6 February 2014
What is Soil?
As gardeners we are all interested in the soil that is in our garden or allotment, but what is soil and where does it come from?
Soil is the thin outermost layer of the Earth's crust, and is made up of mineral particles derived from underlying geological materials, organic matter, organisms, water and air.
Soil thickness in England varies from a few centimetres to over a metre, and represent about 10,000 years of natural ecological processes and human input.
It is condidered to be a non-renewable resource because it can't be re-created except within the context of geological timescales.
The effect of the underlying rock and drainage on soils is shown in the wide variety of soil types in England, ranging from chalky to sandy. Soil types frequently change over short distances because of complex interactions between landform, underlying geology, climate and land use - both current and historic.
Soil in England is classified into 10 major groups, accommodating nearly 700 soil types, which are grouped into around 300 associations which reflect the varied geology of the parent rock. These have been split into 27 classifications of what are known as 'Soilscapes', which group soils according to similar basic properties and link this to information on habitats, fertility and land use.
Soil types are also used in the Agricultural Land Classification system, which is used for defining the agricultural potential of land, and which is used as part of the land use planning process.
Soil is the major medium in which plants grow and it also provides a habitat for animals and various micro-organisms. Fertile soil is essential for the production of food, timber and fibre, which are all essential requirements for human existence and for providing economic prosperity.
The main pressures on our soils include erosion, compaction, organic matter decline and the effects of development, such as paving or concreting over, pollution and loss of biodiversity.
Although little statutory protection exists specifically for England's soil, other legislation such as that covering the prevention of pollution and contamination, and for land use planning provides indirect protection.