Recycling Mushroom Spent Compost

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2007: $8,027.00
Projected End Date: 12/31/2008
Region: Southern
State: Puerto Rico
Principal Investigator:
Reed Hepperly
Hepperly Enterprises


  • Miscellaneous: mushrooms


  • Soil Management: composting

    Proposal summary:

    Currently we have no venue to properly dispose the byproduct resulting from our mushroom production. The byproduct consists of the medium (spent compost) in which the mushroom grew. This medium is made up of degraded cellulose and lignin that during colonization by the mycelia of the fungus is enhanced by the nutrients released that otherwise would have stayed unavailable. As our business grows, if this byproduct is not put to good use we will become a point source contributor to nutrient leaching that could in the long run be detrimental to our water ways. We intend to develop a soil mix for potting or other farming applications based on the mushroom spent compost. This will provide the consumer with a ready to use high quality compost. This added value approach provides the mushroom producer with another revenue stream that also stimulates the recycling of agricultural byproducts. It is interesting to note that the plant material has been recycled twice since they it was used to produce the mushrooms which in turn improves the substrate transforming it into a high quality compost that will provide nutrients to other plants or crops. We will first define nutrient composition and physical properties of the mushroom spent compost. Then develop various formulations combining the spent compost with various amendments to define and select the best mix. The preferred formulations will be then tested against currently available commercial potting soil mix. This test will be conducted by growing three plant species measuring seed germination and seedling height. Our selected potting mix formulation will be sent for laboratory analyses to determine nutrient composition and physical properties profiles.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.