Pennsylvania Flower Growers #221
Steaming is an excellent way to treat greenhouse soil mixes as a part of an overall disease and weed control program. It is used to treat soils in ground beds, raised benches and in batches for later transfer to containers. There are two methods in general use for getting the steam to the soil mass. Both systems are used with the assumption that heating will be achieved by a condensation front moving through the soil. If the steam does not penetrate the entire soil mass, heating will be done by conduction from high temperature to low temperature zones. The Thomas method introduces the steam to the top surface of the soil and relies on a slight pressure developed under a vapor tight cover to force the steam down into the soil. Porous hoses are sometimes used to distribute the steam down the length of a bed under the cover.
Keywords: Thomas method buried per forated pipes Copper-constantan thermocouples Soil conditions Steam movement