Mushroom cultivation on substrates with addition of anaerobically digested food waste

Cultivation of mushrooms is an important biotechnological process which converts a wide range of agro-industrial residues into mushroom growing substrates and produces healthy food. Conventional cultivation of Agaricus spp. is performed in composted straw, with chicken manure as the main source of nitrogen triggering the composting process. Anaerobically digested organic waste, i.e. food waste, is comprised of fibrous waste residues and anaerobic bacteria, high in nutrients. The digestate is a rich source of nitrogen, with high pH (8.2) which is favorable for mushroom substrate preparation. Recent focus on renewable energy production has increased the interest in anaerobic digestion - recovering energy, rendering nutrients available for use in agriculture, which makes digestate an easily accessible waste material. The objective of this work was to evaluate usefulness of digestate as a high nitrogen supplement for mushroom cultivation, and waste paper as a carbon source. Yield of three species were compared: Agaricus arvensis, A. bitorquis and A. subrufescens. Mushrooms were cultivated on substrates with increasing amounts of dewatered digestate, ranging from 0 to 40% (DW/DW), with intervals of 10%. For the control, commercial compost was used. Dewatered digestate was added at the start of phase I composting. Substrate preparation was performed according to Stoknes et al. (2013). Results of the present study suggest composted Straw-Paper-Digestate substrate can be used for mushroom cultivation of investigated species compared to control compost.