Soil Site Reporter

Soil Associations

0313b POWYS

Soil and site characteristics
Shallow well drained loamy soils over rock. Many steep slopes with some gently sloping interfluves. Bare rock locally.

Palaeozoic slaty mudstone and siltstone
Cropping and Land Use
Permanent and short term grassland; stock rearing in uplands, dairying in moist lowlands; some cereals in Devon and Cornwall.

Component soil series

Subgroup Series name Percentage WRB 2006 link
3.13 POWYS 60% Umbric Leptosols
5.41 DENBIGH 30% Eutric Endoleptic Cambisols
Covers 257 km2 in England and Wales

Soilscapes Classification
Freely draining acid loamy soils over rock

0313b POWYS

Detailed Description

Locally significant on slaty Devonian rocks in South West England, particularly in Cornwall, the Powys association is also found on similar Silurian rocks in south Cumbria and Warwickshire. The soils are usually shallow and well drained with exposed bedrock in places. Loamy brown rankers of the Powys series predominate with fine loamy typical brown earths of the Denbigh series the main associate soils. There are smaller inclusions of fine loamy typical brown podzolic soils of the Manod series and on igneous rocks loamy brown podzolic soils of the Malvern series and loamy brown rankers of the Dunwell series.

In Devon and Cornwall the association generally occurs in strongly dissected coastal country on steep slopes and ridge crests, though near Wadebridge the land is less steep. Shallow Denbigh soils with very stony subsoils and Manod soils are commonly found on steep slopes. Dunwell series marks small outcrops of dolerite, which often form low knolls. Soils are locally reddened over the Staddon Grits near Plymouth. Wetter soils of the Ivybridge and Yeollandpark series occupy occasional footslope and flush sites.

In south Cumbria the association is scattered between the Duddon estuary and Kendal. The land was mapped within the Grizedale and Lowick associations by Hall and Folland (1970), who described it as "craggy ground with sporadic rock outcrops interspersed with undulating moraines, hollows and marshy channels". Manod soils occur on steep slopes and rock exposures are common.

Soil Water Regime

The soils are well drained (Wetness Class I) and readily absorb winter rain. Crops on the shallow Powys soils are susceptible to drought though the associated soils have larger moisture reserves.

Cropping and Land Use

Apart from the steep slopes, the main limitation on cropping in the South West is droughtiness, which affects grass more seriously than cereals. Much of the land south of the Camel estuary around Wadebridge and Padstow is used for cereal growing. This concentration of arable farming in north Cornwall reflects the droughtiness and unsuitability of the soils for grassland as much as intrinsically favourable arable conditions. Wetness in spring favours autumn cultivations and, the chief crop, winter barley, benefits from high sunshine values near the coast and relatively low rainfall. Much of the land is exposed to salt-laden westerly winds though salt damage is apparent only one or two fields in from the cliff edge. The large population of rabbits, which inhabit the cliffs, cause much damage to nearby crops and are difficult to control. Near Plymouth some larger farms grow cereals on Powys soils, notably on exposed sites along the coast east of the Yealm Estuary and in the more sheltered broken country around St Germans. Elsewhere much land is under permanent pasture, production from which is restricted by limited soil moisture reserves which are insufficient to sustain growth through dry summer periods. There is, however, little risk of poaching and farm operations can be carried out well into the autumnin most years. Temperatures are sufficiently high for grass to grow in both early and late season. Much steep, and sometimes rocky land is in rough grazing because of difficulties in management. Some slopes have deciduous oak woodland or scrub partially replaced by conifers.

In Cumbria high rainfall offsets the small available water capacity of these soils, which are mostly under permanent grassland. Despite good trafficability, low poaching risk and adequate soil water, a grazing season of less than 140 days and a prolonged field capacity period combine to render the land suitable only for seasonal pasture. Where rockiness and steep slopes hamper mechanized improvement, oak woodland and commercial forestry are found, though forestry. operations are difficult on the most rocky land. Grizedale Forest and nearby plantations contain Scots pine on Powys soils, and Sitka spruce, Japanese larch and Douglas fir on Denbigh soils, where there is also much oak. Hand planting is necessary and phosphorus fertilizer is added to aid establishment on the shallowest soils.

0313b POWYS

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 Western Region

Northern Region

Typical Landscapes

South Western Region

All information Copyright, Cranfield University © 2024

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 15/07/2024

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