About soil

Soil is the top layer of the Earth’s crust, and consists of rock and mineral particles as well as dead, decaying and living organisms of plant and animal origin. It also consists of interconnecting pores containing water and air.

Soil is a finite natural resource which has taken thousands of years to develop. It varies from place to place depending on the particular combination of geology, climate, topography (physical features of an area), vegetation cover, time and human activity. Soils are characterised by the type and arrangement of their horizons (layers) and their associated properties, such as texture, colour and drainage features.

Scotland’s soils have been classified into 25 major soil subgroups, each of which consists of soils with similar type and arrangement of horizons. In addition, more than 1000 individual soil types (series) have been identified, defined by their physical and chemical characteristics and soil forming process.

Scottish soils are relatively young in geological terms, having begun developing around 10,000 to 15,000 years ago, at the end of the last ice age. Mineral soils are predominantly found in the lowlands of Scotland, with freely draining brown earth soils more common in the drier east and podzols (the most common soil type) associated with the more acidic areas. Poorly draining gleys are mainly found in the wetter west and peaty soils are mostly found in the Highlands and Southern Uplands.

Soil is essential as it supports most of the life on Earth, both directly and indirectly. It fulfils seven vital key functions:

• providing the basis for food and biomass production;
• controlling and regulating environmental interactions – regulating water flow and quality;
• storing carbon and maintaining the balance of gases in the air;
• providing valued habitats and sustaining biodiversity;
• providing a platform for buildings and roads;
• providing raw material;
• preserving cultural and archaeological heritage.

Although soil has a degree of resilience to disturbance, it is vulnerable and can be easily damaged or destroyed by human activities. As Scotland’s environmental regulator and adviser to the Scottish Government, we have an important role to play in protecting Scotland’s soils.

We regulate the application of many industrial waste materials to land by ensuring they are only applied where there is agricultural benefit or ecological improvement.

We also provide advice to help improve the way people (land managers and farmers) manage and protect soil, and we promote and encourage research to increase our knowledge on soil. We also have a duty to report on the state of the environment and previously published a report in 2001 on the state of Scotland’s soils, which examined the wide range of pressures that affect soil quality in Scotland. Our forthcoming State of Soils 2011 Report, which has been written in conjunction with partners across Scotland, will serve as an update to this report.