* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Soils of Britain
Survey
Document related concepts
Surface runoff wikipedia , lookup
Crop rotation wikipedia , lookup
Soil food web wikipedia , lookup
Soil compaction (agriculture) wikipedia , lookup
Soil horizon wikipedia , lookup
Agroecology wikipedia , lookup
Human impact on the nitrogen cycle wikipedia , lookup
No-till farming wikipedia , lookup
Soil contamination wikipedia , lookup
Soil microbiology wikipedia , lookup
Terra preta wikipedia , lookup
Transcript
Did you know that, despite our modest land area and limited range of cool, temperate climates, there are over 1,800 British soils types, each with a diversity of profiles. Geologically, Britain has a wide range of rock types and these generate diverse soil parent materials, ranging from porous sands to impermeable clays and from acid to alkaline. This variety increased over the past two million years, when Britain’s climate fluctuated between arctic Ice Ages and warm temperate conditions. Surface materials were moved and sorted by ice, wind and water. This resulted in many mixtures and combinations of soil parent materials from different rock types. Climatic swings also affected the topography and many British landscapes were sculpted by ice and water. The British Society of Soil Science Bullock Building Cranfield University Cranfield Bedfordshire MK43 0AL, UK T: +44 (0)1234 752 983 F: +44 (0)1234 752 970 E: [email protected] W: www.soils.org.uk “There is gradation in soils from warm dry lowlands up to the cooler wetter highlands” “In the lowlands, the Brown Earths, Gleys and the transitions between have simple brown or grey profiles with variable textures, drainage and contents of limestones” “Shallow dark Rendzinas on chalk and limestone hills are moderately productive arable soils” “Artificial drainage of Gleysols and other lowland clays improves their agricultural productivity making them the main arable soils of Britain” 6 “In highland areas, slow decomposition of organic matter and the lack of mixing by worms and other soil animals produce Peats” “Acid sandy parent materials develop brightly coloured Podzol soils” “Podzols and acid Peats have low agricultural productivity, but non-acid Fen Peats are very productive after drainage” www.soils.org.uk S.Hallett, I.Baillie, B.Kerr, L.Deeks, L.Hallett 2011 There is a climatic gradation of soils in Britain from the warm dry lowlands in the south to the cooler, wetter highlands in the north. Within this climatic pattern, soils vary between rock types, and locally within landscapes ranging from well-drained soils on crests and slopes to imperfectly or poorly-drained valley soils. The British soils we have today have also been much modified by agricultural and industrial activities over the centuries. “Varied rocks and Ice Age activity have developed diverse soils in Britain” For the advancement of soil science Soils of Britain Great diversity on a small island www.soil-net.com ® The British Society of Soil Science is a limited company, registered in England and Wales No. 7110309 and a Registered Charity No. 1134456. www.soils.org.uk However, following drainage, non-acid lowland peats can be highly productive and the Fen Peats of Eastern England form some of the most important horticultural soils in Britain supplying many of the market garden crops. Gleysols have impeded drainage, occurring on lower slopes and valleys. They have simple profiles with dark topsoils over wet grey subsoil, often mottled rusty brown. In really wet sites the mottles disappear with depth and the greys become faintly bluish or greenish. These soils often have high clay content. Gleys form where water fills the soil pores and blocks off air flow. The lack of air transforms iron from rusty oxides to paler forms. The rust mottles form in pockets of better aeration. Rendzinas Lowland soils Cambisols, or Brown Earths, are the dominant, well-drained lowland soils, and are also common at lower altitudes in the west. They have simple profiles: dark brown topsoils over lighter brown subsoils. The colouring is due to worms which break up plant litter, dragging it into the soil, thus mixing organic matter down into the profile. Some Cambisols have reddish or yellowish tinges inherited from different source rocks. Textures range from sandy to heavy clays. Clay content usually increases from top- to subsoil. Some Cambisols contain or overlie limestone, others can be acid. Rendzinas are shallow, dark soils that occur on chalk downland and other limestone hills. Limestone dissolves in rainwater and so weathering leaves little material for soil formation. The profile consists of a few decimetres of mixed organic matter, chalk fragments and limited amounts of impurities and windblown imports. The productivity of most Gleys and some Brown Earths with high clay content increases after artificial drainage. The modern agricultural landscape of lowland Britain owes much to land drainage over the past three centuries. Field drainage is an often under-appreciated infrastructural legacy that now needs continued maintenance and improvement. Once drained, many naturally slow-draining Gleys and Brown Field drainage and the use of Lowland soils Use of Peats and Podzols Podzols and most peats make poor agricultural soils. Peats need drainage and lime. Podzols need lime and fertilisers. These soils are therefore mostly used for rough grazing, game rearing and recreation. Podzols are also used widely for coniferous plantations. Brown earths Podzols have highly colour-contrasted soil profiles, from black topsoils through bleached white, with a thin black layer over bright rusty brown or orange, to yellowish brown. Podzols often form in freely drained, sandy acid parent materials. Acids from organic topsoils leach iron from the bleached upper subsoil, redepositing it as a bright rusty lower layer. The dominant features of natural soil formation in lowland soils are mixing by worms and other small soil animals, moderate leaching, variable drainage, and variable contents of chalk and other limestones. Gleys Peats Histosols, such as peats form where slow decomposition and lack of mixing give deep organic layers on top of mineral profiles. The key factor here is waterlogging. In wet areas throughout Britain, including the Fens, this results in basin peat formation. In the wet highlands, peat develops in a wide range of sites and can so ’blanket’ entire landscapes. Podzols Highland soils Cool, wet highland climates affect soil formation by slowing down decomposition of plant litter and organic matter, and by the processes of leaching and acidification. This results in wet soils with dark organic topsoils and low nutrient fertility. Such mountainous regions may also have shallow, rocky soils. Earths can be very productive, representing the main arable soils of Britain. Rendzinas used to be important agricultural soils in prehistoric times but then became neglected as heavier soils became more accessible. Rendzinas were mostly used for grazing sheep, but many were also ploughed for cereal production from the mid 20th century. This was prompted by the needs of domestic food security in World War II. These soils do not need drainage, tending to be droughty, but crops can extract a degree of moisture from the fractured, underlying limestone rock.