ROOT ZONE HEATING & CONTROL
BACK TO NATURE GROWING
Root zone heat can provide more uniform temperature control than a heating system used to maintain air temperature in a greenhouse. This results in better germination of seed, faster rooting of cuttings and better plant growth and disease control in potted plants. The system will pay back quickly in fuel savings due to the lower air temperature that can be maintained.
J. Bartok, Agricultural Engineer, University of Connecticut
Soil heating systems are being used as a means of increasing early and off-season production of outdoor and greenhouse crops, suggesting some potentially valuable applications in California nurseries. Since soil heating systems are well adapted for operation with low- and intermediate-temperature water, there is substantial opportunity to use these systems in co-generation schemes with consequent savings in the base price paid for energy. - B. Jenkins, Associate Professor, Department of Agricultural Engineering & R. Sachs, Professor, Department of Environmental Horticulture. University of California, Davis.
Energy savings are a distinct advantage. Simply put, research has shown that root zone temperatures are more critical to plant growth than leaf temperatures. By maintaining an optimum root zone temperature, greenhouse air temperatures can be lowered 15°F. Researchers in California determined that bench-top heating systems used only half the energy required by a perimeter hot water system. - S. Diver, NCAT Agricultural Specialist
While providing the proper air temperature in a greenhouse or controlled environment agriculture system is important, maintaining the optimum root temperature has a bigger impact on the health and production time of a crop. If plants are grown at root temperatures lower than the optimum, the plants grow slower because their metabolism is slower. In the worst case scenario, if freezing temperatures occur then ice crystals could form in the cells resulting in cell leakage and cell disruption. A disruption of the cell membranes affects the function of the roots resulting in less nutrient uptake, which affects crop cycles and yields.
- R. Raudales, University of Connecticut, Department of Plant Science and Landscape Architecture
The benefits of root zone heating to help extend a plant's growing season or increase plant yield have been recognized and employed by gardeners for centuries. In fact, what happens under the surface is far more important than what happens above. Optimizing your plants' living conditions and will make them healthier and more productive, giving you what you want most out of your garden—less work, less worry and better results. - C. Pianta, Maximum Yield
Therefore, using a floor heating system could allow for a reduction of the nighttime air temperature by 5-10°F or more depending on crop requirements, thus reducing the maximum capacity of the overall heating system, as well as energy costs.
- Root Zone Heating Systems for Commercial Greenhouses; A.J. Both, T.O. Manning, D.R. Mears, E. Reiss; Center for Controlled Environment Agriculture, Rutgers University
Neither warm air nor overhead hot water heating systems are able to maintain warm root zone temperatures for many crops without operating the greenhouse at ambient temperatures higher than necessary. Using floor and bench heating systems, the temperature of the microclimate surrounding the plant canopy can generally be maintained at an optimum level, while the ambient air thermostat setting can be reduced. Thus, floor or bench heating can significantly reduce heating costs, - Root Zone Heating Systems for Commercial Greenhouses; A.J. Both, T.O. Manning, D.R. Mears, E. Reiss; Center for Controlled Environment Agriculture, Rutgers University
What are you actually doing when you heat your root zones? The science behind keeping your roots warm and cozy is explained.
Is Root Zone Heating Really Necessary?" Maximum Yield USA - March 2012 | PDF 3.7MB
By heating soil automatically as needed, ThermoSoil increases convective air flow to the roots and creates an environment that promotes stronger, healthier roots that are more resistant to disease and have a more robust metabolic function.
Three concepts have been integrated to develop low-cost greenhouse structures and environmental control systems that require little energy for winter heating relative to classical systems:  the air-inflated double-layer poly-ethylene greenhouse;  movable thermal insulation for greenhouses; and  root-zone heating systems for production greenhouses.
- Department of Bioresource Engineering at Cook College, Rutgers University