Stacked Functionality Greenhouse Use for Mushroom Production: Utilizing space under transplant tables to diversify crops and income

Progress report for FNC21-1291

Project Type: Farmer/Rancher
Funds awarded in 2021: $5,491.00
Projected End Date: 01/31/2023
Grant Recipient: University of Michigan Campus Farm
Region: North Central
State: Michigan
Project Coordinator:
Jeremy Moghtader
University of Michigan Campus Farm
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Project Information

Description of operation:

Student Managed Farm at University of Michigan entering our 10th season of production. We are a 10 acre farm with 3 acres in mixed vegetable production for primarily wholesale institutional markets. We have 13,000 sqft of hoop house space and 3000 sqft of heated transplant production space.

Summary:

This project is to evaluate the feasibility of mushroom production as a stacked use function with transplant production in a heated greenhouse, where mushroom production occurs under transplant production tables in space not normally utilized/occupied.  Potential for stacked use or synergistic production systems that more fully utilize fixed assets/resources in small farming operations has the ability to increase the economic and environmental sustainability of such operations by generating more food production and economic activity from existing heated transplant production spaces thereby increasing carbon and capital use efficiency.  The project will evaluate several different mushroom species/strains (Oyster, Wine Cap, and Shiitake) as well as production techniques to evaluate their suitability for use under transplant tables in heated transplant production greenhouses. This analysis will include evaluation of yield, as well as economics of labor, material costs and potential revenues. Results will be shared with area and regional farmers through a field day hosted onsite (or virtually if needed) as well as more widely through an electronic how-to handbook detailing methods, findings, and recommendations.

Project Objectives:
  • Evaluate feasibility of growing mushrooms under transplant production tables in heated greenhouses.
  • Identify which mushroom types and production systems work best in this environment (wine caps mushrooms on straw or wood chips; oyster mushrooms in totems or in logs; shiitake mushrooms in logs).
  • Evaluate potential economic benefits from this stacked/dual use system that utilizes previously un-utilized space to offset greenhouse heating costs, diversify production and increase economic and environmental sustainability.
  • Disseminate findings and recommendation to farmers in our area though field day and further with a digital workbook detailing techniques, findings and recommendations.

Research

Materials and methods:

We will be growing three different types of mushrooms (Wine Caps, Shiitakes, and Oysters) in a heated greenhouse beneath transplant production tables. These varieties were selected because the inoculum are relatively inexpensive, heat tolerant/loving strains exist, are relatively quick to fruit, and have competitive market prices (each at about $5-10/lb). We are growing these three varieties with a total of five different “treatments” with three replicates of each treatment: Treatment 1: shiitakes will be grown only on logs; Treatment 2: oysters in totems; Treatment 3 oysters on logs; Treatment 4 wine caps on chipped invasive (buckthorn) substrate; Treatment 5: wine caps on straw. Please see the attached schematic drawings to visualize these plans.

To communicate our findings to other small, organic diversified vegetable farms, we will create an online guide for stacked functionality mushroom growing under transplant production tables in heated greenhouses, and hold an educational “Field Day” including a research presentation and greenhouse tour for other Washtenaw County and metro-Detroit area farmers looking to diversify their income and production. We will also work with the students at the Campus Farm in charge of social media to share our progress on Instagram at various stages.

The original drawing was to a 1':1' scale

 

Participation Summary
1 Farmers participating in research

Educational & Outreach Activities

1 Tours

Participation Summary:

10 Farmers participated
2 Ag professionals participated
Education/outreach description:

We have not yet completed our outreach activities. We have given 1 tour but we are not done yet with the project or the education. We have plans to support outreach and tours this season.

Learning Outcomes

Lessons Learned:

Though our project is still in the midst of being carried out, we have still learned a lot up to this point. Our first inoculations of mushrooms was in April 2021, based on grant timeline and availability of the funds. This was a month or two later than we had imagined for optimizing the dual use of the greenhouse  for mushrooms and transplant production.   One effect of this delayed timing was that greenhouse temperatures were warmer for the spawn run and by early June the number of transplants covering tables and being watered was greatly reduced as warm season crops were planted into the field.  This later and warmer window subjected the different mushroom treatments to hotter and drier conditions that were less ideal for mycelium growth.  This was particularly true for the oyster mushrooms both in totems and on logs.  We did observe significant initial mycelium growth in wine cap beds on straw and wood chips in June and by August, the totems were showing significant mycelium growth so we removed their plastic coverings. However, those mushrooms ended up aborting their growth we believe do to high temperatures and drying conditions of the greenhouse in August.  During July and August there were still some transplants in  production and staff watering transplants would spray water under the tables daily to try and help increase moisture content.   This turned out to be insufficient for oyster totems and too much water for the wine caps both on straw and on wood chips which seemed after achieving a good mycelium run to rot rather than fruit. In December when we began washing and packing produce in the greenhouse from our hoop houses and cold storage we noticed that the shitake logs started to fruit but only at the bottom of the logs.  We speculated that this was either due to higher moisture levels on the ends touching the wet soil under the table and or that the mycelium runs in the logs may have only been able to colonize the bottom portion of the logs as the top portions may have become to dry under the hot and dry summer greenhouse conditions.   To test to see the mycelium runs had been good in the logs but that insufficient moisture for fruiting was inhibiting logs from fruiting farther up the logs we soaked logs in water for 24-48 hrs to force fruiting.  

This was successful in getting some fruiting along the entire length of the logs but yields were small.   We also decided to re-inoculate the wine cap bed in December and added 3 additional wine cap beds on straw in February and plan to add a 4th in mid March. 

Things we have learned thus far:

  1. Timing is important as it greatly affects temperatures and moisture levels in the greenhouse.  Inoculating logs, totems or wine cap beds should be done in late December or early January and coincide with the start up of greenhouse operations for the season. 
  2. Shade cloth should be used to cover tables when numbers of transplants are insufficient to keep mushroom production areas covered.   This will reduce drying of the wood and or straw. 
  3. If adding supplemental moisture to wine cap beds, careful observation to only add extra water when needed should be taken. 
  4. Inoculated logs should likely be kept in a non-fruiting position during mycelium runs. This means they should be laid on the ground to encourage more uniform moisture content and greater ability to effectively add moisture and then shifted to fruiting positions after soaking.  Having some under table greenhouse space reserved as fruiting space would likely be ideal.
  5. Since soaking/forcing is likely necessary for logs under greenhouse conditions choosing smaller diameter logs in the 4 inch range may be more ideally suited.

 

Our experiment continues, but at this time it seems shiitake logs with warm season strains may be best suited for use in stacked greenhouse production with transplants. Though we remain optimistic that the wine caps will do better this transplant season under better management conditions and started earlier in the growing season.

Project Outcomes

3 New working collaborations
Success stories:

still working on the project 

Recommendations:

Still Working on the Project 

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.