Soil Associations

0861a Isleham 1

Soil and site characteristics

Deep permeable sandy soils with humose or peaty surface horizon affected by groundwater. Some deep acid peat soils.

Geology

Sandy drift

Cropping and Land Use

Wet lowland heath and bog habitats, some coniferous woodland.

Component soil series

Subgroup	Series name	Percentage	WRB 2006 link
8.61	ISLEHAM	60%	Arenic Mollic Gleysols
10.13	CROWDY	20%	Ombric Sapric Histosols
6.41	SOLLOM	20%	Endogleyic Albic Carbic Podzols

Covers 42 km² in England and Wales

Soilscapes Classification

23	Loamy and sandy soils with naturally high groundwater and a peaty surface

0861a Isleham 1

Detailed Description

This association is found in valley bottoms in the Tertiary basin of Dorset and west Hampshire. The soils are developed in or over permeable sandy, variably stony drift derived from nearby sandy Bagshot Beds and due to high groundwater, are waterlogged for long periods and support much boggy vegetation. The main soils are deep sandy Isleham series, typical humic sandy gley soils with peaty or humose topsoils, acid peats of the Crowdy series, raw oligo-amorphous peat soils, and sandy typical gley podzols of the Sollom series. In the bogs, up to 1 m of acid amorphous peat overlies sandy and clayey drift. Fringing the peat there are Isleham, Sollom and sometimes typical sandy gley Blackwood soils. The association occurs mainly around springs and along many of the small streams draining the Bagshot Beds. Accompanying the main soils there are podzols on low knolls and gentle slopes, including well drained, sandy stoneless Leziate and Shirrell Heathsoils on in situ Bagshot sands and similar but stony Redlodge soils in local sandy drift. Where this sandy drift overlies pipe-clay bands in the Bagshot Beds there are sandy over loamy Holidays Hill soils and similar sandy over clayey stagnogley podzols. Isleham, Sollom and Blackwood soils usually dominate with peat soils restricted to the wettest sites. In the broader depressions are extensive stony sandy and loamy terrace deposits with very stony Isleham and Blackwood soils.

The small area of land in South East England is centred on Cranes Moor on the western edge of the New Forest. Acid peat of the Crowdy series occupies the valley bottom and less wet Isleham and Sollom soils border the peat deposits on flat or gentle slopes where sandy drift has accumulated. On small knolls and gentle slopes well drained sandy stoneless Shirrell Heath podzols occur on Barton Sands.

Soil Water Regime

The main soils are affected by high groundwater throughout much of the year. Crowdy soils are perennially waterlogged (Wetness Class VI) whilst Isleham and Sollom soils are waterlogged for somewhat shorter periods (Wetness Class V).

Cropping and Land Use

These wet very acid soils, with phosphorus and potassium reserves very low, are not much used for agriculture and they have little potential. Where they have been afforested growth of Scots and Corsican pines is poor because of wetness and paucity of plant nutrients. Lodgepole pine grows better particularly with additions of phosphorus fertilizer. The peats are valued as examples of lowland acid bogs and several are designated as National Nature Reserves. Hartland Moor carries some of the finest Dorset Heath (Erica ciliaris) in Britain and a range of hybrids between this species and cross leaved heath (Erica tetralix). Morden Bog has an outstanding insect fauna and Studland Heath is also valued ecologically.

Cranes Moor is ecologically the most outstanding mire system of the New Forest, containing both mesotrophic and more acidic bog with a variety of plant species. Here the peat is over 1 m thick and pollen analysis has shown that its formation began in the late Devensian. Wet heathland occurs near the edge of the mire, but there is a mosaic of bog vegetation communities over the deep peat. Bog mosses (Sphagnum spp) are widespread with abundant purple moor-grass (Molinia caerulea), bog asphodel (Narthecium ossifragum), cotton-grass (Eriophorum angustifolium) and tussocky Molinia-Myrica gale (bog myrtle) communities.

0861a Isleham 1

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

Typical Landscapes

South Western 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 08/12/2024