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Mushroom Production and Waste Management

The Issue

California produces more than 10 million tons of grass clippings, tree leaves, limbs and twigs, vegetable cuttings and other organic wastes every year. The Integrated Waste Management Act of 1989 (AB 939) required a 25% diversion of this waste stream from landfills by 1995, and a 50% diversion by 2000. Mushrooms grow and produce effectively on highly lignified and composted material. From 1985 to 1999, mushrooms--mostly white button mushrooms (Agaricus spp.)--were the number one cash crop in Santa Clara County. California produces about 40% of all mushrooms in the United States. Mushroom production worldwide has increased in the last 15 years from about 350,000 tons to about 9.9 million tons.

What Has ANR Done?

The City of San Jose's Environmental Services Department contracted with UCCE to conduct a series of research projects to find new applications for composted waste in Santa Clara County's agricultural industry (For details, see www.urbancompost.com). In 1997, as an ongoing project, UCCE started an environmentally controlled evaluation of three substrate formulas based on municipal yard trimmings, to be used for commercial production of a specialty crop, oyster mushrooms. We studied the response of two species of oyster mushroom (Pleurotus ostreatus and P. pulmonarius) to different production methods as a way to give the growers an opportunity to diversify, capturing existing markets, gourmet stores and other consumers. At the same time, we built several vermicomposting (composting with worms) windrows under a protective shed, to handle and process vegetable and fruit waste from supermarkets. The units, originally located at the UC Bay Area Research and Extension Center, were rebuilt at a mushroom-growing operation in Morgan Hill. The goals are to (1) demonstrate "low-tech" mid- to large-scale vermicomposting as a valid food-waste reduction mechanism, (2) help growers recycle their own agricultural waste (mushroom sumps), (3) provide training in the vermicomposting process and (4) maintain a demonstration site. We also are studying the potential use of vermicompost as a substitute for the peat moss used in the casing layer, a very important step in white button mushroom production.

The Payoff

City of San Jose surpasses proposed state goal!

The City of San Jose diverted 53% of its waste from landfills by the year 2000 and was one of the first large cities to be in compliance with AB 939.

As a result of our small to medium-scale demonstration vermicompost units, children of K-6 age, high school and college (San Jose State University) students, Master Gardeners and Master Composters, public agency representatives and the general public are getting information and training on an exceptionally simple technology for food waste reduction. Two local chefs have adopted, with slight modifications, the proposed technology to dispose of their restaurant food waste.

The mushroom industry in Santa Clara county has increased from $35 million gross value (1996) to $48 million (2004). A considerable shift has occurred in the varieties used for the mushroom supply. White button mushrooms still account for 70% of the market, but oyster mushrooms and shiitake, the main specialty genera, are increasing their shares.


Supporting Unit: Santa Clara County

Maria de la Fuente, Ph.D., County Director and Farm Advisor
UCCE Santa Clara County, 1553 Berger Drive, Bldg. 1, San Jose, CA 95112
(408)282-3131, medelafuente@ucdavis.edu