Brown podzolic

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...

s are a subdivision of the

Podzol In soil science, podzols are the typical soils of coniferous or boreal forests and also the typical soils of eucalypt forests and heathlands in southern Australia. In Western Europe, podzols develop on heathland, which is often a construct of ...

ic soils in the British

soil classification Soil classification deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use. Overview Soil classification is a dynamic subject, from the structure of the system, ...

. Although classed with podzols because they have an iron-rich, or spodic horizon, they are, in fact intermediate between podzols and

Brown earth Brown earth is a type of soil. Brown earths are mostly located between 35° and 55° north of the Equator. The largest expanses cover western and central Europe, large areas of western and trans-Uralian Russia, the east coast of America and easte ...

s. They are common on hilly land in western Europe, in climates where

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...

of more than about 900mm exceeds

evapotranspiration Evapotranspiration (ET) is the combined processes by which water moves from the earth’s surface into the atmosphere. It covers both water evaporation (movement of water to the air directly from soil, canopies, and water bodies) and transp ...

for a large part of the year, and summers are relatively cool. The result is that leaching of the soil profile occurs; in which mobile chemicals are washed out of the topsoil, or

A horizon A soil horizon is a layer parallel to the soil surface whose physical, chemical and biological characteristics differ from the layers above and beneath. Horizons are defined in many cases by obvious physical features, mainly colour and texture. ...

, and accumulate lower down, in the

B horizon A soil horizon is a layer parallel to the soil surface whose physical, chemical and biological characteristics differ from the layers above and beneath. Horizons are defined in many cases by obvious physical features, mainly colour and texture. ...

. These soils have large amounts (more than 5%) of organic carbon in the surface horizon, which is therefore dark in colour. In unploughed situations there may be a "mor"

humus In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Lati ...

layer in which the surface organic matter is only weakly mixed with the mineral component. Unlike podzols proper, these soils have no continuous leached E horizon. This is because they are formed on slopes where, over long periods, the topsoil weathered from higher up the slope is continually being carried down the slope by the action of rain, gravity and faunal activity. This means that fresh supplies of iron and aluminium oxides ( sesquioxides) are constantly being provided, and leaching ensures a net accumulation of these compounds in the B horizon, giving an orange-brown "rusty" colour which is very distinctive. The aluminum and

ferric In chemistry, iron(III) refers to the element iron in its +3 oxidation state. In ionic compounds (salts), such an atom may occur as a separate cation (positive ion) denoted by Fe3+. The adjective ferric or the prefix ferri- is often used to sp ...

iron compounds in the subsoil also tend to bind the soil particles together, giving a "pellety" fine structure to the soil, and improving permeability, so that despite being in relatively high rainfall areas, the soils do not have the grey colours or mottles of

gley soil A gleysol is a wetland soil ( hydric soil) that, unless drained, is saturated with groundwater for long enough to develop a characteristic colour pattern. The pattern is essentially made up of reddish, brownish, or yellowish colours at surfaces ...

s. In the

World Reference Base for Soil Resources The World Reference Base for Soil Resources (WRB) is an international soil classification system for naming soils and creating legends for soil maps. The currently valid version is the fourth edition 2022. It is edited by a working group of the In ...

, these soils are called Umbrisols, and the

Soil Atlas of Europe Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...

{{cite book , title = Soil Atlas of Europe , author1=Jones, A. , author2=Montanarella, L. , author3=Jones, R. , publisher = European Soil Bureau Network, European Commission, Soil Atlas of Europe , year = 2005 shows a preponderance of this kind of soil in north-west Spain. There is a tendency for the soils to occur in

ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wor ...

ic areas, where there is abundant rainfall throughout the year, winters are mild and summers relatively cool. Thus they are common in

Ireland Ireland ( ; ga, Éire ; Ulster-Scots: ) is an island in the North Atlantic Ocean, in north-western Europe. It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel. Ireland is the s ...

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to ...

Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...

(where they occupy about 20% of the country) and western England, especially

Devon Devon ( , historically known as Devonshire , ) is a ceremonial and non-metropolitan county in South West England. The most populous settlement in Devon is the city of Plymouth, followed by Devon's county town, the city of Exeter. Devo ...

Cornwall Cornwall (; kw, Kernow ) is a Historic counties of England, historic county and Ceremonial counties of England, ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people ...

and the

Lake District The Lake District, also known as the Lakes or Lakeland, is a mountainous region in North West England. A popular holiday destination, it is famous for its lakes, forests, and mountains (or '' fells''), and its associations with William Wordswor ...

. They also occur in the

Appalachian Mountains The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. The ...

and on the west coast of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

References

Pedology Types of soil