Soil Associations

0571i HARWELL

Soil and site characteristics

Well drained loamy soils over sandstone and some similar soils with slight seasonal waterlogging. Shallow stony soils locally. Some slowly permeable seasonally waterlogged fine loamy or fine silty over clayey soils mainly on scarp slopes. Risk of water erosion.

Geology

Cretaceous and Jurassic sandstone, siltstone and clay

Cropping and Land Use

Cereals and dairying on short term grassland; top fruit, hops and potatoes.

Component soil series

Subgroup	Series name	Percentage	WRB 2006 link
5.71	HARWELL	30%	Haplic Luvisols
5.71	SELBORNE	25%	Siltic Endoleptic Luvisols
7.11	HENDRED	20%	Luvic Stagnosols
7.11	BURITON	15%	Endoskeletic Albic Luvic Stagnosols
3.13	NEWTONDALE	10%	Eutric Leptosols

Covers 133 km² in England and Wales

Soilscapes Classification

6	Freely draining slightly acid loamy soils

0571i HARWELL

Detailed Description

This association consists of fertile, easy working greyish brown and olive coloured soils with a small iron content and large fine sand and silt fractions. They are developed in Corallian sandstones (Arngrove Stone) in east Oxfordshire and in Upper Greensand interbedded fine sandstones, siltstones and clays in south Oxfordshire, Hampshire and the Isle of Wight. The sandstones are referred to as malmstone and in some places include chert. The mineral glauconite is a common constituent and it occurs locally in sufficient quantities to give the soils a greenish colour. In most districts the soils are developed on a small, more or less dissected bench or escarpment near the foot of the chalk, and most delineations include a narrow moderately to steeply sloping scarp face and a broader gentle dipslope. In south and east Oxfordshire, however, the soils are found on gently sloping ridges and in the Vale of Kingsclere they occupy the gently sloping lower land of the vale.

Fine loamy or fine silty over clayey Harwell or fine silty Selborne soils, typical argillic brown earths, are most extensive with shallow loamy Newtondale soils, brown rankers, where hard sandstone occurs at shallow depth, particularly near the crest of the escarpment. The wetter fine loamy or fine silty over clayey Hendred and coarse loamy Buriton series, typical stagnogley soils, are present on scarp and valley slopes and in other places where slowly permeable clayey subsoil horizons or dense malmstone layers occur. There are also inclusions of Bignor, Ardington, Mailing, Rivington, Maplestead and Dundale soils. Soil colour and mottle patterns need careful interpretation in many of these soils. Olive and greyish matrix colours in subsoil layers usually reflect a small iron content and large silica/sesquioxide ratio. Ochreous mottling is often associated with weathering sandstone fragments and does not provide a reliable guide to soil wetness.

In south Oxfordshire, Harwell and Selborne soils are dominant with shallow Newtondale soils confined to a few localities; Hendred soils are most common on scarps and Ardington soils occur in patches. The small area of land in east Oxfordshire has Selborne and Newtondale soils with a few Hendred and Bignor soils. Newtondale soils are widespread in east Hampshire on the higher parts of the dipslope though Selborne and similar coarse loamy soils are dominant. These are outnumbered locally by well drained Rivington and Maplestead soils of comparable texture. Buriton and Bignor soils are common near the village of Selborne and there is a complex pattern of gley soils including Hendred series on the slumped scarp slope. In the Vale of Kingsclere, Selborne soils are associated with small numbers of Newtondale and Bignor soils. Harwell and Mailing soils are co-dominant on the Isle of Wight. Newtondale and Selborne soils are confined to land near the crest of the escarpment where cherty sandstones are formed at shallow depth. Dundale soils occur on shallow valley floors. Buriton and Hendred soils are uncommon.

Soil Water Regime

Harwell, Selborne and Newtondale soils are naturally well drained (Wetness Class I) and, when improved by drainage measures, Buriton and Hendred soils are occasionally or seasonally waterlogged (Wetness Class II or III respectively). Vertical water movement is impeded by slowly permeable fine loamy or clayey subsoils or by underlying sandstone or siltstone. These rocks have few coarse pores and the fissures between rock fragments are commonly filled with illuvial clay. Consequently, in winter, the rock layer becomes saturated and slowly permeable so water moves through the subsoil laterally. The pattern of wet and dry soils on escarpment slopes is complex, especially where slumping has occurred and springs are common. There is little surface run-off. Erosion occurs on capped soils, along wheelings and, where flow is concentrated on slopes, rills are common. Surface ponding is frequent on compacted level ground. Regular subsoiling helps to reduce compaction and promote vertical water movement but pipe drainge systems are sometimes preferred, especially on land where crops are often harvested late in the season or where fruit is grown. Selborne and Hendred soils are slightly more droughty than Harwell soils and grass crops are at greatest risk. Crops growing in shallow Newtondale soils are the most vulnerable to yield reduction because of drought.

Cropping and Land Use

Harwell, Selborne and Newtondale soils present few tillage difficulties and with care can be cultivated soon after rain. Topsoil structure is weak however, especially where the content of organic matter is small. Cultivation of waterlogged soil or traffic by farm implements leads to compaction, reduced infiltration and prolonged surface wetness. If bare soil is exposed to heavy rain, slaking and capping occurs and rill erosion often follows. Hendred and Buriton soils need careful management and timely cultivation. The fine textured, water retentive surface layers of Hendred soils combined with slowly permeable subsoils make spring cultivation risky. Favourable conditions for the tillage of Harwell and Selborne soils are limited in spring during wet years in Hampshire and the Isle of Wight and autumn ploughing is preferable; spring work is less often restricted in the drier climate of Oxfordshire, however. The soils are unsuitable for sequential direct drilling of cereal crops since there is a substantial risk of yield loss.

The fertility of this land has long been recognized and its versatility is evident from the wide range of crops grown. Large reserves of available water and the slow but continuous release of potassium together with skilful management ensure that most crops yield well. Benchmark plot investigations in south Oxfordshire demonstrated the yield potential of Harwell soils for cereals, grass and potatoes though harvesting of potato crops can be difficult in wet autumns. Most land is devoted to cereals but grass is also grown. Harwell soils can sustain high stocking densities and the risk of poaching is negligible; yields are slightly smaller in south Oxfordshire than elsewhere. In the Harwell district of Oxfordshire and near Selborne in Hampshire, apples, pears, raspberries and blackberries are grown; there are also several hop gardens around Alton. Buriton and Hendred soils are much less flexible and cropping is restricted to grass and winter cereals. Some strongly sloping scarp and valley sides are in permanent or rough grassland.

0571i HARWELL

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

Typical Landscapes

South Western Region

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: www.landis.org.uk. Cranfield University, UK. Last accessed 16/04/2024