Conserving the soil, one of the great challenges facing science and humanity

Originally published in The Conversation in Spanish.

Achieving the health of all European soils by 2050 is the challenge set by the Soil Monitoring Act, a directive proposed by the European Commission in July 2023. On 11 March, the European Parliament adopted its draft position on this regulation, which aims to promote soil conservation and restoration.

In the absence of final agreement, it seems that preserving soil health as one of the major challenges facing our society is finally starting to be taken seriously. The ambitious objective will be addressed by establishing a robust and coherent monitoring framework for the whole territory of the European Union.

Schematic cross-section of the earth. Soil is a very thin layer of about 1 m of continental crust, but its role is essential for life on the planet. MaxKario / Wikimedia Commons, CC BY

For those of us who study soil this is welcome news. For the general public, however, the subject remains largely unknown.

The substrate that sustains us

Soil is that very thin layer of the lithosphere (1 metre or so) that supports all life in the terrestrial environment of the planet. It is the substrate where all the plants that make up the base of the trophic pyramid, in which humans occupy the apex, grow.

It is also the intermediary between the inert mineral world, the atmosphere (the gaseous layer surrounding the earth) and the biosphere, responsible for connecting the three and for life as we know it.

It also acts as a refuge for a large part of the planet’s biodiversity and is one
of our great allies in the fight against climate change, as it is the second
largest carbon sink after the oceans, with enormous potential to continue sequestering carbon.

A food web starts at trophic level 1 with primary producers such as plants. The soil is responsible for sustaining the production of this base trophic level. Roddelgado / Wikimedia Commons, CC BY

Why is it so important to preserve it?

Today, more than 60% of European soils are unhealthy. In recent decades, global population growth, unsustainable land management, climate change and extreme weather events have accelerated soil degradation.

This scenario means a gradual loss of the biosphere’s capacity to produce food, livestock feed and fiber. Other services directly provided by the soil, such as nutrient cycling, carbon sequestration, pest control or regulation of the water cycle, are also undermined. This is costing the European Union at least 50 billion euros a year.

The problem is that, despite its importance, it is a fragile and practically non-renewable resource, as its recovery process is very slow. Once degraded, it takes centuries to recover. Therefore, conserving it is much more cost-effective than restoring it.

What challenges does science face?

We are faced with a huge black box that we need to unravel if we are to achieve the ambitious goals set out in the Soil Monitoring Act. We are not dealing with a system that is easy to study, but with a three-dimensional physical matrix of great biological and chemical complexity and high spatial heterogeneity, where thousands of species coexist, representing all kingdoms of life.

This complexity is compounded by logistical difficulties in the study of these subterranean ecosystems. These can only be overcome through the combined use of different methodologies (observational, experimental, models, inventories), which requires a lot of effort and interdisciplinary and international collaboration.

On the other hand, we still need to learn more about how they function in order to predict future responses to global change. Current prediction models represent the soil in a very simplistic way from a biological point of view. To realistically integrate its complexity, we need more data, taking into account the heterogeneity of this system.

Another challenge is to generate universal indicators of degradation, beyond those that have already been proposed, such as the ratio of carbon to clay. Again, research is needed to develop reliable indicators that can be used in decision-making.

Finally, it is urgent to study and design strategies to assist the soil and accelerate its recovery. This is a challenge for science, considering that the process of soil formation (pedogenesis) takes centuries to millennia.

This article was originally written by Jorge Curiel Yuste (BC3 – Basque Centre for Climate Change) on The Conversation.