Dr Jan Peter Lesschen is a senior researcher and project leader on soil and climate at the Dutch institute Wageningen Environmental Research where he focuses on greenhouse gas emissions, soil science, land use and regional scale modelling.
It is estimated that 60-70% of European soils are in an unhealthy state – what is causing this widespread degradation of soils?
It is region dependent, but generally, soil erosion is an important issue, as is loss of organic carbon, soil compaction, and pollution from heavy metals and contaminants.
Why are healthy soils essential to tackle climate change?
Jan Peter Lesschen: From the perspective of climate change mitigation, it is because soils have the capacity to sequester carbon. If compared to their natural state, soils have lost a lot of carbon, especially soils on arable land. By having better soil management, you are able to increase the soil carbon content again and you have carbon removals.
Looking at predictions from the IPCC (Intergovernmental Panel on Climate Change), if we want to reach the targets of the Paris Agreement, then there are no scenarios where you can do this without any carbon removals. So far, it is mainly land use and forestry [the land, land use change and forestry (LULUCF) sector] that are contributing to that and acting as a sink. But that sink is decreasing in the EU, especially because of forest degradation and increased harvests. So, it is not enough, you will need to include soil carbon as well if you want to reach those climate goals.
From the climate adaptation side, soils that are in good condition and have more organic carbon have a better structure and can hold more water, which in drier periods can help prevent damage to crops. They also improve water drainage and prevent issues with water logging when there is a lot of rain.
We are already seeing the effects of climate change much more, and farmers are more aware that they should work on their soil. There is a lot more attention on soils, with soils being a central element of many actions like regenerative agriculture. For farmers, climate adaptation is more important than mitigation, but most sustainable soil practices can improve and contribute to both.
What kind of sustainable soil practices could be implemented?
Jan Peter Lesschen: It is quite region specific, with no single practice relevant everywhere, but in general we should keep the soil covered and have diverse crop rotation, agroforestry with more woods and hedges to sequester carbon, but also create shaded conditions.
Keeping the soil covered increases photosynthesis and carbon input, but that depends on what is possible, like in Mediterranean areas where water availability might be an issue.
The proposed Directive on soil monitoring and resilience aims to restore European soils to health by 2050 – do you think it is ambitious enough? What do you think of the European Parliament’s proposed amendments?
Jan Peter Lesschen: Looking at the summary [of the Parliament’s adopted position on the proposal], I can see that this has been watered down, but regarding some parts I would say this is good as it is more realistic. This is particularly true of the change to the “one out, all out” principle [by which failure to meet any of the criteria would result in an “unhealthy” status], where the Parliament now proposes to have different classes.
This is because in many cases, it takes time for some soil properties to recover. For example, soil carbon is really slow in increasing. So, if you propose an indicator based on the carbon content versus the clay content of soil, but you are in a situation with soils high in clay and low in carbon (which is the case in many arable systems on clay soils), then there would be hardly any possibility to make it a “healthy” soil according to that criterion.
Another example is in the Netherlands, where we have high phosphate soils. Getting them to lower levels takes a lot of time. So I think it is good to have a bit more of a classified system as the Parliament now suggests.
The main criticism is of course how legally binding can it be? It was already a bit unclear and now I think it is even less so, it is more depending on some voluntary action. On the other hand, I would say it is the first step: if it was too ambitious, it might have a high chance of not being adopted at all.
For many of the indicators, many countries do not yet have good data, so if you start with the monitoring, you can then follow up.
The list of guiding principles from the original proposal was good, but also quite general. I think in that way, there are other instruments like with the Common Agricultural Policy and the work of the Commission on the Carbon Removals Certification Framework that might be more incentivising and lead to the uptake of these principles.
We still have to do more on getting the data for monitoring, the quantification of practices, how much do they contribute – there is still quite some discussion about this. Then, who in the end will be liable: the government, the farmer?
The proposal also sets out to harmonise European soil monitoring, why is this an important step?
Jan Peter Lesschen: Under the Soil Mission [EU Mission: A Soil Deal for Europe], there are a lot of projects being funded that will provide many answers. For example, there is not yet a clear, well-accepted definition of what makes soil “healthy” and what the indicators for this are; one important ongoing EU project BENCHMARKS is looking at this.
Sometimes policy goes ahead before the science is fully developed, which is good for setting targets, but can be hard to elaborate on in a practical way. I think with the projects being developed, we will know a lot more in the next five years.
You are involved in some of these projects, can you tell us about them?
Jan Peter Lesschen: The EU-funded MARVIC project is setting up a monitoring framework for carbon farming, where important questions are being addressed, like how to sample and how to quantify, to help harmonise data collection.
I also work with the European Commission on the Carbon Removals Certification Framework, and there is a lot of discussion on carbon farming. It is a chance to get private finance involved in the sector by selling these certifications – this has been criticised from some environmental groups as green washing, but on the other hand, if you set up a very difficult system, no one will take it up.
But most sustainable soil management practices are low risk and will benefit the soil. The main issue is how to quantify it, but that discussion will come.