Integrating intensive mushroom and vegetable production with a closed-loop indoor growing system

Commodities

Practices

During an age of climate crisis our societies need for adaptation of energy efficiency and resource allocation is paramount. Modern agriculture contributes almost 20% of global Greenhouse emissions (Ritchie, 2020). Both the current mushroom cultivation system and indoor plant cultivation systems have a large efficiency deficit due to their unnatural mono crop cultivation, common with many of today's industries. 

In an intensive indoor plant grow high levels of O2(oxygen) are common due to high rates of photosynthesis, slowing the plant's ability to grow. This is commonly offset by injecting bottled CO2 (carbon-dioxide) to balance desired gas concentrations ensuring ample plant growth. This is not sustainable due to the required shipping and generation of concentrated CO2 bottles. 

In the mushroom fruiting chambers high CO2 concentrations are common due to high rates of cellular respiration. This is very problematic for proper mushroom formation. In mushroom fruiting chambers the excess of CO2 and depletion of O2 is most commonly dealt with by having high exhaust and intake rates. This process poses a huge energy draw due to having to recondition incoming air to ideal temperature and humidity levels.

All trials in this research project will be conducted using a standard 2’x4’x6’ mushroom fruiting tent, and a standard 2’x4’x6’ indoor plant growing tent. The time frame of the crops used in each tent in combination with research project period will allow for multiple replications and variations of a few basic trails. For trial one the two tents will be isolated systems, for all following trials the two tents will be connected by 2 4” vent tubes. Each pipe then is an intake end for one system and an exhaust end to the other system. With two pipes then giving each system individual system an intake and an exhaust. Creating a closed loop between the two systems.   A variable speed 196cfm inline 4” fan will be installed to push air from the plant chamber into the humidification system for the mushroom chamber and then into the mushroom chamber.

Oyster blocks will be roughly 11lb blocks that are composed of 1:1 ratio of Hard wood fuel pellets and Soy bean Hull pellets hydrated to ideal moisture content. These production  blocks will be super pastuerized using proven methods and equipment already on farm. They will then be inoculated with consistent rates of oat spawn. 

Lettuce will be grown in cell trays in an on farm compost blended media. 

  Planting and harvest of produce will be timed to optimize quality of produce and hone in on optimizing systems efficiencies.

1)  Trial - baseline

- Mushroom tent - 5 blocks oysters

-Plant tent - 6 trays lettuce

-Ventilation - none

-Monitor - CO2 ppm, O2 ppm, temperature ( F), Relative humidity (%), photos

-Time frame - day 1- estimated 60 (days)

2) Trial - 1 on 20 off 

-Mushroom tent- 5 blocks oyster

-Plant tent - 6 trays lettuce

-Ventilation - 196cfm fan 1 minutes every 20 minutes

-Monitor - CO2 ppm, O2 ppm, temperature ( F), Relative humidity (%), photos

-Time frame - day 65- estimated 125 (days)

3) trial - adjust timing to balance towards equilibrium for both chambers, based on trial 2 

-Mushroom tent- 9 blocks oyster

-Plant tent - 12 trays lettuce

-Ventilation - 196cfm for adjusted rate

-Monitor - CO2 ppm, O2 ppm, temperature ( F), Relative humidity (%), photos

-Time frame - day 130- estimated 190 (days)

4) trial - adjust tray and block count based on previous trials to optimize production of both 

-Mushroom tent- adjust number of blocks oyster

-Plant tent - adjusted number of  trays lettuce

-Ventilation - 196cfm fan 1 minutes every 20 minutes

-Monitor - CO2 ppm, O2 ppm, temperature ( F), Relative humidity (%), photos

Time frame - day 195- estimated 255 (days)

5) following trials will be replicates, or continued variations depending on what data is showing needs further testing.

Objectives

1. Implement and evaluate the real world combination of research previously done separately for mushroom fruiting chambers and indoor vegetable production into a single closed loop system.
2. Identify a balance of tray to block ratio that maintains ideal plant and mushroom growing parameters in a closed system. 
3. Share findings through a mushroom cultivation workshops
4. Based on results, continue to further evaluate and refine the system.