Scientists are embarking on a new study aimed at better understanding the qualities, importance and function of subsoil in maintaining crucial soil health in the face of climate change.

A team at Nottingham Trent University, together with a large European consortium led by UCLouvain in Belgium, wants to investigate how the deeper layers of soil support and interact with what we commonly know as topsoil. 

Life on Earth thrives on the foundation of healthy soils. While lots is known about the role of topsoil – due to the focus of agricultural practices that look at water, air and nutrients –– very little is known about subsoil.

Subsoil sits below the top 30cm, reaching down to 10m in exceptional cases, but is known to play an important role in supporting topsoil and plant growth. 

If topsoil becomes damaged then the supply structure that supports plant growth – water, nutrients, air – can fail and soil can decline and degrade, which can become permanent.  

Topsoil on natural, semi-natural and agricultural land is being damaged by climate change and flooding across the globe – and a lot of topsoil has been affected by erosion, metals and pesticides – and so the researchers want to take action now.

The four-year €6 million 'DeepHorizon' project, funded by Horizon Europe, will involve extensive subsoil sampling across European countries.

The team will measure the biological, physical and chemical properties of subsoils across their different types (organic / mineral) uses (forest, grassland, cropland and semi-natural areas) and climates.

They will also use sensors deployed in subsoils across European countries, monitoring real-time nutrient interaction between the layers before analysing this new data along with existing data on subsoils.

The study will enable the team to quantify actual and potential subsoil functions, as well as soil health indicators, and create, test and deploy innovative solutions to improve subsoil functions at more than 100 test sites across Europe.

'While extensive research has focused on the topsoil layer, the subsoils remain largely unexplored', said Chungui Lu, Professor of Sustainable Agriculture in Nottingham Trent University's School of Animal, Rural and Environmental Sciences.

He said: "We know that subsoil supports topsoil. If topsoil becomes damaged then the supply structure that supports plant growth can fail. We need to know what kind of subsoil supports topsoil better and how climate change and different chemicals and fertilisers are affecting subsoil. We need to closely monitor the subsoil situation and identify the nutrient interactions going on between the layers.

"By unlocking this knowledge we can develop solutions to improve soil health. Our work will help us to promote sustainable subsoil management practices, policy-incentives and guidelines for increasing carbon storage and ecosystem services in subsoils and lead to a better understanding of subsoils for the general public.

"By improving knowledge and consideration of subsoils in general, we will enhance soil health and pave the way for a more sustainable and resilient environment in Europe."

Dr Marcello Di Bonito, a Senior Lecturer in Environmental Sciences at Nottingham Trent University, said: "This is the first time that a large group of scientists, from more than 15 different institutions across Europe, are collaborating so extensively on the role of the deeper soils.

"It's a unique opportunity and being part of this excites us; we are looking forward to starting."

Professor Mathieu Javaux, from the Earth and Life Institute at UCLouvain, said: "A unique aspect of DeepHorizon is its holistic view of soil functioning at the scale of the entire soil profile, from the surface to the deepest layers.

"As coordinator of DeepHorizon, I am very hopeful that by bringing together scientists and companies from different horizons and with different expertise, we will be able to improve the understanding of how the soil system works and provide stakeholders with new tools to manage the subsoil and improve its health."