FAQ

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all of your questions

Below we have listed frequently asked questions and answers. Feel free to contact us if your answer isn’t answered here!

Yes. We use nothing more than water and heat, to create pure steam. We use no chemicals.

Soil steaming is energy intensive. Heating the soil from 10-20ºC up to 75ºC demands a lot of energy. We’re finding ways to reduce the energy requirement, but energy accounts for much of the cost - around €10,000 per hectare. That’s relatively expensive when compared against existing farming operations, but consider this: those operations are annual, while soil steaming is needed only once every three to five years. On a like-for-like basis, soil steaming presents an attractive return on investment.

Our current machines use diesel, propane or, in the stationary machine, biogas. We want to move away from fossil fuels, so we’ve started a project to investigate the potential for hydrogen as a fuel. But even with our existing fuel sources, we have calculated that produce grown using soil steaming offers a smaller CO2 footprint than conventional produce, thanks to the benefits (increased yield, longer storage life, reduced use of crop inputs) it delivers.

The soil steaming process raises the temperature of the soil to 75ºC. But within 24 hours, the soil temperature returns to normal and field operations can continue.

We expect long-term weed control to be one of the main attractions of soil steaming. Consider this - one cubic metre of soil might contain 100,000 weed seeds, all dormant and awaiting the right conditions for germination. This weed seed bank can result in a fresh bout of weeds from every field operation, prompting further control by mechanical or chemical means. But if that cubic metre of soil is subjected to steam, at 75ºC, the seed bank is permanently eliminated. The only weeds appearing after treatment will be wind-blown. To keep the weed seed bank at a negligible level, we recommend soil steaming every fifth year.

No. Fumigation relies on harsh and potentially hazardous chemicals. The only chemical used in soil steaming is water. What’s more, soil is usable within 24 hours of steaming, compared to at least a week with fumigation.

We’ve seen weeds, insects and diseases quickly develop resistance to modern plant protection products, throwing control programmes into jeopardy. But because steaming is a physical process, rather than chemical, it’s much less likely that an organism will develop heat resistance. Our research will continue. But based on our 25-year experience with steam, and its 100-year history, we don’t expect steam resistance to become a worry for anyone.

Fewer weeds and higher yields. Our technology removes 96-100% of weeds and seeds in the soil. We’ve seen crop yield increases of up to 74%, with a minimum increase of 20% across all crops. Steaming also eliminates fungal spores and nematodes. This ensures most root vegetables enjoy a longer storage life, reducing post-harvest waste and increasing marketable yield.

Many farming operations involve machinery that is potentially hazardous. But good farming practice demands properly trained operators and appropriate risk management. Soil steaming is no different and SSI machines incorporate appropriate safety features as standard, including software that will lock out an untrained operator.

We’re planning further demonstrations of the technology in Europe and the US. Follow our blog and our social media feeds to see when we’re coming to a field near you!

Steam is a very effective steriliser. That’s why it’s used in hospitals and other places where utmost cleanliness is essential – there is little, if anything, that can survive steam’s high temperature. But we don’t want completely sterile soil. We’re looking for a lower level of cleanliness – pasteurisation, the same process we use to preserve milk. By heating to no more than 75ºC, we can eliminate harmful pathogens, nematodes, weeds and seeds, while having little or no effect on beneficial soil organisms.

Steaming soil reduces the need for insecticides and other plant protection products. Some of these have been implicated in pollinator decline. Any reduction in their use and application is welcome. Steaming itself has no effect on insect numbers.

No. We worked with the Norwegian Institute of Bioeconomic Research to understand what happens to earthworms during a soil steaming operation. Their scientists conducted a trial in 2008. They concluded that the slow process of steaming, combined with the large equipment involved, generated soil vibrations that effectively ‘warned’ the earthworms to move deeper into the soil. When soil temperatures were back to normal, the earthworms returned.

Every agricultural operation that involves soil has the potential to cause damage. Soil steaming is no different, so it’s important to use it responsibly. We suggest soil steaming is conducted no more regularly than every third or fifth year, using equipment that can maintain a soil temperature of no more than 75ºC.

All organic vegetables, fruit and berries show a profit after soil steaming, as the crop increases dramatically when it doesn’t have to contend with pathogens. But in conventional situations too, soil steaming can often prove a viable operation for vegetables, fruit, berries, herbs, flowers and seeds.

Yes – the steaming process kills both weed seed and weed roots. But as we steam to a fixed depth, there is no effect on anything beyond the steaming zone.

The big issue with weeds is the soil seedbank, rather than airborne seeds. Over many years, soil tillage distributes dormant weed seeds throughout the soil profile. Traditionally, the only way to control these has been after germination, using chemical and/or cultural controls. Soil steaming eliminates at least 96% of this seedbank, along with fungi, nematodes and other soil-borne pathogens. While airborne seeds that arrive after steaming won’t be controlled, the elimination of the seedbank resolves – at a stroke – most of a farmer’s weed burden.

We’re still looking at this. Because there are no weeds on steamed soil, leading to less competition for nutrients, we think it might allow reduced applications. We’re also aware of some published research that suggests the demand for nitrogen increases following soil steaming. So it’s something we need to understand better, which is why we’re focusing further trials on this very issue.

As with any agricultural operation involving soil, the best time is (a) when the soil is workable without risk of damage, and (b) there’s no growing crop. Thus before planting or after harvesting is the most suitable time, particularly if the soil is warm and dry – these are good conditions for

Yes.

We’ve thought long and hard about how best to bring the benefits of soil steaming technology to farmers. Initially, our machines will only be available to lease – which has the added benefit of maintenance being included.

As with any leased machinery, the user undertakes the simple daily maintenance tasks. These are easy to complete. More advanced maintenance is handled by Soil Steam, under the leasing agreement.

We’re expecting to make our first deliveries on farm during 2022, once further trials (delayed by Covid) are completed during 2021. Customers are already getting their names on a waiting list – contact us (through the contact page) to join them!

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