Progress report for FNE23-062
Project Information
This project seeks to analyze the effectiveness of off grid methods of heating and cooling a greenhouse by implementing root zone temperature control through rocket stove technology and Amish ice box techniques. The effects of these methods on the ambient temperature of the greenhouse will be assessed, as well.
Objective 1) Asses rocket mass stove technology and Amish ice box techniques to heat and cool plant root zones and ambient temperature effects from thermal mass temperature regulation.
Discovery: The rocket mass stove and Amish ice box will effectively regulate greenhouse temperatures through thermal mass transfer of radiant heating and cooling. Production will increase through root zone temperature management.
Farmer Impact: This project will provide data on the effectiveness of thermal mass temperature control to regulate ambient air temperatures in a greenhouse. It will serve to assess the efficacy of temperature control of plant root zones and how production is affected. A tool kit will be constructed for other producers to access and will be made available digitally and distributed through online platforms and networking groups.
The problem we seek to address is to regulate temperatures within a greenhouse. It is imperative that the temperature of the greenhouse be regulated in both summer and winter. The stress that is caused to the plants and the workers from the large temperature fluctuations effects production while creating a volatile and dangerous work environment. When temperature fluctuate from 80 to 200 degrees, plants arrest and employees suffer from heat exhaustion. We are proposing to cool the root zone of the plants while thermally banking those cooler temperature within the soil which will slowly radiate into the environment providing ambient temperature regulation. This method has been trialed with success through hydronic systems which can be costly. We are proposing to trial a similar concept of cooling the soil structure but through a more analog approach that would require less expense. The same system will be reversed for heating the root zone in the winter. By integrating both strategies into the same mechanism square footage required for both systems will be greatly reduced translating to more production space. By concentrating efforts of temperature control in the root zone the plants will be less stressed and provide better production. Plants can produce more optimally if their root zone temperature is ideal.
‘Root zone heating is an effective option for greenhouses that provides heat directly to the growing media rather than heating the air of the greenhouse. This approach provides a triple benefit for greenhouse growers: faster production, higher quality crops and energy savings. If the root zone temperature is maintained at the optimum, air temperature in the greenhouse can be lowered 5 to 10 degrees F., reducing heat loss to the outside and therefore, reducing energy consumption. This is possible because root zone temperature is more critical than leaf temperature for achieving good plant growth.’ (Farm Energy, 2019).
‘A healthy plant with a consistently optimal root zone temperature will be indeed more resistant to extreme temperature fluctuations in the canopy area, pest attacks, nutrient deficiency and fertilizer deficiency. If the root zone temperature goes off the optimal range, the plant would experience a reduction in micro-organism and micro-element activity, and would suffer from a lack of nutrients such as nitrogen, phosphorus, as well as micro elements such as iron. Additionally, the growth might be slower or could stop completely, causing poorer yields and quality.’ (MMJDaily, 2020).
We will be implementing a rocket mass heater for winter use and an Amish ice box during the summer months. Both will share a stratification chamber which will be thermally coupled with raised beds on either side of the chamber. This will allow for an easy transition between winter and summer. The ‘fuel’ for both temperature control mechanisms will be generated from the farm. The fuel source for the rocket mass stove will be provided from our forest restoration efforts. The clay for the cob that will be used to build the mechanism and raised beds will be harvested from the land when we dig a pond for irrigation of the orchard in the summer months and we will harvest ice from the pond for the ice box that will be used in the summer. By utilizing ‘fuel’ generated from on farm resources the dependance on utilities will be reduced thereby lowering overhead costs and reducing the carbon footprint by not having dependance on coal fired electricity plants.
Most farms in WV have a great deal of forest land within the farm. This forces farmers to produce on a small intensive scale, diversify their markets and increases the need to leverage resources efficiently. Rural farms are hard to reach and often do not have access to utilities. These methods can all be produced with resources on hand and have an added effect of integrated land management into the resource stream for the system. All systems point back to one another, closing an energy loop.
The impact this method could have to farmers would be enhancement of land stewardship through utilization and management of on farm resources, decrease of outside resources, and provide year round production methods to increase yield and decrease overhead cost which translates to larger profit margin. This would also provide community access to local food year round which provides resiliency to the local food system and reduces greenhouse emissions by lowering food miles in the value chain.
Cooperators
- - Technical Advisor
Research
Objective 1) Asses rocket mass stove technology and Amish ice box techniques to heat and cool plant root zones and ambient temperature effects from thermal mass temperature regulation.
Methodology: A 40 foot thermal mass rocket stove will be constructed. It will be integrated into two 40 foot L x 3 foot H x 2 foot D raised beds constructed of sustainable materials. There will be two beds that share the same internal wall. This internal wall will be the stratification chamber for the rocket stove and the ice box. The rocket stove will be utilized during the winter and the fuel will be provided by forest restoration efforts. The same internal wall will act as the thermal sink for the cooling chamber as well. An Amish ice box will be constructed and during the summer months we will use ice collected from the pond that will be dug to gather the clay for the cob that will be used for the construction of the integrated system. The soil temperature and water retention of the raised beds will be monitored to assess the thermal capacity of the soil and the effects that may have on water retention and plant growth. The plant vigor will be measured in height and yield. The ambient temperature and humidity of the surrounding area will be monitored to assess the effects of the thermal mass at heating and cooling the ambient temperature through radiant release. The results will be compared to the current production method of growing in pots and running fans in the summer and gas heat in the winter, both areas will utilize shade cloth in the summer and supplemental light in the winter. Tomatoes will be the trial plant for both scenarios.
The raised beds and stratification chamber will be constructed of cob by utilizing straw, clay, and sand. The clay will be gathered from the property when we dig a pond for ice collection and irrigation for the orchard. The stratification chamber will serve as a shared wall between two raised beds. The stratification chamber will radiate heat and cool temperatures into the soil’s thermal mass and regulate the temperature of the plant’s root zone. There will be an integrated rocket stove on one end of the stratification chamber and on the opposite end will be an Amish ice box. The system will flip between the rocket stove and the ice box between the season changes. The ice box will act in the same fashion by utilizing the stratification chamber to transfer temperature into the soil mass.
The soil temperature and moisture will be monitored and recorded by using a soil temperature and moisture probe. The surrounding area’s temperature will be monitored by a thermostat and humidistat. Both will be recorded daily. The growth rate of the tomatoes will be measured and documented in inches once a week, along with harvest weights. The same protocols will be followed in the section of the greenhouse where the tomatoes will be grown in pots with gas heat and fans. The results of both production areas will be compared at the end of the trial.
A tool kit will be created from the findings of the trial and made digitally available to other growers. We will hold an open house for producers that prefer to see the test site in person.
Measurement: A decrease/increase in temperature in the summer and winter while increasing plant yield and reduce/eliminate reliance on utilities.
Learning Outcomes
We have been working diligently to build our stratification chamber from cobb. Through trail and error we have learned more efficient processes of construction. We have almost completed our first stratification chamber and can then proceed to building out the rocket stove and wicking raised beds. We have developed a completely new method of construction since the onset of the project and will employ the new technique in the second construction. We are hopeful the new technique will add much need efficiencies to the building process. Even though our current technique is arduously slow it is viable and will be a good resource for someone who lacks funds but has time and/or access to volunteers. Both techniques and finding will be included in the tool kit at the conclusion of the project.
We have also begun construction of the Raspberry Pi for data collection.
