Specialty Crops Research Program/

Annual Report, January 1, 2004–December 31, 2004

This is the first progress report on the study of economic potential of vermicompost as a substitute for peat moss in the casing step in white button mushroom, and the production of oyster mushrooms in substrate formulas based on composted green waste. This is a three-year project conducted and reported by University of California Cooperative Extension of Santa Clara County Agricultural Research Program, and sponsored by the California Integrated Waste Management Board (now known as the California Department of Resources Recycling and Recovery or CalRecycle).

Project Title
Developing technology to grow mushrooms from recycled urban waste, food scraps, and paper waste (vermicompost).

Principal Investigator (s) Maria de la Fuente, UCCE Santa Clara County

Executive Summary

We are conducting two independent experiments. In one we evaluate the agricultural and economic potential of vermicompost as substitute of peat moss in the casing step in white button mushroom (Agaricus bisporus) production. In 2003 we set up and brought to steady operation a three-windrow vermicomposting system. In 2004 we processed approximately 1,388 Kg of mushroom waste and 681 Kg of paper, generating between 2-2.5 cubic yards of vermicompost (estimated wet weight 1000 Kg). In Summer-Fall 2003 we ran a pilot test for vermicompost as casing layer with positive results. With appropriate considerations of the learning experience, we will proceed (Winter 2005) to run an experiment with a series of treatments to test the performance of vermicompost as casing layer. The results of the pilot trial in 2003 were very encouraging as they indicated there is great potential for vermicompost to work as a substitute for peat moss, a costly, non-native, and non-renewable product.

We received a BioSystem 500® automated, self-contained modular vermicomposting unit from City of San Jose, and set it up in Royal Oaks Farm. These units are designed to process waste from cafeterias, where it has been observed that vermicompost may get very wet and slurry. We decided to test the functioning of the built in fan system to optimize the performance of the unit, and prevent over accumulation of moisture in the modules. As we did not have a source of power, we modified the modular vermicomposting unit and power the fan system with solar energy. We noticed an improvement in the composting conditions but concluded the fan system needs further improvement.

The second experiment evaluates the production of oyster mushrooms (Pleurotus spp.) in substrate formulas based on composted green waste. We are testing different ratios of composted wood-overs, yard-trimmings compost, and vermicompost. The performance of Pleurotus ostreatus Amycel 3015®, on the experimental formulas, at two spawning (inoculation) rates, is being compared to that on standard/commercial substrates (based on straw or sawdust). Experiments are on their way at the moment. We have observed good colonization in all experimental units. Growth has been especially vigorous in treatments with higher spawning rates, and the production rates are close to lower than the commercial ones.

To develop this project we are working in close collaboration with: Royal Oaks Mushrooms, Countryside Mushrooms, Browning-Ferris Industries (BFI) Organics Division, Z-Best/Zanker Road Landfill, CalRecycle, City of San Jose Environmental Services Department, and County of Santa Clara Integrated Waste Management Program.


a) Evaluate the agricultural and economic potential of substrate formulas based on vermicompost, composted wood-overs, and other alternative materials in the commercial production of oyster mushroom (Pleurotus spp.).

b) Evaluate the agricultural and economic potential of vermicompost as the casing layer in the production of white button mushrooms (Agaricus bisporus).

c) Determine the economic efficiency of each production method: current best practices (baseline) versus incorporating municipal and other organic inputs.

d) Disseminate the findings through various media: open field days, workshops, publication of scientific and popular articles, conferences, poster presentations, and web sites.

e) Organize workshops and provide educational materials on recycling, composting and vermicomposting for workers at growers’ facilities.

Procedures and Methods Established/Used

Evaluation of vermicompost as the casing layer for white button mushroom (Agaricus bisporus) production.

In 2004, we have concentrated on producing all vermicompost possible to have enough supply to run casing experiments. The on-going vermicompost production is taking place in a small barn (20’x 20’) at Royal Oaks Mushrooms farm in Morgan Hill. Three vermicomposting windrows were built (16’x 3’ x 8″) with wooden plank boundaries in Spring 2003. The surface-dwelling earthworms (Eisenia foetida) in the windrows receive weekly or biweekly feeding that consists of mushroom stump waste from Royal Oaks Farm, and shredded newspaper and office paper. Different ratios of mushroom to shredded paper (treatments) were tested (2:1, 1:1, 0.75:1) in Spring 04, but since June 04 feed was applied at no particular rate. Water was added as needed, to keep shredded newspaper in the windrows moist.

To prepare for harvesting or collection of the vermicompost, feeding is stopped and all the remaining non-composted newspaper is removed. The vermicompost is then piled in mounds to aerate. To separate the earthworms from the vermicompost prior to harvesting we tried several strategies: place bedding and food in the middle or at both ends of the windrows, as a “trap.” We are now testing to split in two the windrows (lengthwise), leaving in one side all the vermicompost material piled to dry, while in the other side we placed moistened paper bedding and mushroom feed. Generally the vermicompost in the windrows is left uncovered for 1-2 weeks to air dry, and to force earthworms to move into the straw or the moistened bedding that serves as harboring. Harvesting consists of sifting all vermicompost through a 0.5-inch sieve. Earthworms and non-composted materials are separated from finished vermicompost. The non-composted materials and the worms (and if possible egg sacs) are returned to the windrows they came from and the vermicompost yield (weight) is recorded. Vermicompost is stored for later use.

During the winter months, the interior walls of the barn are wrapped with plastic sheets to give some shelter to the earthworms from low temperatures.

Vermicompost production using BioSystem 500® unit (by BioSystem Solutions):
This modular unit was placed in the same small barn in Royal Oaks Farm where vermicompost windrows are. The unit is a two-drawer cabinet system, built with very sturdy plastic, and includes a built-in fan/heating system to remove excessive moisture requiring 120 Volts AC to operate. Not having 120 Volts AC available in the barn we proceeded to install a solar-panel system that included one each: Deep cycle 12 Volt DC battery, 15 Watt /1 Amp ICP Solar Panel (used to charge the battery), ICP Charge Controller (used to control the battery charging rate), 400 Watt Power Inverter (to convert the 12 Volts DC to 120 Volts AC) to run the Fan. With this configuration, 18 Watts were consumed with only 15 Watts being supplied by the solar panel, and the battery voltage was dropping below the input requirement of the 400-Watt Power Inverter. We then replaced the 120 Volt AC fan/heating-system with a 12 Volt DC fan (80 MM fan with an equivalent air flow) and eliminated the 400-Watt Power Inverter. It was also incorporated a 7 day battery powered (2 AAA batteries) 4 Amp timer to control fan operation.

The system now has two circuits: 1) From the Solar Panel, to the Charge Controller, to the Deep cycle battery; 2) From the Deep cycle Battery, to the7-day timer, to the12-volt DC fan. The system consumption is now 1.5 Watts with 15 Watts supplied by the solar panel. Battery-voltage is maintained between 13.0 and 14.2 volts DC. The Fan will operate between 7 and 14 volts DC. The 7-day timer has been set to let fan run 6-8 hours a day. The vermicompost drawers were set with shredded paper bedding, earthworms, and mushroom waste in late summer. The weight of all components entering the system is been recorded. First harvest will take place in January 05.

Evaluation of oyster mushroom (Pleurotus ostreatus and P. pulmonarius) production on alternative substrates.

Run 1 tested the performance of Pleurotus ostreatus Amycel 3015®, at 5 percent inoculation rate (w/w fresh weight) on the following substrates: a) 2:1 mixture composted wood-overs and fine yard trimming compost; b) 2:1 mixture composted wood-overs and vermicompost; c) 100 percent composted wood-overs; d) 100 percent fine yard trimming compost.

Run 2 tested the performance of Pleurotus pulmonarius Amycel 3014®, at 5 and 8 percent inoculation rate (w/w fresh weight) on: a) 2:1 mixture composted wood-overs and fine yard trimming compost; b) 3:1 mixture composted wood-overs and fine yard trimmings; c) 100 percent composted wood-overs; versus d) commercial control (standard cotton husk + straw substrate). This run was discarded before harvest started due to misting system malfunctioning.

Run 3 (ongoing) is testing the performance of Pleurotus ostreatus Amycel 3015®, at 5 and 8 percent inoculation rate (w/w fresh weight) on a) 2:1 mixture composted wood-overs and fine yard trimming compost; b) 3:1 mixture composted wood-overs and fine yard trimmings; c) 100 percent composted wood-overs; versus d) commercial control (standard cotton husk + straw substrate).

Run 4 (ongoing) is testing Pleurotus ostreatus 3015®, at 8 percent inoculation rate (w/w fresh weight) on a) 3:1 mixture composted wood-overs and fine yard trimmings; b) commercial control (standard cotton husk + straw substrate); c) Penn State substrate recipe (sawdust + wheat bran + millet grain +cotton meal); d) 3:1 mixture composted wood-overs and Penn State grain mix.

For each run, composted materials are hauled from Z-Best (Hollister) to Royal Oaks farm (Morgan Hill), where substrates are prepared and divided into experimental units (containers) and pasteurized. After pasteurization all experimental units are covered and transported to the growing chambers in Countryside Farm (Gilroy), 5 miles apart. Growing chambers are two trailer-rooms (approx. 7’x 7’x 8’) conditioned with waterproofing, installation of shelving and misting system. Moisture and temperature are monitored in the growing rooms, keeping humidity at 80-90 percent with misting system, and temperature (during Fall/Winter 04-05) from going below 40˚F with Holmes-1500 Watt Utility Heater.

Data collection: We are keeping record of yield according to flush interval occurrence. Through the production cycle we will record number of breaks or flushes, yield per flush, size and weight of fruiting bodies, color, grade, yield per surface unit, biological efficiency and total yield, as well as pictorial record.

Major Activities

Research and outreach of each objective addressed, and integration of all (if applicable).

Research activities were detailed in the previous section. In terms of outreach, we have published description and project updates (Compost in Commercial Mushroom Production Project) and in the newsletter “From the Ground Up-Compost News for Landscape and Agricultural Professionals”. Also through presentations at different workshops and seminars such as: a) PAPA Seminar b) CORF Workshop c) Santa Clara County Farm Bureau Agricultural Workshop d) Santa Clara County Department of Agriculture Private Applicator training for growers. We also held four informal meetings with cooperators.

Significant Observations, Results and/or Impacts

We are steadily producing vermicompost in the three windrows. During this year we were able to produce 2-2.5 cubic yards of fine quality material. We are still below the amount we need to run all our casing experiments, as we require at least 0.2 cubic yards per experimental unit. The waste that has been composted totals: 1388 Kg of mushroom waste and 681 Kg of paper.

In terms of oyster mushroom production, we keep troubleshooting the humidity and temperature conditions in the growing chambers. Preliminary results (Run 1) indicated that average production per experimental unit in a substrate with a 2:1 mixture of composted wood-overs and fine yard trimming compost was 2116 g; 1486 g in a 2:1 mixture of composted wood-overs and vermicompost; 985 g in a 100 percent composted wood-overs substrate; and a total of 485 g were collected from the 100 percent fine yard trimmings compost. We were forced to discard a whole experiment (Run 2) due to malfunctioning of the misting system and contamination of the substrates. The results of Runs 3 and 4 will provide a comparison between composted green waste materials as substrate versus standard or preferred (commercial) substrate mixtures, and with this information we will be able to proceed to study the economical efficiency of each production method (Objective C). We have observed good colonization in all experimental units.

Growth has been especially vigorous in treatments with higher spawning rates, but it is too soon to predict how this will translate into yields.

Problems and Unexpected Issues Encountered

Changes made in the project, time frame analyses of actual research and, outreach vs. anticipated/proposed.

We are finally catching up with vermicompost production, as we had to start from scratch a new vermicompost production system. We are at least 3 months behind in the production of vermicompost. Vermicompost harvesting has required more labor than expected as we need to produce a very clean and homogeneous material, and harvesting is all done by hand (not mechanized). Running our experiments to test vermicompost as casing for white button mushroom production in the growing rooms of Royal Oaks Farm affects their normal operations and possibly productivity. For that reason we will run 3-4 production cycles instead of the 7 cycles proposed. We will be able to report on 2-3 production cycles of oyster mushrooms in experimental substrates. We would greatly benefit from an extension of three months to complete the proposed 4-5 production cycles and to be able to repeat the experiments for more consistent results.

We are looking at alternative places to hold 1-2 field days and we already developed the plan to provide the home-waste management training to the employees in Winter 2005. As a bonus training, we are also providing the UCCE EFNEP 16-hour nutrition education to employees and their spouses.

Narrative Summary of Budget

Budget analyses of expected vs. actual expenditures; expected budget changes and/or activity in future.

Expenses have been kept within the proposed budget. We are subcontracting labor with Royal Oaks and Countryside Mushrooms in the fixed-amount of $5,000 each grower for the period of the research (January 03 to July 05 -or September 05 if extension is approved). We received free of charge or in-kind: all composted materials and their transportation from Z-Best, all spawn for oyster mushrooms production and hardwood sawdust from Amycel-San Juan Bautista. In-kind consulting from: Steve Storelli, CalRecycle; Robert Van Tassel, Royal Oaks Mushrooms; Jim Goetz, Countryside Mushrooms; Michele Young, City of San Jose; Alex Sharpe, Z-Best. Use of paper shredder from: Home Composting Program County of Santa Clara and Santa Clara County Medical Association. UC Master Gardener Volunteer support in all vermicompost operation by Mickey Neff (12-20 hrs per month).

Documentation of Activities

Research and/or outreach (e.g. data, photos, reports, meetings, press articles). May be as attachments or in body of report.

The results included in this report to this date are merely observational (for the evaluation of vermicompost); we have gathered all partial data for harvesting, both vermicompost and yield of oyster mushrooms. Documentation of all phases of the project is being carried with photography, as well as some video recording. Project description and updates are posted on the CalRecycle website.

For more information contact: Compost Use in Agriculture, organics@calrecycle.ca.gov