Soil – A Vital, Non-Renewable Resource

The day opened with Vestfold County Mayor, Anne Strømøy, who reminded the audience that soil is one of our most important – yet non-renewable – resources. She announced that the county will now require contractors to recycle soil masses containing invasive species and plant pathogens instead of treating them as waste.

“We cannot continue to treat soil as a waste problem. It must be seen as a resource to be protected and reused,” said Strømøy.

Technology That Changes the Industry

SoilSteam CSO, Hans Kristian Westrum, emphasized that landfilling soil has no place in a modern, sustainable society.

“SoilSteaming is often more affordable than landfilling. The technology removes weeds and plant pathogens while improving soil quality. With three machines already in Norway, one in Sweden, and one in the UK – the solution is here. Now we call on municipalities, consultants, and contractors to make SoilSteaming the standard in construction and road projects.”

The audience also heard from Gjennestad Drift’s Arne-Olav Klevsgård, who shared why his company is now adopting SoilSteaming:

“We’ve long struggled to secure soil of good quality. Now we can guarantee weed-free soil for ourselves and others, while contributing to a more sustainable resource cycle.”

From Theory to Practice

After the presentations, participants witnessed SoilSteam’s machines in action. Two models – SoilSaver 20 and SoilSaver 5 – were demonstrated in the field. Visitors also compared steamed soil with untreated soil, six weeks after treatment. The results were striking:

The steamed soil remained completely weed-free

• Grass grew better in the treated soil than in the untreated sample

“SoilSteaming doesn’t just eliminate weeds and pathogens – it can actually improve the soil’s growth properties,” summarized SoilSteam CEO, Ken Roar Riis.

A Step Toward a Circular Future

The Demo Day made it clear that interest in delivering heat-treated soil in line with the new upcoming standard is growing fast. With support from public authorities, industry leaders, and pioneering companies, SoilSteaming is becoming a key driver for a circular economy in both construction and agriculture.

You can see a summary of the day here

✅ Learn more about SoilSteam and our mission to redefine soil management: www.soilsteam.com

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Soil recovery as an alternative to costly landfilling

Instead of transporting the soil to landfill – which is both expensive and environmentally taxing – the masses were treated directly on site using heat. The SoilSaver technology uses hot water vapor to eliminate biological contaminants, without chemicals, while preserving the soil’s structure and function as a growing medium.

The project was carried out as planned in terms of time and budget. Trafikverket views the technology as a potential way to reduce the high costs associated with current practices:

“This is about finding out whether we can handle the soil on site at a reasonable cost instead of hauling it away and burying it in landfill, which is expensive,” says Claes Dahlgren, national coordinator for invasive species at Trafikverket.

“The landfill cost alone is around 1,500 SEK per ton,” he adds.

– Landfilling costs several times more than treatment

Hans Kristian Westrum from SoilSteam comments:

“We see time and again that recovering soil with our SoilSaver makes projects more sustainable – not only environmentally and ecologically, but also economically.
Our treatment cost is just a few hundred NOK per ton. In this project, the landfill cost alone was several times higher than the treatment cost.

We have to stop landfilling material that is cheap and easy to recover. Landfills should be reserved for waste we cannot recycle – not for valuable resources that can be reused with minimal effort,” Westrum concludes.

Next steps

Trafikverket will follow up the project throughout the summer and fall to assess the results. Key questions include whether the lupins are effectively eliminated – and whether the treated soil remains suitable for grass and plant growth.

SoilSteam looks forward to the outcome and hopes the SoilSaver can become a useful tool in Sweden’s efforts to manage invasive species through circular, cost-effective and environmentally responsible practices.

Read more from Trafikverket here:
New method tested to stop the spread of invasive plants – Trafikverket (in Swedish)

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In June, the very first SoilSaver 20 machine from SoilSteam will be installed at EWG’s facility in Flen. The machine uses steam treatment to eliminate seeds and plant material from problematic species such as Japanese knotweed, lupines, and giant hogweed – plants that have caused serious challenges for both biodiversity and infrastructure.

A Growing Problem – and a Circular Solution

Soil contaminated with invasive species has long been a headache in Sweden. The usual solution has been to send large volumes of earth to landfill – an expensive and unsustainable practice. EWG Recycling aims to change that.

“We’re seeing stricter regulations from authorities to stop the spread of invasive species, and rightly so. But this has also led to large amounts of valuable soil being discarded, simply because the technology to clean it hasn’t been available – until now,” says Max Lindqvist, CEO of EWG Recycling.

Over the next few months, EWG expects to receive around 30,000 cubic meters of contaminated soil – the equivalent of approximately 2,000 truckloads.

“Now we can clean and reuse this resource instead of filling up landfills. It’s a concrete and important step toward a more circular approach to soil and excavation mass handling. Landfilling should be the last resort.”

Norwegian Technology with European Potential

For SoilSteam, this partnership with EWG marks a key entry into the Swedish market.

“We’ve had ongoing dialogue with Swedish authorities and major players like the Swedish Transport Administration. There’s a growing understanding that soil is a valuable resource, and that landfilling only provides temporary control – not a real solution. EWG is a forward-thinking, innovative partner that shares our vision for circular resource use. We’re excited to begin this collaboration in Sweden,” says Hans Kristian Westrum, founder and CSO at SoilSteam.

A Green Shift – One Truckload at a Time

This isn’t just a tech update – it’s a shift in how we think about soil and waste. Instead of treating soil contaminated with invasive plants as a problem to be buried, EWG and SoilSteam see it as an opportunity for value creation and environmental gain.

Sweden now has its first facility for steam-based soil remediation. Will more follow soon?

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Why Hand Pulling Is Ineffective:

1. Deep Root Structure:
   Japanese knotweed has a powerful rhizome network (underground stems) that can grow up to 3 meters deep and spread 7 meters from the parent plant. Removing only the visible parts will result in rapid regrowth from the remaining roots.
2. Spread Through Small Root Fragments:
   Even tiny root fragments (as small as 1 cm) can develop into new plants. Hand pulling can inadvertently lead to further spread if root pieces are left in the soil.
3. Rapid Regrowth:
   The plant grows quickly and can return with renewed vigor after pulling, especially if the roots are not completely removed.

Effective Control Methods:

1. Digging:
   Dig out as much of the root system as possible, being extremely careful to remove all root fragments. This process is non-sustainable and often requires repetition over several seasons.
2. Covering:
   Cover the area with light-blocking materials (e.g., thick tarps or geotextile fabric) for several years. This deprives the plant of sunlight, gradually weakening it over time. Ir might be effective, but VERY time-consuming.
3. Steam Treatment:
   For larger areas, steam treatment can be an effective method. Technologies like SoilSteam can eliminate both roots and seeds in the soil using hot steam. This is quick and effective and the soil might be used after. You need large equipment, so this method is for professional use.
4. Continuous Cutting:
   Frequent cutting (every 2–3 weeks) over several years can gradually weaken the plant. Cut material must be disposed of properly to prevent further spread. This is time-consuming and requires discipline.
5. Chemical Treatment:
   Contact a specialist with the proper authorization to apply herbicides. Such treatments typically require multiple applications per season and ongoing follow-up for several years. Due to their potential environmental impact, many people prefer to avoid chemical herbicides in private gardens. Professional help is needed to ensure correct chemical treatment.

When to Seek Professional Help:

Regardless of the method chosen, it is advisable to consult professional help. SoilSteam offers an immediate solution with just one treatment. However, the challenge is that these are large, complex machines, making them economically and logistically impractical for small-scale areas.

All other methods will require continuous monitoring and repeated treatments over several years to achieve lasting results.

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Based on this, we at SoilSteam contribute to developing a Norwegian Standard for heat-treated soil. This standard will ensure that buyers of soil can be confident that the soil is heat-treated and therefore free of harmful organisms and weeds. Steamed soil is becoming increasingly popular among landscapers, and here we explain why:

One of the biggest challenges for landscape gardeners is weeds that compete with plants, creating extra costs and additional work. By using steam-treated soil, this problem is largely avoided. It also reduces the need for chemical pesticides. In addition, the use of steam-treated soil leads to more satisfied customers.

Weeds grow quickly and controlling it throughout the season requires regular maintenance, including weeding at least once a month. In a hectic summer season, this can be difficult to achieve in practice, which often results in planting areas that look poorly maintained. By using steam-treated soil, this problem is avoided. The soil will generally remain weed-free without incurring maintenance costs. This makes the slightly higher price of heat-treated soil justifiable, as it results in happier customers and lower long-term maintenance costs.

For landscape gardeners who aim to deliver high-quality results with minimal maintenance and no use of pesticides, steamed soil is the right choice.

What do you think? Will you use steamed soil in your next project? Contact us to learn more about steam-treated soil.

The post Why Landscape Gardeners Choose Steamed Soil for Park and Garden Projects appeared first on SoilSteam International.

Why Steam Treatment?

When soil is moved during construction or agricultural projects, it can carry harmful organisms that spread to new areas. Traditionally, this has led to strict restrictions, including prohibitions on relocating contaminated soil. Now, heat treatment is considered a solution that ensures soil quality while protecting the environment from the spread of unwanted species.

Soil heat treatment involves heating the material to temperatures that kill seeds, plant pests, and microorganisms. This process, which is expected to become part of the Norwegian Standards framework, can potentially revolutionize the handling of problematic soil in Norway.

Picture: Norwegian authoroties have now opened up to recycle biological contaminated soil after heat/steam treatment.

Benefits for the Environment and Society

This initiative represents a win-win situation for both the environment and society:

1. Waste Reduction: Instead of disposing of contaminated soil, it can be cleaned and reused.
2. Preservation of Topsoil: Soil is a valuable resource, and reuse contributes to sustainable resource management.
3. Prevention of Environmental Damage: Heat treatment prevents the spread of harmful species that can threaten biodiversity and agricultural productivity.

The Way Forward

For this method to succeed, collaboration between public agencies, contractors, and technology developers is crucial. The Norwegian Food Safety Authority highlights the importance of planning and thorough mapping before project initiation, as well as the need for permits when moving contaminated soil.

This is encouraging news for stakeholders in construction and agriculture, demonstrating that Norway is taking concrete steps to address future challenges sustainably. Heat treatment of soil could become an example for other countries seeking to combine environmental protection with efficient resource use.

We now look forward to the implementation of a Norwegian Standard for soil heat treatment – a vital step towards a greener future!

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Challenges in Soil Quality
One of the biggest concerns today is the declining quality of arable soil. Globally, around 33% of soil is degraded due to erosion, pollution, salinization, or nutrient depletion. This degradation is mainly caused by unsustainable agricultural practices, heavy use of chemicals and fertilizers, and harmful organisms in the soil. These practices lead to a loss of soil biodiversity and a decline in essential soil organisms that help break down organic matter and cycle nutrients.

Loss of Volume and Soil Sealing
Urbanization has also led to increasing soil volume loss. As urban areas, roads, and industrial zones expand, large land areas are covered with asphalt, concrete, or other impermeable materials, known as soil sealing. In Europe, an estimated 890 km² of soil is sealed annually, reducing arable land and the soil’s ability to absorb water, increasing flood risks, and lowering water storage capacity.

Focus on Sustainable Soil Management
There is a growing trend toward sustainable soil management methods, such as agroforestry, regenerative agricultural practices, and minimal soil tillage (plowing). These methods aim to restore soil structure and organic content, helping to increase soil fertility, water retention, and carbon storage capacity. Sustainable management can also help slow down erosion and reduce soil volume loss in the long term.

Innovative Technologies and Solutions
Technological advancements play a vital role in preserving soil quality and volume. Numerous innovative solutions have been introduced, such as digital soil monitoring, the use of drones to analyze nutrient and moisture levels, and the development of machinery that can clean contaminated soil and reclaim arable land. An example is our SoilSaver, which effectively combats harmful microorganisms without polluting the soil with chemicals. It also removes seeds and plant parts from invasive species, which would otherwise require the disposal of large volumes of soil.

The Way Forward
Ensuring the quality and volume of soil requires collaboration between agriculture, the technology sector, and governments. World Soil Day provides an opportunity to reflect on how we can better care for our most valuable resource. Supporting sustainable management practices, increasing the use of innovative technologies, and engaging society in soil conservation may be the key to maintaining productive soil for future generations.

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No Weeds in Steamed Soil

Extensive testing of various soil types, including construction soil mixed with sand and peat, has shown that no weeds survive in steamed soil. In a recent experiment conducted by SoilSteam International, the soil was steamed to 70°C and 90°C, and ryegrass was then planted in it. The results clearly showed that weeds did not sprout in the steamed soil, while in the control group (non-steamed soil), significant amounts of weeds began to grow after just two weeks. This highlights that soil steaming effectively eliminates weeds and provides a clean foundation for plants to thrive.

Better Growing Conditions in Steamed Soil

But it’s not just the absence of weeds that makes steamed soil advantageous. The tests also revealed that plants grown in steamed soil exhibited much better growth compared to those in non-steamed soil. Specifically, ryegrass planted in steamed soil grew significantly better—in terms of height, density, and color. After about a month and a half, the ryegrass in steamed soil had reached 24 cm in height, while in the non-steamed soil, it only grew to 16 cm.

Improved Root Development

Another important finding was that the plants’ roots developed much better in steamed soil. When the ryegrass pots were emptied, the root systems were found to be more extensive and better developed in the steamed soil. This indicates that plants have better access to nutrients and water in steamed soil, which promotes healthier growth.

Conclusion

Soil steaming is a highly effective method for eliminating weeds while also providing plants with better growing conditions. In the experiment, ryegrass grew faster and denser in steamed soil, and no weeds survived the steaming process. This makes soil steaming an ideal solution for anyone looking to grow fruits, vegetables, or flowers without worrying about competing weeds.

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How much soil needs to be excavated?
Japanese knotweed has a complex root system, known as rhizomes, which can extend deep into the ground. To ensure that all knotweed is removed and cannot regrow, it is usually necessary to excavate at least 3 meters in depth and up to 7 meters in width from the plant’s origin. This is because even small fragments of the rhizomes can lead to new growth. If not done thoroughly, the plant can easily resprout and continue to spread. Consequently, up to 460 m³ of soil may need to be excavated to remove a single plant. This equates to 23 truckloads!

Disposing of soil containing Japanese knotweed is not sustainable. Disposal involves significant costs, both in terms of transport and landfill fees. Additionally, it increases the need for new landfill sites, which in itself is an environmental burden. Soil that is disposed of Japanese Knotweed must be treated as special waste, and improper handling can lead to the plant spreading from the landfill site to nearby land.

Landfilling this soil is not sustainable. Disposal contributes to increased CO₂ emissions due to transport, and it deprives us of resources in the form of soil that could otherwise be used in construction projects. It becomes a short-term solution with negative consequences for both the environment and the economy.

A much more sustainable approach is to recycle the infested soil with a SoilSaver. The SoilSaver method involves steam-treating the soil so that Japanese knotweed (and other weeds) do not survive. This process results in the soil being reused instead of going to landfill.

Benefits of SoilSaver include:

1. Reduced costs: By recycling the soil, transport and disposal costs are significantly reduced. The soil can be reused locally, making it more economically viable.
2. Environmental benefits: Reusing soil contributes to reduced CO₂ emissions. Both transport and the need for new landfill sites are minimized. Additionally, reused soil binds CO₂, while landfilled soil emits methane. Recycling with SoilSaver also reduces the need to extract new soil from natural sources, which helps protect the environment.
3. Sustainable resource use: By recycling the soil, resources are utilized more effectively. Soil is a valuable natural resource, and reusing it allows for better management of our natural resources.

Excavating soil infested with Japanese knotweed has often been necessary to prevent the plant’s further spread. However, disposal is an expensive and non sustainable solution. Recycling the soil with technology like SoilSaver is a more sustainable alternative that reduces costs, protects the environment, and ensures the effective removal of the plant. Using such solutions is essential for managing invasive species in a responsible and forward-looking manner. Contact us to learn more.

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Dokka Entreprenør used “SoilSaver” this summer to steam soil and eradicate invasive plants, allowing the soil to be reused instead of being sent to landfill. This method was chosen for a road project to reduce the need for transportation and CO₂ emissions. The SoilSaver machine can treat up to 20 tons of soil per hour, and 4000 tons were “saved” from disposal.

SoilSteam and Dokka Entreprenør plan to use this technology in more projects in the future. Standard Norway has also established a committee to develop a standard for thermal soil treatment, which is expected to be completed in 2025. Read more here: https://anleggsmaskinen.no/2024/10/forst-i-verden-damper-jord-i-veiprosjekt/

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