8 minute read
Regeneration game
Cattle grazing at Holnicote Estate, Somerset. © National Trust Images/ Nick Upton
National Trust Soil Consultant, Felicity Roos, argues that a holistic approach to soil management across both rural and urban areas is vital in the face of climate change and biodiversity loss.
“Despite all our accomplishments, we owe our existence to a six-inch layer of topsoil and the fact that it rains.” – Paul Harvey
Healthy soils deliver the ecosystem services that enable life on earth. Soil filters and regulates the discharge of rainwater to prevent flooding; it is capable of storing large amounts of carbon and other greenhouse gases (GHG) that help to regulate climate; it buffers against pollutants, thus protecting air and water quality; and it provides us with essential construction and manufacturing materials. Around 95% of our food (nearer 99% if you are vegan) is grown in soil. We drink coffee, grown in soil, from a cup that is essentially baked soil (clay).
Soils are also one of the main global reservoirs of biodiversity, with 59% of living organisms in terrestrial ecosystems spending some, or all, of their life in the soil. This makes it one of the most important and biodiverse habitats on earth – about which we know the least.
However, as for all other pools of biodiversity, soil biodiversity is at risk through loss of habitat, with around 33% of soils globally now seriously degraded, and significantly more in poor condition. In 2015 it was estimated that soil degradation costs the UK around £1.2 billion every year. This is critical, not only for food production but because it is the soil biology that drives and enables the related ecosystem services that we rely on.
Healthy soils are central to enabling the National Trust to deliver its ambitious objectives for people and nature, so that it can be here for everyone, for ever. We need healthy and resilient soils to help mitigate the impacts of climate change, with its inherent risk of increased floods and droughts, and to provide habitats for nature to thrive. The Trust’s gardens and property teams have a vital role to play to improve soil quality on the land we manage in-hand, but we also recognise how important it is to work with farm tenants to improve soil health. This, in turn, can help slow the flow of water across land in times of flood, and hold water in the landscape in times of drought.
Soil, at its most basic level, is a porous material that is made up of varying proportions of sand, silt, clay, and organic matter. The differing proportions give different soils their distinct characteristics as peats, sands, podzols, and more, with over 700 individual soil types recognised in the UK. Large areas of Scotland and upland areas are dominated by peaty, thin, acidic soils that support open scrubby vegetation dominated by heather and mosses; lowland, nutrient-poor, sandy soils give us bracken heaths; and rich alluvial flood plains support species-rich meadows. The distinct properties of soils shape the habitats above them and each has its own unique biodiversity.
These sand, silt and clay particles give a soil many of its physical properties, but it is the soil organic matter that is critical for soil health as it supports and feeds the soil’s biology, and it is often this fraction of soil that has been most degraded. Soil degradation and the loss of carbon (organic matter) from soil began with the advent of agriculture over 7,000 years ago, with the global loss of soil carbon since 1850 estimated at around 66 gigatons (±12), mainly caused by land use change that began with the mechanisation of agriculture after the Second World War. The exportation of European methods of agriculture to other parts of the world, with very different climates and vulnerable soils, has accelerated the global rate of soil carbon loss and degradation. This global decline in soil quality is now being compounded by climate change and pollution, with micro- and nanoplastics and ‘forever chemicals’ emerging as significant global concerns.
In an undisturbed natural system, the soil organic carbon pool is in equilibrium, with seasonal losses and gains in balance. Any disturbance to that system – a forest fire, digging by animals, or ploughing to plant crops – causes disruption that results in losses in soil carbon. Soils are highly resilient and can survive short-term shocks, but they struggle to recover from continued disturbance such as annual ploughing and other agricultural activities.
The diversity of soil types means there is no one-size-fits-all answer to sustainable soil management, hence actions need to be tailored to location, land use, and soil type. This is where movements like regenerative agriculture (Regen Ag), agro-ecological farming, and nature-friendly farming have much to offer.
Regen Ag holds, at its core, “the intention to improve the health of soil or to restore highly degraded soil, which symbiotically enhances the quality of water, vegetation and land-productivity”. It isn’t constrained by the prescriptive limitations that exist in some other agricultural models, such as organic farming. This means that practitioners are able to choose the practices that best suit their soils and systems. However, the lack of definition around what ‘regenerative’ means is one of the main criticisms of the movement since it is hard to define whether a farm is ‘regenerative’ or not.
Principles of good soil management followed by Regen Ag:
1. Minimise disturbance (physical and chemical)
2 Protect and cover the soil at all times (with living plants or mulch)
3. Maintain living roots
4. Encourage a diversity of plants, to help feed a diverse soil biology
5. Integrate animals, be that livestock or nature, to help drive ecosystem services
(Adapted from Dirt to Soil by Gabe Brown)
Shifting a farm from ‘traditional’ practices to nature-friendly farming or regenerative agriculture is not necessarily a simple transition. It might require investment in new equipment that can be a large barrier to farmers currently facing financial pressures. But one of the greatest challenges is that it can require a significant paradigm shift in attitudes towards land management. Currently, many land management decisions are influenced by a Victorian attitude of ‘taming nature’ and making everything neat. Farmers and landowners are sometimes reluctant to let their hedges grow out to benefit nature, because they have always held the belief that a neat hedge is ‘right’ and they worry about being judged as poor farmers for having ‘messy hedges’. It’s a similar problem in urban areas where many homeowners like neat gardens, and they expect the council to keep grass on verges and in communal areas mown short, with weeds sprayed, which removes vital habitat and food for insects and birds.
We need a shift towards a more holistic land-sharing model of land management, with well-managed soils and room for nature around both housing and food production. This will require a social science-informed campaign to change people’s attitudes towards what good management looks like in both urban and rural areas. A lack of knowledge need not be a barrier to change. We now need to inspire and empower people to act.
Returning to soil, we understand both the principles and practice of good soil management, yet adoption has been slow despite work by many organisations such as the National Institute of Agricultural Botany and the farming press. Government subsidies such as the Environmental Land Management scheme in England are also leading to positive change. Restoring soil plays a critical role both in mitigating the impacts of climate change and restoring nature. Sequestering a fraction of the soil carbon we have lost will help reduce annual GHG emissions. We must continue to advocate for the importance of soil health and the many benefits it can offer to the farming community, nature, and society. We need that message to be universal and to come from multiple sources.
Felicity Roos is National Consultant – Soil at the National Trust. She is interested in the role of regenerative agriculture and holistic land management in combating climate change and restoring the environment.
