Soil steaming can prevent the spread of alien species
At SoilSteam, our passion for soil and its soil health is evident through our dedicated team. In addition to our engineering team, we have two dedicated professionals solely devoted to advancing soil health.
Moreover, we foster strong collaborations with academic institutions and researchers worldwide to comprehensively explore and document the impact of steam treatment on soil, encompassing both short-term and long-term effects.
In 2018, SoilSteam started a research project with the Norwegian Institute for Bioeconomic Research (NIBIO) to study how steaming soil can combat alien plant species in contaminated soil masses. The study, “BIOIMMIGRANTS” (https://www.nibio.no/prosjekter/bioimmigrants), which ended in November 2022, resulted in two scientific articles on the topic of soil steaming.
The first paper, Stationary soil steaming to combat invasive plant species for soil relocation (https://www.cambridge.org/core/journals/invasive-plant-science-and-management/article/stationary-soil-steaming-to-combat-invasive-plant-species-for-soil-relocation/822BBCF63526306F7110F5C3A4DE22B1)(Bitarafan et al., 2021), looked at the effect of temperature and duration of steaming on five species.
- Bigleaf lupine (Lupinus polyphyllus)
- Himalayan balsam (Impatiens glandulifera)
- Common wild oat (Avena fatua)
- Canada goldenrod (Solidago canadensis)
- Bohemian knotweed (Faloppia x bohemica)
They concluded that steam is very effective when used to kill the test species and that soil disinfection with steam can prevent the spread of alien species when moving soil.
The second paper, Soil steaming to disinfect barnyardgrass-infested soils (https://www.cambridge.org/core/journals/weed-technology/article/soil-steaming-to-disinfect-barnyardgrassinfested-soil-masses/70CFBC8D3490E42ECD6700C2F8A108A8)(Bitarafan et al., 2021) deals with the different temperatures and exposure time needed to kill barnyardgrass (Echinochloa crus-galli), an extremely harmful species. It concludes that “steaming of soil can guarantee very good control of garden grass seeds in infected soil masses”.
Investigating effect of steam temperature and exposure time on 15 species
Collaboration with academia as well as our own research is an integral part of what we do in SoilSteam. In 2019, SoilSteam received funding from the Research Council of Norway for a project to find the optimal combination of temperature and time needed for steaming to kill various harmful organisms and alien invasive species. The project, which will last until 2025, is called ResourceReturn (link til Forskningsrådets side). The project’s partners are NIBIO, the Norwegian University of Environmental and Biosciences (NMBU), Lindum AS, Toten Onionpackery, Larvik Onion, Norwegian Agricultural Advisory Service, and the National Road Administration.
This project investigates the effect of steam temperature and exposure time on 15 species:
- Common wild oat
- Barnyard grass
- Giant hogweed
- Persian hogweed
- Himalayan balsam
- Scotch laburnum
- Common laburnum
- Garden lupine
- Japanese rose
- Red elderberry
- Black nightshade
- Canadian goldenrod
- Sycamore maple
- Lady’s mantle
- Dwarf serviceberry
Botanical names: Avena fatua, Echinochloa crus-galli, Heracleum mantegazzianum, Heracleum persicum, Impatiens glandulifera, Laburnum alpinum, Laburnum anagyroides, Lupinus polyphyllus, Rosa rugosa, Sambucus racemosa, Solanum nigrum, Solidago canadensis.
NIBIO will publish several reports on the findings of this project this year. So far, we can conclude that steam treatment kills all root parts and seeds of the alien invasive species tested in the project. It’s just a matter of finding the best temperatures and exposure times. We have already gained good knowledge and certainty about the minimum duration and temperatures necessary to combat the most invasive species.
Biodiversity returns
Researchers have shown that biodiversity returns very quickly to the steamed soil, similar to what is seen in the soil after a forest fire. However, other researchers indicate that it takes time for biodiversity to return and question the long-term effects on soil life. What we do know, is that soil steaming has been done repeatedly for more than 100 years, providing healthy and good growth conditions year after year.
In July 2023, a study looking into the effect of steaming fields with the strawberry disease, Red steel (Phytophtora fragariae), in cooperation with the University of South-Eastern Norway (USN) and Bionèr was started. Through this project, we are not only investigating the effect of steam on the pathogen but also analyzing its effect on the soil ecosystems in different soil depths over time.
If we consider precision steaming, a key feature of FieldSaver, potential side effects can be looked at with less concern, as most of the soil is left undisturbed. The soil from SoilSaver will typically be mixed with untreated soil, and natural soil life providing a weed- and pest-free medium for optimum plant health will quickly be established.
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