Organic substrates for soilless strawberry cultivation from derived products: evaluation of peat alternatives available in Trentino

Soilless strawberry cultivation requires a growing medium with specific physicochemical characteristics, particularly porosity and exchange capacity, which determine the hygroscopic and nutritional conditions suitable for plant development. Sphagnum blonde peat of appropriate granulometry has demonstrated these conditions, becoming the preferred material for this cultivation due to its cost-effectiveness and ease of use. In recent years, environmental pressures to reduce the use of slowly renewable natural resources on one hand, and geopolitical issues suggesting increased costs and risks for production and transportation of materials on the other, have accelerated the search for viable alternatives. Simultaneously, these socioeconomic factors have led to the emergence of initiatives aimed at recovering and transforming products or by-products from various sources: domestic, industrial, energy, or agricultural. In Trentino, composting of domestic waste, bio-digestion of livestock effluents, chipping of tree residues for thermal energy use, and chipping of urban green management residues generate large quantities of organic materials with diverse physicochemical characteristics. The intersection of these two economic-ecological trajectories, one internal and one external to the sector, has led to evaluating their potential applications in soilless cultivation systems. This study aims to utilize these materials to reduce peat usage through total or partial substitution, or by reusing peat for multiple production cycles. Different formulations and management methodologies were determined and tested based on preliminary assessments of the physical-hydraulic and chemical-nutritional behaviours of these materials. Initial results suggest the potential use of some of these materials as supplements to peat previously used in a first production cycle. For example, mixing used peat with a minority proportion of digestate, combined with specific fertigation management, has enabled its reuse in a biennial production cycle with overwintering a limitation typically insurmountable due to the drastic structural deterioration of reused peat.