Claire Chenu: ‘Take a closer look at the earth beneath your feet’

Claire Chenu speaks with authority and conviction when it comes to soils. Head of the scientific council for France’s national research programme on soils, and professor of soil sciences with AgroParisTech, she is Special Ambassador for the International Year of Soils 2015. She means to speak out on behalf of our planet’s soils – before it’s too late. 

Why the interest in soils?

Because we all depend on soils! We may not be aware of it but soils are essential to our food, fiber, water and many other needs. On a personal level soils interest me because they are alive. Soils are considered to be the last frontier in terms of Earth’s biodiversity. From the surface, soil is brown and doesn’t look like much, but take a closer look and in fact it has a very complex architecture with pores, holes and canals. It is a three-dimensional world where a very wide diversity of organisms exists. Not all are active but many survive there waiting for favorable conditions.

Is that something we should care about?

One of the most important lessons I have learned, and one that continues to amaze me, is how multifunctional soils are. On a base level soils are the medium in which plants grow and we need that for food production, energy production, and fiber production. But they also play an extensive role in the water cycle and have a major importance in regulating the quantity and quality of water. Soils are also where we dispose our wastes. Many of our antibiotics have come from bacteria and fungi that have been isolated in soils.

What do you want to achieve as Special Ambassador for International Year of Soils?

I consider soil security one of the great global issues of our time – along with food security, water security, energy security, biodiversity maintenance, and climate change. All of these issues are very strongly interconnected but soil security is not getting the same coverage as some of the other issues and it’s time for that to change. We are linked to soils in many basic aspects of our everyday life. My goal is not to inform soil scientists, but people who do not pay attention to soils normally – stakeholders, decision makers, citizens.

You mentioned soil security is connected with other global issues. How so?

A good example would be climate change. I think everyone is concerned with climate change right now but not everyone knows that soil contains the largest terrestrial carbon pool. Nearly three times as much carbon is stored in soil than in the atmosphere. So small changes in soil carbon can have a large impact on the amount of CO2 in the atmosphere. Managing soils properly can limit the increase of CO2 concentration in the atmosphere and even reduce it. This is a major issue in the news: many countries are going address it in the next COP21 this December. The major global issue where soil plays a role is food security. 

How exactly does soil affect food security?

One thing that really struck me (at a recent international panel discussion) was when a participant said that in her country, one of the only treasures is soils. They do not have expensive agricultural equipment or huge cattle holdings, so their main capital is the soils they are using to grow food. I think this really sums up how important soils are to our future food security. Soils are the medium in which plants grow. They provide water and nutrients to growing plants, making them the basis for healthy food production.

What is the status of soils in the world today?

The world status of soils is quite scary. Unfortunately, around one-third of the world’s soils are degraded, from threats like erosion, contamination, compaction, loss of organic matter, or desertification. This is especially bad because soils are a limited resource. Only 22 percent of the surface of emerged land is suitable to use for agriculture because either the slope is too steep or it is too cold or it is a desert or the soil is too thin or under water.

What is harming soils the most right now?

Erosion is the most important problem we face on a global scale, and it has dramatic consequences. When soils are being eroded, the layer of soil that leaves the landscape is the top layer and this is the richest in organic matter. Erosion is associated with a loss of organic matter, which creates loss of fertility, and this is directly related to the capacity to grow plants and food.

Can’t soils be restored?

The limited land that is suitable for growing food has been considerably degraded and decreased over the last 50 years, and the process continues. The priority is to halt soil degradation. We need to act in both directions: reduce soil degradation and develop soil restoration. There is scientific knowledge to build upon to develop soil restoration strategies.

Cities around the world continue to expand, covering over soils. What can be done?

In most countries, the cities were built where the land was fertile and agriculture was prosperous. Now cities are expanding over the best soils. Land planning at present is based on very simple considerations of what is practical in terms of infrastructure. There is no consideration of soil quality and its ability to perform different functions. It could be a major improvement if soil quality was considered in land management. A very simple example:  building on polluted land could be more reasonable in many areas. Land planners need a better understanding of soil functions. Better characterization of soil quality would promote sustainable land management.

What are the challenges for Eastern Europe and Central Asia?

In Eastern Europe, contamination problems are huge because of the history of industry. It’s the same as Western Europe because people were not aware of the chemical compounds used in industrial activities. Limiting present contamination and rehabilitating polluted sites are major issues. And there are efforts now to decontaminate soils and rehabilitate them. Also, in Central Asia, some areas are concerned with desertification and erosion that correspond to general impoverishment and degradation of soils. There is a loss of organic matter and biological activity and hence losses of soil structure and a higher sensitivity of soils to erosion by wind or water.

Desertification in semi-arid areas is very important, as is salinization, especially when soils are irrigated with waters of poor quality.

What would good soil management look like?

Soils are often perceived very differently by different people. Land planners see them as a surface that can or cannot be built on. Farmers see them as the medium where plants grow, and people involved in water quality see them as buffers. But if we manage soils for only one function we degrade them more easily and then hamper them from being able to perform the other functions. For example, if you manage soils in a very intense set of agricultural practices, you may not be able to use them to manage biodiversity or store carbon to reduce greenhouse gas emissions. So, as a first step it is important to promote awareness of the multi-functionality of soils. Good management of soils to preserve their multiple functions and especially that of food provision goes by maintaining or improving their organic matter content and biological activity.

What can people do differently in their everyday lives?

Even people who are not farmers or working directly with soil can do something: be aware and inform others. We can avoid using pesticides in our own gardens, recycle our wastes and use compost, pay attention to how our food was produced, with practices that are harmful to soils or not, try to buy local in order to reduce our indirect use of soils that come from the other end of the planet. If we are involved in our community, in choices of where to build and to recycle, be aware and make sure soils are being considered. Of course we are not working on the same scale as farmers and land managers, but every action counts. 

28 September 2015, Budapest, Hungary


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