Bio-based fertilisers from fruit and vegetable residues for improving soil fertility and vine status in degraded vineyards

Abstract

The H2020 RUSTICA project aims to propose, demonstrate, and implement technical solutions to convert organic residues from fruit and vegetables into high-quality novel bio-based fertilisers (BBF). These fertilisers address the needs of modern agriculture and close the nutrient cycles on a regional level, fostering a circular economy and promoting sustainability.

Bio-based fertilisers applied individually to the soil are effective in meeting specific functions, however their potential can be fully exploited utilizing them in blends, which leads to fertilisers with multiple functionalities, mitigates negative side effects of blend components, and enables the creation of fertilising products tailored to specific crops and pedoclimatic regions. Furthermore, blending associated with integration of fertiliser manufacturing processes reduces cost and environmental negative impacts of fertilisers production.

In viticulture, BBF blends represent an effective tool for improving vineyards on degraded soils, as they can enhance the quality of the soil and the homogeneity in the vegetative status of vines, while providing environmental services such as climate change mitigation.

This study evaluates three blends prepared with different proportions of BBF, such as microbial protein, insect biomass, insect frass, compost and biochar. Blends’ impact on soil quality and vine status was compared against a control (no fertilization) and two reference treatments (manure and organo-mineral fertiliser) in a degraded vineyard located in the eastern hilly area of Friuli Venezia Giulia region (Italy).

Results of the trial showed that the application of RUSTICA blends had a positive effect on soil and crop traits such as:

• significant enhancement of soil properties (organic C content, N availability, soil microbial pool size and activity)
• improvement of cluster compactness and berry size
• plant productivity comparable to that of organo-mineral fertiliser
• clear effect on the must chemical properties (total N, acidity, pH and soluble solids), with values of maturation indexes within or close to the optimal ranges

Results show that BBF blends represent an effective and viable alternative to usual fertilisers in terms of vine productivity, while improving soil ecosystem functions and grapevine quality in degraded soils. Since they are produced from the upcycling of fruit and vegetable residues, their use in the vineyards can significatively contribute to the sustainability of the wine production.