The potential of management residues from heathland and forest as a growing medium constituent and possible peat alternative for containerized ornamentals

To date, the potential of management residues from heathland and forest as a growing medium constituent and a peat alternative have scarcely been studied. Especially sods (plaggen) and chopper have interesting properties, such as low nutrient content and low pH. Three residue types, selected to account for variability in vegetation type and management technique, were characterized chemically and physically and compared to a reference peat-based growing medium. A pot experiment was conducted in 2016 to evaluate plant growth in different peat:residue growing media (60:30, 30:60, 0:100 vol.-%). All growing media complied with the Belgian Federal Legislation (pH-range from 4.5 to 7 and EC<750 µS cm^‑1). Juniperus s. ‘Blue Arrow’, Cornus a. ‘Sibirica’, Hydrangea pan. ‘Pinky Winky’ and Elaeagnus ebbingei were chosen as model plants. Growing media characteristics and plant performance (plant growth and root development) were monitored for four months during the experiment. In general, analysis revealed that the 60:30 vol.-% growing media provided favorable growing conditions for all residue types, showing their potential as peat alternative and as novel and local available growing medium constituents in Belgium. In particular forest sods and heathland chopper are potential peat alternatives, with chopped heath biomass showing the best results. Heathland sods were less performant for plant growth as well as root growth but still provided acceptable results as a peat alternative.