Jenny Jones is passionate about soil. She has spent 35 years working in Higher Education teaching and researching soil science. She is Chair of the Northern Soils Network of the British Society of Soil Science and is an Honorary Research Fellow in soil science at Liverpool John Moores University.
What have you eaten today? Cereal? Sandwiches? Fries? Chocolate? What are you wearing? Have you been out exploring your natural world locally? If your answer to any of these is ‘yes’ or if you have discovered that some of your clothing is made from wool or linen or other natural fibres, then I would ask you to shout a loud ‘thank you’ to soil. I am deadly serious. If everyone realised how much we need and rely on soil, I might not have had to write this blog.
Soil serves us in so many ways, but we have become so distant from it that we now fail to appreciate its value. So, what does soil do and why am I passionate about it? I shall outline some of the many ways in which soil serves us and highlight how we might be running the risk of losing this critical resource. I hope this will encourage you to feel passionate about it as well.
When I was a child I was fascinated by those small, independent shops that acclaimed themselves as ‘purveyors of fine food’, their boast being emphasised by gold, copperplate writing on their frontage. Soil really should lay claim to being the global purveyor of fine food. It is the purveyor of all food. A combination of the correct balance of nutrients, a good texture, reliable water supply and healthy soil organisms enables populations across the globe to have food, fuel and fibre for themselves and their animals. That is, provided that we manage our soils carefully.
Fast forward to the year 2050 and this capacity to produce food becomes even more critical than it is today. It is estimated that, by then, the global population will have reached 9.6 billion. In the last 50 years the per capita amount of arable land has reduced from 0.45ha to 0.25ha. This means that the challenge for the future is one of a greater number of mouths needing feeding from a smaller land base. So, future increases in agricultural output will have to come from increased productivity of existing agricultural land. This means that those using the land will need to understand the nature and resilience of their soils intimately and will be required to manage their land to maximise their productivity without compromising their capacity to support future generations. This is no small ask.
Here in the UK in recent months we have seen alarming scenes of flooded houses, businesses, streets, and fields. We have shared in the distress of people affected directly by these disasters. We may have contributed to arguments about who is to blame and how we might prevent such events happening in future. There now seems to be a greater imperative given the predicted outcomes of climate change. Soil has a key role to play here yet, once again, this function has been ignored too often. Soil can make an excellent contribution to flood regulation, water purification and reducing soil contamination.
Following the 2014 floods of the Somerset Levels an action plan was produced. High up in that plan was the goal to increase soil infiltration. Infiltration is the ability of a soil to take up water. Increasing that ability means that soils can hold on to water for longer before releasing it more steadily as surface water to drain into streams and rivers. Combine careful management of soil water-holding capacity with judicious tree planting (particularly in the uplands) and you have a recipe for sustainable flood management of catchments. Thankfully, this approach is now being considered more seriously in other parts of the country affected by flooding.
If I was to ask you to do a word association exercise with the phrase ‘climate change’ I am guessing that your answers might include ‘greenhouse gases’, ‘carbon dioxide’, ‘melting glaciers’, ‘flooding’, ‘unseasonable weather’ to name just a few possibilities. I wonder how many would include ‘soil’ in their answers. Yet, soil has a major role to play in the impact of climate change. It can both contribute to it and be affected by it. Soil is the largest terrestrial store of carbon. It contains more carbon than is contained in the atmosphere and terrestrial vegetation combined. That’s a lot of carbon! At the global scale, soils are a major component of the planet’s carbon cycle and can influence the concentration of CO2 in the atmosphere. There is growing concern for the permafrost soils of Alaska, Canada and Siberia. These are perennially frozen soils which are found under 25% of the northern hemisphere. Warming due to climate change is causing these areas to melt with the result that micro-organisms begin to break down the organic matter in the soil and release greenhouse gases. Dr Sarah Chadburn of the University of Exeter summarises this process:
“Permafrost soils contain vast amounts of carbon, nearly twice as much as is currently in the atmosphere. As the permafrost thaws in a warming climate, the soil decomposes and releases carbon to the atmosphere as carbon dioxide and methane. These are greenhouse gases, and they warm the Earth even more. This leads to more permafrost thawing, more carbon release, and so the cycle continues.”
Some of my friends think that my life as a soil scientist must entail handling earthworms a lot of the time. This causes them to recoil in horror. Well, I do handle them occasionally, but I don’t mind. They are amazing creatures and are a visible reminder that soil is an ecosystem in its own right. One quarter of global biodiversity is in the soil, but this does not attract the attention it deserves. It is estimated that a spoonful of soil contains as many soil organisms as there are people on earth. That’s approximately 7 billion organisms at current values. Yet, once again, soil is a victim of poor PR. Firstly, we cannot see most of these creatures so it is very easy to ignore them. Secondly, we equate many of them with the ‘ugh’ factor thus diminishing their value. Worms, mites, spiders, bacteria do not have the cuddly ‘aah’ factor yet their value is inestimable. Over a century ago Charles Darwin extolled the value of the earthworm with its capacity to move soil around and so redistribute plant nutrients. Soil biota is essential not only to healthy functioning of soil, but also to our survival. The life in soil drives life on Earth. Soil biodiversity is a huge biological engine driving processes which are essential for human survival. Consequently, it is essential that we monitor soil organisms to ensure that species do not become extinct. They are critical to the sustained functioning of soil.
Those of you reading this may gain much from interacting with nature whether that’s by just going for a walk, or watching birds, or immersing yourself in a favourite woodland, marshland or dune system. Let us not forget that our ecosystems and habitats are as they are because of the soils that underpin them. My local patch is an estuarine marshland which provides excellent habitats for birds, insects and plants. The nature of my patch is driven by the soils. The marsh soils comprise silts and clays which hold on to water. So, plants that colonise it need to have the tools to cope with waterlogged conditions. The resulting reeds, rushes, and grasses provide habitat and food for species such as Reed buntings, Reed and Sedge warblers, finches and waders. Thus, the biodiversity of my patch reflects the properties of the soil.
Soil is a storyteller. The tales that soils tell are not of myth or fable; they are narratives of what has happened to them or around them, both past and present. Soils are superb archives that, under the right conditions, can provide insight into past environments. How often do we hear stories of metal detectorists unearthing some historical hoard? We are beguiled by the sight of Anglo-Saxon jewellery or coins or similar artefacts. Their persistence within the soil has been aided by the qualities of that soil. Its acidity or alkalinity, its wetness, its texture and its chemistry have all acted to preserve the ancient artefacts. Soil also enables us to explore the environment further back in time by preserving the pollen produced by plants and trees. Seeing pollen that has been in soils or peats for thousands of years is an enriching experience. Much of what we know about the development of vegetation systems in the UK owes its origins to the analysis of pollen in soils and peats from around the country. Similarly, the soils of ancient woodlands represent another valuable archive. Ancient woodlands are ecosystems that are considered to date from 1600AD. This means that the soils underlying these woods have been relatively undisturbed for 400 years. Study of these soils alongside similar, disturbed soils can give us valuable insight into the impact of human activity.
Soil has been described as the skin of the earth. It is an extremely fragile skin. We must conserve it, yet across the globe we hear increasingly dramatic stories of loss of this vital resource. Last year the United Nations reported that most of the world’s soils are only in fair, poor, or very poor condition. And their condition is getting worse in far more cases than it is improving. It is said that soil degradation is the most critical environmental threat to humans, yet how many realise this. It is estimated that globally we have enough topsoil left for only 60 years of food production. We are losing soil, through erosion, at the rate of 25-40 billion tonnes per year across the globe which is a loss of approximate 30 football fields per minute. Some believe that soil erosion is second only to population growth as the biggest environmental problem the world faces. We are throwing away the family silver. We are throwing away our existence.
Key threats to soil across the world include: loss of organic matter and erosion, soil sealing, overgrazing, climate change, contamination (particularly with toxic metals), salinisation, acidification, compaction, inundation and landslide. All of these can conspire to reduce the capacity of soils to provide food, fuel and fibre. Compacted or sealed soils interfere with the movement of water through soils resulting in flooding. They also diminish soil biodiversity. We are still discovering the potential impacts of climate change on soils. Some of these problems can be resolved relatively easily and quickly; others require more protracted changes to land management to restore soils to their productive best. We can no longer ignore these threats.
So, there we are. Soil serves us in many ways, but in ignoring its importance we are putting the human race at risk. December 5th is celebrated as World Soils Day annually. December 5th 2015 marked the end of the United Nations International Year of Soils. It saw the publication of a key report on the Status of World’s Soil Resources which outlined the state of soils around the world. Some of its contents are depressing, but there is a voice of optimism that further loss of the soil resource can be avoided with sustainable soil management. The Secretary General of the U.N. Ban Ki-moon urged everyone
“Let us promote sustainable soil management rooted in proper soil governance and soil investments. Together, we can promote the cause of soils, a truly solid ground for life.”
Next time you tuck into a sandwich, bag of chips or chocolate bar, please spare a thought for the soil resource that provided these goods. We cannot be soil blind any longer. Let us not forget that soil degradation is the most critical environmental threat to humans. SOS – Save Our Soils!