Soil Site Reporter

Soil Associations

0572k BIGNOR

Soil and site characteristics
Fine loamy soils over sandstone with slowly permeable subsoils and slight seasonal waterlogging. Some slowly permeable seasonally waterlogged coarse loamy soils and fine loamy and fine silty well drained soils over sandstone. Soils shallow to sandstone in places. Landslips and associated irregular terrain locally.

Cretaceous sandstone
Cropping and Land Use
Cereals and short term grassland with dairying.

Component soil series

Subgroup Series name Percentage WRB 2006 link
5.72 BIGNOR 30% Endostagnic Luvisols
7.11 BURITON 20% Endoskeletic Albic Luvic Stagnosols
5.71 SELBORNE 15% Siltic Endoleptic Luvisols
5.71 HARWELL 15% Haplic Luvisols
3.13 NEWTONDALE 10% Eutric Leptosols
Covers 82 km2 in England and Wales

Soilscapes Classification
Slightly acid loamy and clayey soils with impeded drainage

Alert ! - capping silts read the alert
Alert ! - slowly permeable soils with seasonal wetness read the alert

0572k BIGNOR

Detailed Description

Fertile, loamy grey siliceous soils, mostly with impeded drainage, overlying Cretaceous sandstone or chert form this association which occurs on bench-like features seldom more than 2 km wide associated with the Upper Greensand in Buckinghamshire, Oxfordshire, Hampshire and West Sussex. It occurs also north of Reigate in Surrey, and in an area much affected by landslipping along the south coast of the Isle of Wight.

The greyish soils, which are developed in iron-deficient material largely derived from Upper Greensand, have a large fine sand and silt content and often contain small amounts of the potassium-rich mineral, glauconite. The underlying sandstones, locally known as malmstone, are calcareous in places, particularly in east Oxfordshire and Buckinghamshire. The soils usually pass downwards to solid rock through a zone of weathered, tabular sandstone or siltstone. Most land is gently or moderately sloping. In places there are low escarpments with steeper slopes, and steep-sided re-entrant valley heads where springs are active. Locally, landslipped ground has irregular microrelief fringed by steep slopes.

Bignor soils are fine loamy grey siliceous stagnogleyic argillic brown earths, though topsoils are often coarse loamy. Hard rock occurs at moderate depth. Buriton soils are fine loamy typical stagnogley soils with ochreous mottled subsurface horizons and rock at moderate depth. Selborne soils are fine silty grey siliceous typical argillic brown earths over rock at moderate depth, and Harwell soils are similar, but fine silty or fine loamy over clayey passing to rock. Newtondale soils are loamy brown rankers with rock at shallow depth.

Soil distribution is broadly similar everywhere with Bignor, Buriton, Selborne and Harwell soils on level and gently sloping land, and shallow Newtondale soils mainly developed on the crests of escarpment and around valley heads. In Buckinghamshire and south Oxfordshire, Selborne and Harwell are the most widespread associate soils. Calcareous clayey Evesham soils occur where narrow strips of very thin Head overlie clayey strata. The area south-west of Stoke Mandeville was previously mapped as Harwell complex and includes clayey and glauconitic soils as well as greyish loamy soils with ochreous mottles in the deep subsoil formerly described as Harwell series.

Soils on the bench to the north of the South Downs escarpment between Petersfield and Bury are predominantly loamy, and Bignor soils are usually dominant. Locally, however, Buriton soils are dominant, as near Buriton village. Selborne soils are particularly common near Elsted and in other places where the Upper Greensand outcrop is wider than usual. Shallow Newtondale soils sometimes occur on low summits on the Upper Greensand dipslope. Clayey Evesham soils are sporadic but usually restricted to a narrow zone nearest to the chalk escarpment where they are locally associated with green, calcareous, very glauconitic soils developed in the basal beds of the Lower Chalk.

The soil pattern on landslipped ground near Ventnor on the Isle of Wight is complex and unpredictable. Most soils are developed in Upper Greensand material of broken sandstone and chert in a loamy matrix. Bignor and similar silty soils are the most widespread with associated Selborne, Newtondale and Harwell soils, and fine loamy over clayey Wickham soils on footslopes where the disturbed Gault Clay is near the surface.

Soil Water Regime

Slowly permeable tabular sandstone, siltstone or chert, the fissures commonly filled with illuvial clay, impedes profile drainage in Bignor and Buriton series, and causes periodic winter waterlogging (Wetness Class II or III) in most districts. Some field drains are installed in particularly wet patches, but drainage improvements can be expensive where rock has to be excavated before pipes are laid. Selborne, Harwell and Newtondale soils are well drained (Wetness Class I). Most excess winter rain is absorbed but run-off occurs after heavy rainfall.

The principal soils hold large amounts of available water but arable crops in Bignor and Buriton soils are likely to suffer slightly from drought everywhere in most years and grass production is restricted. Harwell and Selborne soils sustain arable crops well in Hampshire and the Isle of Wight, but there are slight reductions in yield in Oxfordshire and Buckinghamshire. Newtondale soils are not normally ploughed and grass wilts badly in summer.

Cropping and Land Use

The main soils are moderately easy to cultivate and there are plenty of opportunities for autumn tillage. The number of suitable days for work on the land in spring is limited, however, and in wet districts there may be few opportunities on Bignor and Buriton soils. Timeliness is particularly important to avoid damaging the weak topsoil structure. Fine seed beds are liable to slake and cap after heavy rain; this leads to extensive rill and sheet erosion even on slight slopes. Newtondale soils are commonly less than 30 cm deep, so where cultivated they are usually ploughed shallowly to avoid excessive implement wear.

Arable farming with short-term grass leys in the rotation is widespread; most farms carry cereal and dairy or beef enterprises but landslipped areas with irregular relief are mainly grassland for cattle. Grass yields are reduced by summer drought but poaching risk is negligible except in wet districts, for example, West Sussex, where there is a significant risk of damage to swards by trampling. Potatoes and brassica crops are also grown in some southern districts. The soils can be slightly acid and occasional liming is needed in some fields. Large amounts of available potassium from weathering glauconite are found in Harwell soils, and potassium fertilizer is rarely required for crops on any of the soils. Uptake of magnesium can be reduced where there are high levels of available potassium in the soil.

0572k BIGNOR

Distribution Map

Note that the yellow shading represents a buffer to highlight the location of very small areas of the association.

Keys to component soil series

South Eastern Region

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Citation: To use information from this web resource in your work, please cite this as follows:
Cranfield University 2024. The Soils Guide. Available: Cranfield University, UK. Last accessed 16/07/2024

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