Supporting our soils
Bruce Lascelles on the critical importance of soil health in land management and climate mitigation
The Corine Land Cover database for 2012 shows that just 6% of the UK is classified as urban, and according to The UK National Ecosystem Assessment: Synthesis of the Key Findings, over half our towns and cities is greenspace. What we use un-sealed land for, and how we manage it, will have a significant impact on how well we adapt to climate change and mitigate activities that are driving it. The UN Framework Convention on Climate Change, in its Introduction to Land Use, acknowledges that land use can contribute significantly to mitigation of climate change.
Bold land management initiatives have been widely promoted in the face of this – for example, the 2019 Conservative Manifesto made a commitment to plant an additional 75,000 acres of trees a year by the end of this parliament. However, there is no single fix. The Natural Capital Committee’s Advice on using nature-based interventions to reach net-zero greenhouse gas emissions by 2050 report states that the solution needs to be integrated, holistic and supported by environmental net gain. One part of the solution (of five highlighted priorities) is that biocarbon stocks in existing soils need to be given greater focus and new stocks must be created – and this should be backed by further research initiatives.
Soils are special
To understand why soils are critical, why the health of our soils matters so much (in particular their carbon content) and what actions we should take, we need to understand what soils are. Soils are a combination of minerals, organic material (dead plants and animals) and living organisms, along with air and water. However, they are much more than the sum of their parts. Soils are habitats and ecosystems; a teaspoonful supports more living organisms than there are people on Earth. These organisms interact and are interdependent, just like life on the surface. If we look at soils in this way, rather than as an inert material, we should treat them more carefully and see them as one of our three critically important natural resources. Importantly, soil is a non-renewable resource which forms at a very slow rate.
Around 95% of food production relies on soils, and they are home to a quarter of the Earth’s biodiversity. Soils absorb and store water, reducing flood risk, and also store more than three times as much carbon as is contained in the atmosphere. They support our landscapes, giving us aesthetic, spiritual, cultural, health, wellbeing and educational benefits, and they preserve our cultural history. The sustainability of the environment is contingent upon soils.
While a huge amount of work is undertaken to study soils, there remains much we don’t know because of their complex and microscopic nature. For example, many commonly used antibiotics (including penicillin) originated from soils, and new antibiotics have recently been discovered. What else do soils contain that we are not yet aware of?
The ability of soils to support and deliver ecosystem services and goods is dependent on their health. This is not about ‘good’ or ‘bad’ soils – it is about ability to function. The diversity of life in soils is linked to their function and, importantly, to their resilience.
Soils have been and are under intense pressure from land management practices, negatively affecting their ability to function. Erosion washes away soils, depleting organic matter and filling ditches and rivers with sediment, resulting in thinner, less nutrient-rich topsoil. Combined with cultivation and drainage, especially of organic soils,
this is reducing a vital carbon store.
Soils are being compacted through pressure and the decrease in carbon weakening structural units. This reduces the amount of rainfall that can be absorbed, thus increasing flood and erosion risk. In Costs of Soil Degradation in England & Wales, Defra estimated that the cost of soil degradation in England and Wales in 2012 was £0.9-1.4bn, mainly as a result of compaction and soil organic matter loss.
Land management as mitigation
If land management has resulted in soil degradation, land management changes are the key to restoring soil health and function, supporting resilience to the impacts of climate change and the ability to retain and store more carbon – which itself makes them more resilient. This has to be seen as a win-win strategy, and society must learn to use and manage soil resources in a sustainable manner to secure a healthy and sustainable future. Sustainable land management as part of a holistic approach needs to be our focus.
This will require the selection of the right land use for any biophysical and socio-economic condition, and at the heart of this we will need healthy functioning soils that are capable of supporting and providing multiple benefits.
The changes required will come from a variety of initiatives: tree planting (the right trees in the right places), rewetting our drained wetlands, and protecting and restoring our remaining peatland. All soils can play a part in securing a better future. Different agricultural practices, such as reduced tillage, can improve soil and support climate change adaptation requirements, as well as increase carbon levels (see the 4 per 1000 initiative launched at COP21: www.4p1000.org). According to Natural England’s publication Carbon storage by habitat: Review of the evidence of the impacts of management decisions and condition of carbon stores and sources, land use changes – such as from arable to pasture – can result in soil organic carbon levels increasing. This will be key, but there is also potential for increasing CO2 fixation as inorganic carbonate in soils which, for example, contain fine concrete particles.
This potential will be realised at different scales (as long as the practices adopted are adapted to the local conditions), from those associated with large land holdings to urban pocket parks and linear features (for example, the soft estate associated with our national road network is around 30,000ha, and Highways England has committed to biodiversity net gain by 2040). The positive effects of land management on soils, including how soils are handled and re-used sustainably, needs to be seen as part of the solution moving us towards zero-carbon and resilient masterplanning and how local authorities and the government holistically respond to the climate emergency. This will only be achieved through collaboration and partnerships.
As Franklin D Roosevelt said, “a nation that destroys its soils destroys itself”. We know how important our soils are; now is the time to act at scale and with pace to ensure a sustainable future.
1 teaspoon of soil supports more living organisms than there are people on this planet
Around 95% of food production relies on soils
1/4 Soils are home to a quarter of the world’s biodiversit
Soils store more than 3 times as much carbon as is contained in the atmosphere
The cost of soil degradation in England and Wales in 2012 was estimated to be £0.9-1.4bn
There are resources available to find out what sort of soils occur where you live: go to www.landis.org.uk/soilscapes for England and Wales; for Scotland, look at soils-scotland.gov.uk/data/wrb
Bruce Lascelles is an experienced soil scientist and is the incoming president of the British Society of Soil Science.