Unearthing the benefits of healthy soils and how it can help fight climate change, with Tim O'Hare

Rachael Forsyth and Tim O'Hare

This week renowned soil scientist Tim O'Hare unearths the ways soil is impacted by and can impact climate change.

Tim O'Hare Associates recently won a Pineapples awards for Circus Street in Brighton where a derelict urban market space was redeveloped into a mixed-use neighbourhood space. Tim developed the various soil profiles and ensured they were sourced and installed correctly:

"We're well down the food chain on the consultants that are involved with these sort of things but we take pride in the work that we do".

"I've always felt soil was pretty much the forgotten natural element alongside air and water. Certainly in terms of the amount of monitoring and the amount of guidance and protection it's given it's minimal compared with the other two and at last it's finally being recognised."

He discusses soil compaction, still "the biggest negative impact on soils from the whole construction process" but he is encouraged "they are now taking greater notice of it" with changes to the kit and ways of working used by operatives on building sites.

For back gardens he advises an increase in top soil layers from the old standard 100mm to 300mm, which he says not only good for the environment but for business: "For every garden that doesnt work properly, you have an unhappy home owner ...but multiply it nationwide and imagine the loss of water attenuation we have created.

"If you invest in these things ... as a developer you're not having problems with having to retrofit drainage, take down fences, re-do turfing and all the bad social media and publicity that comes with that."

He talks in fascinating depth about his work on the Queen Elizabeth Olympic park and athletes village, an extensive, high profile and complex job which he has been reviewing to see how the soil has performed and to extract any learnings.

He defends the use of oft-maligned "manufactured topsoil" and how it enables the soil to work as a functioning soil from day one, to support not only plant growth but in time a whole community of fauna.

The soils at the Olympic park now "look feel and smell like natural top soils with all the humic acids working. The earthworm populations are phenomenal!"

"These man-made soils aren't short-term products that need to be replaced or enhanced. The whole aim of a manufactured soil is to be sustainable both in terms of its components that are used (there should be recycled or recovered components), but secondly, they shouldn't be any more demand on resources than a natural soil. In many respects they should be better than a natural soil."

As with all aspects of horticulture, soil is suffering the impacts of climate change, but Tim explains how "vitally important" soils are in terms helping slow its progress: "Soils are the biggest terrestrial carbon sink on earth - there's more carbon stored in the ground that above ground in the forests and so on". He outlines initiatives such as "minimum" and now "zero tillage" approaches.

He discusses the role of Government in protecting soils and outlines the various initiatives to influence and take action on soils in the construction and farming sectors.

Other projects include work on HS2 where among other things, Tim is helping use vast quantities of spoil excavated will be used to create one "of the biggest calcareous grasslands in the country".

"Optimising the soil function and the value of soils is the key message and we can all do our bit to achieve that".

Presenter: HortWeek senior reporter Rachael Forsyth
Producer: HortWeek digital content manager Christina Taylor

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