Soil degradation: a growing issue
- Natural resources ,
- Biodiversity ,
- Ecosystems ,
- Business & Industry ,
In the international year of soil, Andrew Tinsley and Timothy Farewell provide a reminder that we need to do more to safeguard this natural resource
It is easy to see why soil is poorly understood by environmentalists and planners alike. Despite a modest recognition of sustainability issues, this abundant, natural resource is a fragile one that is, in effect, non-renewable, and discussion of it is dominated by some highly technical science and unfamiliar language and classifications.
Soil is a key part of the biosphere but it generates so slowly it can take 500 years to form 1cm of new material. It is estimated that one heaped teaspoon of soil contains as many living organisms as there are people on the planet. The most popular antibiotics, including penicillin, have come from dirt and a recent study of soil biota – all the organisms that spend much of their life in a soil profile – by researchers at Northeastern University and NovoBiotic Pharmaceuticals in the US found new antibiotics could be produced from sample collected in Maine. It could be argued that protecting the life in soil is no less important and valuable as protecting that in areas of rainforest; we just need to adjust our scales of perception.
It is international year of soils. As such, 2015 presents an opportunity to explore why soil, the third environmental arena, with air and water, is rising up the political agenda.
An old problem rediscovered
Soil degradation, which includes erosion, compaction, the loss of organic content and biota, sealing and contamination, is a familiar problem. Each year, 24 billion tonnes of topsoil is lost globally through degradation and erosion, threatening the futures of entire societies. In the UK alone, there is growing evidence that poor management and development practices are major causes of degradation, perhaps costing as much as £1.2 billion a year, according to a 2011 report for Defra.
The most famous example in modern history of soil degradation and failure is the 1930s “dustbowl” in the US and Canada. Land use was changed from natural prairie, where the grass roots hold and reinforce loose textured soils, to intensive, mechanised agriculture with bigger fields, deeper ploughing and more intensive cropping without traditional rotation, field boundaries or fallow periods. As a result, agricultural land and soil rapidly degraded after a long drought. Moisture was lost, the topsoil structure broke down and the wind eroded the soil.
The hardships faced by the people in the areas affected were exacerbated by the economic depression. The dustbowl years hastened the introduction of the first US soil protection laws with a warning from President Franklin D. Roosevelt that “the nation that destroys its soil destroys itself”.
Although the dustbowl was a natural disaster, it was made worse by human mismanagement. There are also examples of industrial disasters that, as well as killing and injuring people, have almost instantly put large areas of soil resources beyond beneficial use. In April 1986, after an explosion and fire, radioactive materials released from the Chernobyl nuclear reactor contaminated 400,000 hectares of agricultural land, which are now lost permanently to production in Belarus, Ukraine and Russia. The disaster even affected a few areas in Cumbria and north Wales where farming was restricted until 2012 because radioactive caesium-137 from the Chernobyl fallout was found in upland soils. If measures were not taken, it was at least in theory possible for the material to enter the UK food chain through grazing animals.
The Seveso disaster near Milan, Italy, in 1976 resulted in contamination of more than 600 hectares of soil after the accidental release of a dioxin – an environmentally persistent and highly toxic chemical – from a factory. About 2,000 people were treated for dioxin poisoning, while hundreds of thousands of tonnes of contaminated topsoil had to be disposed of in specially constructed landfills. This led to the EU creating the Seveso directives, transposed in the UK through the control of major accident hazards or COMAH legislation.
More recently the explosions in March 2011 at the nuclear reactors at Fukishima, Japan, after a tsunami led to the contamination of 3 million hectares of land with long-lived caesium-137.
The slow disaster
These disasters represent rapid, acute changes to soil systems and produce swift political reactions. However, it is slow, chronic changes to systems, which may take years or generations to be noticed, that have become the concern in Europe and globally. One example is the loss of carbon from soil. It has been estimated that 4.4 millions tonnes of carbon were lost each year from soils in England and Wales between 1985 and 2005, equivalent to 42% of the UK reductions in CO2 under the Kyoto protocol.
Erosion is another issue. Using modelling and field survey data, researchers at Cranfield University reported in 2006 that typical soil erosion rates in England and Wales from wind were up to two tonnes per hectare each year. They also found that up to 10 tonnes were lost due to tillage erosion; as much as five tonnes to co-extraction on root crops and machinery; and up to 15 tonnes from water erosion. The threshold for tolerable rates of soil erosion has been identified at one tonne per hectare a year. Beyond this level, the ability of the soil to function properly and deliver ecosystems goods and services is damaged. It is likely that future extreme weather will increase the rates identified by Cranfield.
Humans now significantly influence many ecosystems on Earth, and more than 85% of the planet’s land has been altered as a result. In the UK, this figure is almost 99%. Natural and human-regulated functions are inter-linked over much of the planet’s surface as “anthropogenic biomes” or, as research body Resilience Alliance terms them, “socio-ecological systems”.
There is growing evidence that the major impacts on soil come from decades of gradual degradation, not singular events. The capacity for soil to deliver key ecosystem services necessary for a sustainable society has suffered through:
- gradual loss of topsoil to erosion;
permanent sealing of soils beneath
compaction through trafficking of heavy
machinery at inappropriate times of the year;
decline of the organic matter content as a result
of changing land management practices; and
- the industrialisation of agriculture and an associated loss of biodiversity.
Where soil biodiversity is lost, there is almost inevitably a loss of soil carbon to the atmosphere as CO2. This exacerbates the problem, as higher temperatures lead to a decline in soil carbon. Climate models suggest the UK climate is changing to one of warmer summers and milder, wetter winters but with an increased likelihood of extreme weather such as heatwaves and intense rainfall. These would put extra strain on soil.
A type of rapid soil erosion in Europe is increasingly recognised as a new phenomenon: not dustbowl but “muddy flooding” as a result of heavy rainfall. Europe is not immune to dustbowl effects, however. One of the more disturbing facts to emerge in recent years is that in several countries, including Bulgaria, Cyprus, Greece, Hungary, Italy, Portugal and Spain, some areas have been affected by desertification, as defined by the UN convention to combat desertification.
Ecosystem services provider
Soil provides a number of vital functions and services. These include:
- “Green” water storage for use by plants and crops.
Supporting diverse species and rich ecological
habitats, including soil organisms.
- Environmental interaction through decomposition and cycling of nutrients.
Providing a platform for construction and
secure foundations, including surface
Protection and storage of buried infrastructure – telecommunications, IT, gas, electricity and
- Carbon cycling, storage and sequestration.
- Filtration of clean water for drinking, locking contaminants into the soil structure.
Providing a treatment medium for human
and industrial organic waste.
Influencing and potentially moderating the
extent and severity of flooding.
- Protecting archaeological and cultural heritage.
- Food, fibre and biomass crop production.
Degraded soils cannot provide the same level of these natural goods and ecosystem services that humans, as “service consumers”, take for granted, but which are vital to the sustainability of society. As Elin Enfors at the Stockholm Resilience Centre says: “Maintaining soil health over time, both in terms of its physical, chemical and biological properties, is crucial for the long-term resilience of ecosystem services, including water regulation, in agricultural and other landscapes.”
In 2011, the UK government issued the natural environment white paper (NEWP). It builds on the findings of the UK national ecosystems assessment, which recognised the degradation of soils that has occurred as part of wider environmental degradation.
The NEWP created the potential for biodiversity offsetting, a system where developers fund the creation of equal value habitat elsewhere if their project has an adverse impact on an environment. Although this may be politically attractive, critics have questioned the feasibility of recreating ancient soilscapes, which take thousands of years to mature in new areas because the fundamental building blocks and ecosystems of these habitats will be missing.
A UK soil strategy?
The 1972 EU soil charter set aspirational standards for soil protection to be included in member states’ national legislation. It was superseded in 2006 by the European soil thematic strategy, while in the same year a draft soils framework directive was proposed. Plans for the directive were withdrawn in 2014 after years of lobbying in the UK by, among others, farmers’ union NFU. Critics said the directive would have placed undue financial burden on nations that had many soil types. Its defenders argued that those countries were the ones that had most to lose in terms of uncosted ecosystem services.
Guidance targeting soil degradation has been produced separately by each of the devolved administrations. The strategies show what is possible where there is the political will. Defra’s Safeguarding our soils: a strategy for England, published in 2009, describes the requirements of the EU soil thematic strategy and sets some key goals for the management of soils in England. It includes the ambitious vision that, by 2030, “all England’s soils will be managed sustainably and degradation threats tackled successfully. This will improve the quality of England’s soils and safeguard their ability to provide essential services.”
In particular, the strategy recognises the decline that has occurred over the past 200 years through intensive agricultural management, development-linked degradation, and contamination from industrial pollution. The report also references a soils toolkit for planners. This has yet to materialise, however.
Due to the timescales of degradation and recovery, and the local “landowner” perspective often taking precedence, region-wide soil degradation is seldom championed as a political issue because legislation is largely targeted at remediation of contaminated soil.
Although there are soil strategies for England, Wales, Scotland and Northern Ireland, legislation focusing on direct protection of soil is almost non-existent in the UK. Indeed, only nine EU countries have specific legislation to protect soils. In the UK, some soil areas are partly protected by incidental inclusion in other legislation and briefing documents, including the Land Compensation Act 1973, Contaminated Land Regulations 2006, Environmental Permitting Regulations 2014, and Sludge (use in Agriculture) Regulations 1989.
Planning for soils
With so little soil-specific legislation, it is perhaps unsurprising that there is limited dialogue between soil scientists and planners. It is particularly frustrating that, although the UK lacks soil protection laws, it has some of the best web-based academic databases in the world available on its soils.
These include the Land Information System, which is maintained by Cranfield University and is an integrated database of soil and climatic data for England and Wales. It provides multi-temporal assessments of topsoil elements to track changing conditions of the soil, as well as a suite of soil maps for specific planning purposes. Some of the maps show how a soil can recover from compaction, the vulnerability of the built environment to soil-related ground movement, contamination from pesticide leaching, and runoff pathways and hydrological flow. Similar information is available for Scotland through the James Hutton Institute’s SIFSS – soil information for Scottish soils – database, which contains information on about 600 soils in the country.
Soils develop over thousands of years, but can be irreparably degraded over much shorter timescales. Better communication to planners and environmentalists of the risks and mitigation strategies to minimise human impact on soil is one step that can be made towards securing a more environmentally resilient society for future generations.
As Matt Aitkenhead, of research centre the James Hutton Institute, says: “Soil is the memory of the land. All of the things that have happened to the land over time are recorded, minutely or in broad strokes, within the soil. Soil is natural capital and the damage we are doing to it directly affects the interest we get back on this capital. We keep dipping into soil capital to keep our economies strong. Can Europe afford to build a new Berlin every year on good quality agricultural land? We must ensure that the memory the soil will have of us in 2015 is a good one – future generations will not forgive us if we fail.”
Andrew Tinsley, MIEMA, CEnv, is an environment and sustainability consultant working on infrastructure-level and national projects, particularly those affecting the defence and nuclear industries.
Dr Timothy Farewell is a geospatial soil and environmental scientist at Cranfield University.
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