Characteristics of Residues from Heathland Restauration and Management: Implications for Their Sustainable Use in Agricultural Soils or Growing Media

Abstract

Heathlands are among the most important semi-natural cultural landscapes in Northwestern Europe. High-intensity management techniques are necessary to restore and maintain their unique flora and fauna, but generate substantial amounts of residues that have no sustainable reuse so far. This research therefore aims at characterizing these residues and at evaluating their potential as soil amendment or growing medium constituent. Residues are primarily characterized based on their origin and on the management technique used to extract them. We evaluated the spatial distribution of the different residue types and assessed if the used typology also reflects the physicochemical characteristics of the extracted product, by cluster analysis. Finally, the characteristics of the residues were compared with industrial standards and legal limits for growing media or soil amendments and to other growing media constituents. Our results show a difference between extraction techniques, where sods (plaggen) from forests and heathlands have higher bulk densities, lower organic matter contents, lower organic compounds and lower biodegradation potential, compared to heathland chopper. Analyses further confirm the potential of the residues as a raw material for growing media or soil amendments. pH and EC values fall within acceptable ranges (< 6 and < 750 mu S/cm) and nutrient contents are low, with beneficial effects on C:N and C:P ratios. Field and pot experiments are now needed to evaluate effects on plant growth.