Toadstool Composting

Toadstool Composting

Sustainable Food Systems


Did you know that 50-70% recyclables delivered to our municipal Resource Recovery Facility at the Santa Cruz Dimeo Lane were actually solid waste contaminants, and therefore could not be recycled? This includes an estimated 56,000 lbs of waste from pizza boxes from the UCSC campus. Toadstool composting is an innovative project underway at UCSC to divert food-stained pizza boxes, which are currently treated as solid waste and can contaminate clean cardboard recycling streams. 

The Goal

Seven students alongside seven faculty mentors recognize the potential implications of this problem and came together to form this S-Lab team, in collaboration with IDEASS and the Sustainability Studies Minor. Their aim is to use mushroom spawn to turn food-soiled cardboard and paper waste into compost and ultimately make a positive impact in the face of crippled infrastructure undermining the U.S. recycling industry.  Tolerance of contamination in recycling has diminished radically ever since China put a customs crackdown on U.S. imports. Soiled cardboard - like pizza boxes - are considered contaminants when mixed in with the clean cardboard stockpiles. The good news is that cardboard retains moisture, corrugation allows for air exchange, and as a wood-based product,  cardboard is a familiar substrate that mycelium can colonize.

Preliminary Results

The team is experimenting with different strains but expect oyster mushrooms to be the most adaptable and aggressive. After learning how to cultivate completing a proof-of-concept, the team will work towards understanding requirements to scale and divert the nearly 4 tons of soiled cardboard discarded on the UCSC campus each month. The resulting compost will rejuvenate soil, increase water holding capacity, and use the land as an effective carbon sink.