derived composts were used. Three of these composts were elaborated mainly using exhausted grape marc and wastes from citrus juice production (C1 and C2) or cattle manure (C3). Compost (C4) was elaborated using the solid fraction of a digestate obtained after the anaerobic digestion of cattle slurry, mixed with vine shoot pruning. Three treatments were used as control treatments: sheep manure (SM), commercial pelletized sheep-derived compost (CC pellet), and a treatment without any organic amendment (B). The study was developed in Fuente Álamo (Albacete, Spain) using Petit Verdot vine variety and organic farming management. The addition into the vineyard soil of the agro-food-derived composts increased soil salinity, the contents in nitrogen and oxidizable organic carbon, and the soil biological activity. Grape yield was also significantly increased with the compost-based treatments compared to control treatment (B), with C1 and C3 showing similar results to the treatment CC pellet. In general, organic amendments did not affect the alcohol production capacity of the fruit but increased the total acidity and the contents of several nutrients, as well as reduced polyphenol levels in grape.