Soil-Steaming and Steam-Boiler Blog

A special source of danger of reinfecting soil with pathogens after steaming is deeper soil. Depending on the root depths of the planted culture, phytopathogenic organisms can reach and contaminate deeper layers of soil. It can happen that steamed higher layers of soil are reinfected by such deep lying pathogens.

Hence when soil is heavily contaminated it is recommended to take soil samples from different soil depths depending on the root depth of the planted crop and check on diseases in order to identify the necessary steaming depth.

Furthermore the injection of beneficial active micro organisms after steaming into the soil can significantly strengthen the resistance against intruding pathogens and immensely inhibit recontamination.

The danger of recontamination on the surface by carry over e.g. when using foreign substrates or planting contaminated plants can be limited through the injection of beneficial microorganisms.

In contrast to other agents (such as air) water has the ability due to its high specific heat to absorb a tremendous amount of energy at a constant temperature of 100°C when transforming from water to steam. This energy is released in the soil for disinfection.

As a result this method obtains a particularly high degree of efficiency with which all organic pathogens are killed at sufficient time of exposure.

Due to the relatively low temperatures of just up to 100°C during the condensation process, soil is prevented from damage. In contrast to the usage of dry heat (e.g. hot air) soil can not be burned and its fertility harmed.
Compared to other chemical agents, water vapor has a comprehensive sterilization effect on soil. All organic pathogens are affected by the humid heat and even killed after sufficient exposure.

Chemical agents only partially take effect, since they are focused on single pathogens only. If soil suffers from different diseases a chemical cocktail is necessary which can lead to enormous risks for the health and environment.

The intense cultivation of agricultural crops challenges nature, since it has a negative impact on the biological equilibrium and strongly promotes the spread and growth of organisms harmful to plants. The culture of resistant high-yielding varieties alone does not solve the issue.
Therefore plant protection and pest control is essential in order to ensure high yields and guarantee the food supply of a steadily growing world population.

Thus soil plays a central role. Under extensive use soil is disabled to control pests though its balanced biological activities. In particular in green houses, soil is exposed to many different diseases which leads to an increased occurrence of wither and root sicknesses, nematodes and weeds.
Soil sterilization is a highly effective treatment method in the area of plant protection.
Two different methods are in use at present: The chemical and the physical/thermal treatment of soil.

Chemical compounds for soil sterilization are easy to use and need little time for application.
Modern compounds have a relatively low effect range, only one or a few specific diseases or pests are overridden. Furthermore the application of chemical agents always comes with a long period of rest which is necessary to degrade or flush them out.

In particular if chemical means for soil sterilization are not applied properly harmful residues might stay in the soil and concentrate in plants which have still unknown effects on plants and man.
Besides the risk of resistance formation can not be ruled out when applying chemical agents which can even aggravate the symptoms of a disease.

Due to the uncertainty of bad side effects chemical agents for soil sterilization should only be applied very carefully, in particular when it comes to vegetable foods.