All information Copyright, Cranfield University © 2017

Citation: To use information from this web resource in your work, please cite this as follows:
Cranfield University 2017. The Soils Guide. Available: www.landis.org.uk. Cranfield University, UK. Last accessed 21/10/2017

0220 SALINE 1

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Soil and site characteristics

Soils of variable texture flooded by high tides. Many are soft and unripened, others, often on higher sites or of sandy texture, are firm and ripened. Frequently calcareous.

Geology

Marine alluvium

Cropping and Land Use

Saltmarsh habitats some summer grazing; recreation.

Component soil series

Subgroup Series name Percentage WRB 2006 link
2.2 CY/CZY SALINE 50% Calcaric Epigleyic Fluvisols
8.14 WOLFERTON 25% Endosalic Fluvic Calcaric Gleysols
8.12 FRISKNEY 10% Arenic Calcaric Salic Fluvisols
8.22 BRANCASTER 5% Arenic Salic Fluvisols
2.1 SY SALINE 5% Arenic Salic Fluvisols
8.14 NEWCHURCH 5% Clayic Fluvic Calcaric Gleysols

Covers 310 km2 in England and Wales

Soilscapes Classification

1
Saltmarsh soils

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Detailed Description

Formed under saltmarsh vegetation in marine alluvium of various textures, this association includes ripened as well as unripened soils. It occurs in estuaries and creeks in many places round the coast of England and Wales. Saltmarshes lie above the reach of daily tides but are covered by periodic spring tides. Pioneer plants bind the alluvium and, by checking the flow of water, increase sedimentation. Algae, especially seaweeds, are followed by flowering plants, such as glassworts (Salicornia) and, later, by larger and more efficient silt trappers — cord-grass (Spartina townsendii), herbaceous seablite (Suaeda maritima), sea aster (Aster tripolium) and sea purslane (Halimione portulacoides).

Some marshes become completely colonized by Spartina. Since its appearance in Britain at about the turn of the century this tall vigorous perennial hybrid of S. maritima and S. alterniflora has formed almost pure stands over large areas.Developing saltmarshes differ in maturity from one part to another and different plant communities can occur in distinct zones, approximately parallel to the primary source of sediment.

The highest and most mature parts of former marshes have been periodically enclosed behind earthen embankments, derived from a perimeter ditch or borrow pit. Creeks are commonly filled in, drained into the landward ditch at the new sea wall, or left to provide field boundaries or barriers for livestock. In the widest estuaries, saltmarshes formed over long periods with successive sections reclaimed as silting proceeded. Ultimately many square kilometres have been enclosed and, as in the Humber and Ribble estuaries, successive innings have the same pattern of deposition.

The most extensive soils are saline raw gley soils with an unripened mineral horizon that starts at or within 20 cm of the surface. Particle-size class varies but there is always more than 8 per cent clay. There is often a distinct, humose or peaty topsoil. Some soils of the higher saltings resemble alluvial gley soils but, although ripened, remain highly saline until reclamation and drainage. Occasionally, non-saline, ripened alluvial gley soils are found.

In Cumbria there are saltmarshes beside the Duddon estuary and the Solway Firth. Coarse and fine silty unripened and ripened, frequently saline, profiles predominate. At the head of the Solway Firth, ponded fresh water floods the saltmarsh, and the Rockcliffe and Tanvats and the Wisbech series are locally common. On the North Sea coast the association is confined to Humberside, where it occurs at Patrington Haven on the north bank of the Humber, at the confluence of the Ouse and Trent and on the sea coast at Easington.

Saltings in South West England include clayey raw soils around the mouths of the Parret and Axe, in Somerset, and similar clayey and silty soils near Weymouth and at Poole Harbour, in Dorset. Most are under saltmarsh with some reed beds and Spartina. Those in Dorset are part of a National Nature Reserve and provide a haven for birdlife. There are many smaller unmapped areas of saltings around the coasts of the South West, mostly clayey raw soils but in places on the north coast of the peninsula they are sandy due to the presence of calcareous blown sand.

In Wales the association is most extensive in Carmarthen Bay but also occurs in the Dee, Dovey and several smaller estuaries. It includes most undrained and unprotected coastal marshland above mean high water mark. Land below this mark has not been included. Unripened gley soils occur at the mean high water mark under Spartina and Salicornia and consist of loamy (sandy silt loam to silty clay loam), soft and usually calcareous mud. This passes to a higher level of marsh, often by a small step, to vegetation commonly dominated by sea poa (Puccinellia sp.) with Aster along the creeks. The soils are similarly loamy, the coarser soils being found on creek levees. They are saline, partially ripened and often calcareous. Inland, and again often with a small step, there is a zone of Festuca rubra, and here the soils are fully ripened and often non-calcareous. The highest zone of the marsh is again to landward and under Juncus maritimus; here there is commonly the Tanvats series. The pattern described in the Burry inlet is typical of most saltmarshes..

In Lincolnshire saltmarshes fringe the Wash and are found along the coast between Saltfleetby and Tetney. Most of the marshes are ripened to 20 cm depth, the only unripened soils being in the sparsely vegetated zone near the upper limit of ordinary tides. The soils between Boston and Skegness are mainly calcareous and silty. At Tetney, Grainthorpe and Saltfleet in north Lincolnshire and between Boston and the Norfolk boundary, most of the soils are clayey or fine silty. In Norfolk on the Wash and north Norfolk coast the marshes are mature and are dominantly clayey, calcareous and ripened to 50 cm. There are calcareous sandy gley soils on the landward side of spits. In Suffolk the soils are mainly clayey, but locally fine silty. Near the limit of flooding they resemble Wisbech , Agney, Newchurch or Wallasea series but are saline. There are many small saltmarshes along the indented Essex coastline, notably around Canvey Island in the Thames estuary, north of Mersea island in the Blackwater estuary, in the Colne and Stour estuaries and around Hamford Water. The soils are almost all unripened non-calcareous clays with a mature saltmarsh flora, although thin (15 cm), firmer, ripened topsoils occur locally. The largest stretch of saltmarsh is on the Dengie peninsula east of Tillingham. At the landward edge, deep, partially ripened saline clayey soils overlying sand, similar to Wallasea and Newchurch series, are ready for reclamation.

Most saltmarshes in South East England are in the estuaries of the Thames and Medway and around the Solent. In the Medway, Stoke Saltings consist of numerous tiny vegetated islands within the zone covered by spring tides only. South of the main channel are the larger Burntwick and Deadmans Islands, and Nor, Greenborough, Slayhills and Millfordhope marshes, some with breached sea walls indicating former attempts at reclamation. Raw gley soils consisting of unripened, mainly non-calcareous clayey alluvium, characterize these saltmarshes, although there may be a thin, firmer ripened layer at the surface in places. Such soils are saline precursors of the Wallasea series, which occurs on adjacent reclaimed marsh.

Along the Solent, unripened clayey and silty raw gley soils occur on higher, vegetated parts of marshes but receive additions of sand from nearby sand banks at the low tide limit. The alluvium is more calcareous than in Kent. Marshes in Langstone and Chichester harbours and the Lymington, Pennington and Beaulieu river marshes are not shown on the soil map as they are below high water mark. They are being eroded and are considered to be relic features. In both Kent and Hampshire, many of the saltings and the adjacent tidal flats are nature reserves, largely on account of their value as feeding grounds for birds. Spartina anglica, a vigorous tetraploid of cord-grass (S. townsendii), has colonized many of the Solent marshes.

Soil Water Regime

A dendritic creek system channels much of the tidewater but when creeks overflow, the silt-laden waters are partially checked by the vegetation and coarse textured material is deposited, forming low banks or levees. Finer particles are carried farther and settle later under relatively quiet conditions. The particle-size distribution of the constituent soils depends upon the history of marsh development but they are often finer towards the surface and coarser at depth, since progressively finer sediments accumulate as the age and height of the marsh increase. Variations on this simple pattern are common, partly through disturbance by wave action and burrowing animals. Abrupt changes in texture can follow alterations in creek or river courses.

Cropping and Land Use

Saltmarshes are used for wildfowling and, on the higher, more stable ground, for grazing. They are valued as nature reserves and some are Sites of Special Scientific Interest. There is some conflict of interest because many areas could eventually be embanked, drained and cultivated. Reclamation has gone on for centuries and there is scope for more without undue disturbance of the conservation sites. Except for summer grazing on the higher, more stable ground there is no agricultural use. When reclaimed, however, this land can be amongst the most productive land in the country.

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Typical Landscapes

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All information Copyright, Cranfield University © 2017

Citation: To use information from this web resource in your work, please cite this as follows:
Cranfield University 2017. The Soils Guide. Available: www.landis.org.uk. Cranfield University, UK. Last accessed 21/10/2017