Growing southern highbush blueberries (SHB, Vaccinium corymbosum interspecific hybrids) in Florida’s sandy soils presents significant challenges due to their low water retention and limited fertility. Milled pine bark is a widely used soil amendment for SHB cultivation, as it enhances moisture retention, nutrient-holding capacity, soil structure, and maintains an optimal pH (approximately 4.0–5.0) for the crop. However, the physical and chemical characteristics of pine bark, particularly its decomposition dynamics within the SHB rhizosphere, remain poorly understood. This study investigates how pine bark decomposition affects SHB plant growth and productivity. SHB cultivars ‘Optimus’ and ‘Farthing’ were grown in raised beds amended with either aged or fresh pine bark. Plants were irrigated and fertigated via a drip system following commercial production practices. Beginning in June 2024, we measured plant volume, vertically projected leaf area, leaf nutrient concentrations, and yield. In addition, soil and pine bark samples were collected and analyzed. Our findings indicate that plants grown in aged pine bark produced greater above-ground biomass and exhibited higher macronutrient concentrations than those grown in fresh pine bark. The carbon-to-nitrogen (C:N) ratio differed between treatments at the start of the experiment, but fresh pine bark has changed more than aged pine bark since the start of the experiment. These results suggest that fresh pine bark may immobilize nutrients in the SHB rhizosphere, limiting plant growth. A deeper understanding of pine bark decomposition in SHB farms will support the development of sustainable fertilization strategies and improve long-term plant health and productivity.
