Soil remediation: an issue for feeding the planet and addressing climate change

Eduardo Mansur Director of the Land and Water Division, Food and Agriculture Organization of the United Nations (FAO).

“Land take due to urbanization represents one of the leading global threats to soil. We find this phenomenon in both developed and developing countries. ”

“The private sector has a very important role to play in terms of agriculture and sustainable soil management.”

What solutions could rapidly and lastingly improve and maintain soil quality and availability, which is essential to feed 10 billion people by 2050?

Eduardo Mansur: Due to unsustainable farming practices, lots of soils worldwide have become degraded, seen their productivity drop, and ultimately been abandoned. However, they can be remediated! Provided that there is massive investment, as proposed in our “Voluntary Guidelines for Sustainable Soil Management” report. Adopted in 2017 following an open process by the Global Soil Partnership, it contains ten Guidelines — minimizing soil erosion, salinization, alkalinization, contamination, and improving soil water management — which serve as a reference and provide a vast array of engaged stakeholders with general technical and strategic recommendations. Of course, this above all applies to soils currently being farmed using intensive, unsustainable methods.

Antoine Frérot: Like other natural resources, soils have become a rare resource. Their degradation has multiple causes and their disappearance is primarily down to urbanization and rising sea levels. 30% of the planet’s arable land has disappeared in the space of 40 years. We need measures commensurate to the problems: enriching soils to maintain their fertility, restricting urban sprawl by increasing the density of buildings, developing urban agriculture making it possible to reconvert artificial land cover into farmland, and using farming methods that protect soils while boosting their productivity, such as permaculture.

In addition to their degradation, cultivable soils are becoming increasingly scarce due to urban sprawl and infrastructure expansion, a consequence of global demographic pressure. How can this be remedied?

E. M.: Land take due to urbanization represents one of the leading global threats to soil. We find this phenomenon in both developed and developing countries. In most cases, the developments prioritized on the most fertile soil (habitat, industrial infrastructure, etc.) are carried out without taking into account their high value for agriculture. Yet once soil is covered with asphalt or concrete, returning it to its natural state is a challenge. Hence the importance of tools such as land development plans, designed precisely to prevent this problem. Many countries have them, but their implementation has failed for various reasons. Starting with a lack of political will and instruments for compliance with the recommendations for soil management and occupation. However, there are a host of options available to urbanists and town planners, such as reusing already built-up areas (brownfield) or using permeable cover materials instead of concrete and asphalt. In practice, these professionals must be able to weigh up the pros and cons and ensure that the policy tools are in place to obtain the best possible results. Taking account, of course, of both human needs in terms of urbanization and the need to preserve the integrity of the land and its services.

A. F.: 40% of cultivated land is found in a 20-km radius around cities. While stopping urbanization is unrealistic, we can slow it down or direct it. How? By protecting this farmland in land-use plans against competition from more profitable real estate projects. By making cities and infrastructure more compact. To this end, our Group designs facilities with a small footprint and builds underground infrastructure, such as the wastewater treatment plant in the South of France (Marseille). Another solution consists in reintroducing agriculture into the many unused spaces in a city, such as roofs and basements.

Antoine Frérot Chairman and CEO of Veolia

“To win the climate battle, we must utilize all carbon sinks. Forests are well known; soils less so.”

Can solutions to remediate soils or manage soil scarcity be applied in the same way worldwide? For instance, developed countries have advanced technologies to implement off-ground cultivation, which is not the case in developing countries.

E. M.: Soils naturally differ from one region to another. Their management is directly linked to local farming practices, traditions, the political and institutional framework, and the market forces in effect. Logically, the guidelines and best practices adopted worldwide must be adapted to the local context and environment: know-how, traditional knowledge, resources and technologies, the availability of materials, etc.

A. F.: This also applies to urban agriculture. It comes in many forms: outside or inside buildings; horizontal like the community gardens in São Paulo, or vertical like in New York; manual like in Addis Ababa, or automated like in Japan’s farming factories; using basic farming methods or ultra-modern technologies that maximize yields and minimize inputs, etc. This wide technological diversity allows every country to promote urban agriculture, irrespective of its level of development.

Another of soils’ benefits is that they are a major potential carbon sink. What role can they play in reducing carbon emissions worldwide?

A. F.: To win the climate battle, we must utilize all carbon sinks. Forests are well known; soils less so. As part of the 4 per 1000 research project conducted by INRA (read the article) in which we are involved, one of our aims is to help farmers manage soils better and increase their ability to trap carbon. Of course, over and above processes designed to capture more CO₂, it is essential to reduce greenhouse gas emissions at source.

E. M. : Over and above being an excellent way to mitigate air pollution, carbon storage in soil offers a host of ecological benefits: release of nutrients, water retention, aggregation and absorption of organic and/or inorganic pollutants, etc. Its sequestration also reinforces other ecosystem services derived from soils, such as farming production, drinking water supply and biodiversity, by increasing the amount of organic matter in the soil and thus improving its quality. Through this smart double use of carbon — optimized sequestration in cultivated and degraded soils and a supply of nutrients to soils that are already rich, such as peatlands, black soils, permafrost, etc. — we will meet the challenge of compensating for global emissions.

Veolia is developing numerous initiatives and experiments allowing both more responsible and more effective use of natural resources and soils. Could you give us a few examples of your solutions?

A. F.: For a long time, we have been providing the farming sector with renewable resources to limit its environmental footprint. As an alternative to highly chemical products, we produce fertilizers using organic waste (read the article) in the North of France (Nord-Pas de Calais region); we recycle wastewater to irrigate food crops in Queensland, Australia, which conserves freshwater resources; we produce green energy for aquaculture in Hamamatsu, Japan.
At the same time, our Group has begun to produce animal protein from insect larvae. In France and Malaysia, Veolia is partnering two start-ups specializing in insect farming, which breed fly larvae on biowaste, turning them into oil and flour for fish food.

How is the FAO encouraging more environmentally friendly practices that guarantee food security, such as agroecology?

E. M.: The FAO does not advocate a single approach but rather diversified practices, which take account of local needs and specific circumstances and encourage complementary food systems. We wish to maintain a leading role in promoting alternative approaches to conventional farming. Agroecology is one such approach and must be promoted on the basis of many successful experiments worldwide. The same applies to forgotten crops (cover crops, terrace crops, etc.), all of which play a protective role in terms of food security and nutrition and have a low impact on environmental footprint.

What role can companies specializing in sustainable resource management play in meeting these challenges?

E. M.: The private sector has a very important role to play in terms of agriculture and sustainable soil management. Take the example of the International Code of Conduct for the Use and Management of Fertilizers, recently approved by all FAO member countries. Designed to guide the judicious use of (mineral and organic) fertilizers, it consequently gives a large place to each actor in the sector. If we are able to motivate industry and companies to adopt responsible practices, they will trigger the investment required for the sustainable use of natural resources. Single-handedly, private funding can profoundly transform this global approach and help countries achieve their Sustainable Development Goals.

A. F.: Private companies have a role to play in researching and developing solutions to remediate soils to make them fit for cities or agriculture, practice sustainable and productive agriculture, and create the urban agriculture of the future, which will support food security in cities.
Since 1990, our Group has been developing expertise to give polluted soil a new lease of life. To invent more effective and less expensive techniques, it has begun several research projects for decontaminating soil using micro-organisms or phytoremediation.

More:

Carbon: the new “soil capital” asset
CO2 sequestration in agricultural soils: a solution for tomorrow
Storing carbon and optimising organics yield: the advantages of recovering organic waste