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CHAPTER 3 : THE IMPORTANCE OF SOILS & SOIL FUNCTIONS
3.1 The word 'soil' means different things to different audiences. For many people it is just dirt or mud under their feet; for farming communities it is the basis for their livelihoods; for developers it can be overburden or spoil; for engineers it forms the physical foundation for buildings and infrastructure. By contrast with various other aspects of our natural heritage, soils can be held under private ownership and subject to varied land management and land use activities. There are therefore clear economic and ecosystem values associated with the properties and uses of soils.
3.2 Soil is made up of mineral particles, organic matter, water, air and living organisms. Soil is an extremely complex, variable and living medium. It forms an intricate habitat for macro- and micro-organisms and in fact there is more biodiversity in soils than in any other terrestrial habitat on earth.
3.3 Soils are at the heart of all life: they cover most of the natural terrestrial world and form the foundation of all terrestrial ecosystems, supporting key processes in biomass production and mass exchange with atmospheric and hydrological systems. Soils are valued both for their functional roles ( e.g. support to habitats and species, provision of ecosystem services) and for the diversity of their intrinsic physical, chemical and biological features. Also implicit in their long stewardship is the recognition that soils are a finite non-renewable resource.
Soil functions
3.4 The soils of Scotland provide a wide range of environmental, economic and societal benefits. The term soil quality is conventionally defined as the ability or fitness of a specific kind of soil to carry out the functions listed below.
3.5 Providing the basis for food and biomass production
This is the most obvious and tangible of all the soil functions and the one to which it is easiest to attribute an economic value. The agriculture and forestry industries are key parts of a sustainable rural economy. Healthy soils and sustainable management of existing soil resources enable these industries to produce quality outputs.
3.6 Controlling and regulating environmental interactions - regulating water flow and quality.
This includes the storing and filtering of water by soils which helps protect water and air quality. River basin management is a requirement under the Water Framework Directive and the maintenance of key soil filtering and transforming functions are of fundamental importance.
3.7 Storing carbon and maintaining the balance of gases in the air.
Large areas of peaty and organic soils mean that Scotland's soils are a major sink and potential source of greenhouse gases and contain the majority of the UK's reservoir of terrestrial carbon. Warmer climates and more intensive land use can increase loss of carbon from soils to the atmosphere. We need to ensure that our soils do not become net emitters of greenhouse gases and further accelerate climate change. We should manage our soils to maximise this 'environmental service'.
3.8 Providing valued habitats & sustaining biodiversity
Soils are a reservoir of huge biological diversity, but the contribution of many soil organisms to ecosystem services is largely unknown. Given its scale, the key to conserving soil biodiversity is to manage and protect soils so as to conserve their functions (nutrient supply, water retention and filtration etc.). Soils also support a number of terrestrial habitats of international significance and indeed should be viewed as being an integral part of those habitats. Habitats and associated landscapes such as blanket peatlands, montane habitats, native pine woodlands and machair grasslands underpin Scotland's tourism industry.
The large and unexplored diversity of organisms in soil also represents a potentially valuable genetic reservoir of newly discovered organisms, enzymes, pharmaceutical and other bioactive compounds that might be useful in a wide range of biotechnological industries.
3.9 Preserving cultural and archaeological heritage
Soils provide a record of past environment and previous cultural influence on them. They also provide a protective cover for subsurface archaeological remains. Scotland has a distinctive range of soils as a result of both specific environmental influences and a long tradition of soil use. In some circumstances soils, such as machair soils or the heavily improved soils of gardens and designed landscape, form an important element of the cultural landscape.
3.10 Providing raw material
Soils provide a direct source of minerals and other resources, such as peat, topsoil, sand and gravel. Peat has been used as a traditional fuel in Scotland since prehistoric times and is also particularly important for the Scottish Whisky industry.
3.11 Providing a platform for buildings and roads.
This function is different from the others so far as once soil is used to fulfil a 'platform role', it loses, to a large extent, its capacity to fulfil its multi-functional role in the environment. The 'platform role' is in most cases connected with soil compaction and sealing (covering the soil with an impermeable surface), thereby reducing or destroying the ability of soils to provide environmental and ecological services. Soil is essentially a non-renewable resource and the consequences of sealing are long term.
3.12 The above analysis sets out the environmental, economic and societal benefits that soils provide and the functions that they fulfil.
Question 3. Do you agree with the analysis of the main soil functions presented here?
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