All information Copyright, Cranfield University © 2018

Citation: To use information from this web resource in your work, please cite this as follows:
Cranfield University 2018. The Soils Guide. Available: www.landis.org.uk. Cranfield University, UK. Last accessed 19/10/2018

0572i CURTISDEN

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Soil and site characteristics

Silty soils over siltstone with slowly permeable subsoils and slight seasonal waterlogging. Some similar well drained soils. Some well drained coarse loamy soils over sandstone. Slumping locally.

Geology

Cretaceous and Jurassic siltstone and sandstone

Cropping and Land Use

Dairying on permanent and short term grassland; cereals, potatoes, field vegetables and fruit where drier; woodland on slopes.

Component soil series

Subgroup Series name Percentage WRB 2006 link
5.72 CURTISDEN 40% Endostagnic Luvisols
7.11 CRANBROOK 10% Siltic Luvic Stagnosols
7.11 STANWAY 10% Eutric Albic Luvic Stagnosols
5.41 BEARSTED 7% Eutric Cambisols
5.41 ATRIM 7% Siltic Eutric Cambisols

Covers 1581 km2 in England and Wales

Soilscapes Classification

8
Slightly acid loamy and clayey soils with impeded drainage

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0572i CURTISDEN

Detailed Description

This association occurs principally on soft Cretaceous siltstones and sandstones in the High Weald of Kent, Sussex and Surrey and on similar Jurassic rocks in the South West and the Vale of Evesham. In the High Weald the land is hilly and deeply dissected between 45 and 200 m O.D. in a wide belt from Horsham in the west to Hastings in the east. In South West England on the south to north trending outcrop of the Middle and Upper Lias, much of the land is gently rolling but there are steep west-facing scarps. Lithological variation of the bedrock gives a range of soils, in places in complex patterns. The Wealden rocks consist mostly of thinly-bedded fine-grained sandstones and siltstones with some shales, mudstones and occasional thick beds of harder sandstone in a cyclical succession. Lias rocks are similar but there are fewer sandstones and they lack the regular interbedding.

The dominant Curtisden soils are silty stagnogleyic argillic brown earths with associated Cranbrook and Stanway series, typical stagnogley soils, on less permeable strata. The well drained fine silty Atrim and coarse loamy Bearsted soils found on permeable strata or on slopes, are typical brown earths. Inextensive inclusions of Waterstock, Hook, Ludford or Bishampton soils occur in footslope drift in most districts. Brief descriptions of the principal soils are given below.

The association occurs on the sinuous outcrop of the Middle and Upper Lias in Dorset, Somerset, Avon and Gloucestershire. In west Dorset and south Somerset these rocks include the Yeovil and Pennard Sands and have mainly Curtisden soils, with Stanway and fine silty over clayey Martock soils locally. Atrim soils are on well drained sites often on higher ground. Ludford and Bishampton soils are developed in stony drift on footslopes below the Upper Greensand scarps, and wetter Pinder soils occur in thick drift in hollows and around springs, particularly north-west of Crewkerne and west of Beaminster. In Avon and Gloucestershire much of the association is on the Cotswold scarpland, formerly mapped as the Martock and Atrim series. Yeld soils are included locally. Parts of the scarp are landslipped, for instance, around Dundry Hill, Bath and north of Stroud.

The association occurs extensively in the High Weald principally on Tunbridge Wells Sand and Ashdown Beds, but also on sandstones within the Wadhurst Clay north of Hastings. East of Horsham, Cuckfield Stone and Ardingly Sandstone are included, the latter being hard enough locally to give rock outcrops as near Tunbridge Wells. Shallow Curtisden or Bearsted soils are common where thin seams of sandstone or siltstone outcrop forming shoulders on otherwise rounded hills or marking the edge of deeply incised steep-sided valleys. The land was included in the Cranbrook association in their survey of Kent.

Curtisden soils are usually moderately deep and on gentle or moderate slopes. Cranbrook soils, which are locally dominant, occur downslope from the many springs or on spreads of nearly flat land, as around Slaugham. Well drained soils, formerly described as Pembury series, are now grouped with the fine silty Atrim series and the coarse loamy Bearsted series. These are randomly distributed but frequent around Balcombe and Pembury. Podzolized soils are confined to woodland and are not widespread. Deep fine loamy Waterstock or Ludford and fine silty Hook soils, formerly described as Teise or Ladham series, occurs in Head and colluvium which accumulates at the foot of slopes. Aeolian silt is incorporated in places. Conway soils in silty alluvium occupy narrow floodplains. Fine silty or fine loamy over clayey Wickham and Oxpasture soils and similar soils with red-mottled subsoils, occur sporadically on Grinstead and Wadhurst Clay.


Soil Water Regime

Curtisden and Stanway soils have slowly permeable compact subsoils which cause seasonal waterlogging (Wetness Class III and IV respectively) in undrained land. The soils generally respond to underdrainage by a decrease in the duration of waterlogging (to Wetness Class II and III respectively), although in high rainfall districts the response is smaller. Atrim soils are naturally permeable and well drained (Wetness Class I). In winter, most level or gently sloping land is able to absorb only moderate amounts of rain.

All soils have good reserves of available water for crop production, even though rooting depth is limited by unweathered siltstone in some Atrim and Curtisden profiles. In Somerset and Gloucestershire only permanent grass and potatoes are likely to be slightly affected by drought but Stanway soils with less available water are moderately droughty for these crops. Drought risk decreases with increasing rainfall in Dorset, but grass still suffers slightly. Grass and potatoes growing in Cranbrook and Curtisden soils are likely to be moderately affected by drought in the eastern part of the High Weald, but drought risk decreases with increased rainfall further west.

Cropping and Land Use

There are long periods in autumn when Curtisden and Atrim soils can be cultivated but there are fewer suitable days on Stanway and Martock soils. Autumn cultivations are preferable, since opportunities for spring cultivation are limited. The large amounts of silt and fine sand in the soils make them susceptible to capping and there is some erosion on cultivated slopes. Where unlimed the soils are usually acid. Potassium and phosphorus levels are inherently low.

In Dorset there is much ley and permanent grassland, with an emphasis on dairying. In south Somerset with less rainfall, arable cropping is more important and fruit-growing, chiefly apples, is common. In Avon and Gloucestershire the land is mostly farmed in conjunction with the wetter soils of the Martock association. Hence the main land use is dairying on ley grassland, with occasional mixed farms growing cereals. Patches of permanent grass remain on landslipped ground.

There are good soil water reserves and only a small risk of summer drought, so grass yields are potentially large and are enhanced by a flush of growth in early autumn. Where the soils are drained, poaching risk is slight and some winter grazing is possible. In Dorset, however, where the soils are wet because of impeded drainage, the risk of poaching is greater. The poorer drainage and smaller potential yields of Stanway soils make them less suited to grassland use than others in the association.

In the Tenterden district, good conditions for cultivating Curtisden soils occur, on average, on about 75 days during autumn but the period is shorter in wetter localities further west. Cranbrook soils have a more restricted autumn working period, and Atrim and Bearsted soils a less restricted period. Opportunities in spring for landwork are curtailed by a late end to the field capacity period. Because the soils contain large amounts of silt and fine sand they are susceptible to capping and formation of plough pans, leading to increased run-off and to occasional gully erosion on cultivated sites. The land is poorly suited to sequential direct drilling of cereal crops.

In the South East land use is diverse and includes much woodland on steep-sided valleys. Permanent grass is extensive, especially in wet districts and on steep slopes. Mixed farming with cereals and leys occurs widely and orchards and hops are common in west Kent. Potential yields of grass are large and growth can sustain intensive dairying. In dry districts, summer drought limits yield, particularly on Cranbrook soils. Poaching risk is generally slight and allows some winter grazing but there is a greater risk of poaching on Cranbrook soils in wet districts. Grass is often conserved as silage for winter feeding to cattle, and grazing by sheep is common throughout the year. Where unlimed, the soils are usually acid. Potassium and phosphorus levels are inherently low.

Curtisden soils support very productive forest and woodland and there are few limitations to tree growth. A wide range of conifers and many hardwood species, particularly oak, beech and sweet chestnut are grown. The choice of species is more restricted, however, on Cranbrook soils because they are wetter and on shallow Bearsted and Atrim soils.

Wakehurst and Chiddingly Woods are good examples of mixed deciduous woodland characteristic of the valleys of the High Weald. Pedunculate oak with coppiced hazel, hornbeam and sweet chestnut is typical on Curtisden and Cranbrook soils, but Atrim and Bearsted soils often support more open woodland with an acid heath flora of bracken (Pteridium aquilinum), bilberry (Vaccinium myrtillus), honeysuckle (Lonicera periclymenum) and wavy hair grass (Deschampsia flexuosa). Alder and willow occur near springs and seepage lines.

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0572i CURTISDEN

Typical Landscapes

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All information Copyright, Cranfield University © 2018

Citation: To use information from this web resource in your work, please cite this as follows:
Cranfield University 2018. The Soils Guide. Available: www.landis.org.uk. Cranfield University, UK. Last accessed 19/10/2018