Subgroup | Series name | Percentage | WRB 2006 link |
---|---|---|---|
5.41 | BEARSTED | 50% | Eutric Cambisols |
5.51 | COTTENHAM | 20% | Eutric Rubic Arenosols |
5.54 | FERNHILL | 10% | Arenic Chromic Luvisols |
5.46 | FLITWICK | 10% | Eutric Gleyic Cambisols |
5.46 | OAKINGTON | 5% | Eutric Endogleyic Cambisols |
6 |
Freely draining slightly acid loamy soils |
This is an inextensive association covering 67 kmĀ² along the Lower Greensand outcrop in Bedfordshire and Cambridgeshire, with a small parcel in Buckinghamshire. Most of the soils are coarse loamy or sandy and overlie sand or sandstone and are well-drained, though some have a high water-table in winter. Between Linslade and Gamlingay the soils are mainly on gently undulating land between 35 and 155 m O.D. but they occasionally occur on steeper slopes. Near Oakington and Ely the soils are on low-lying, very gently sloping ground as in the southern part of the Isle of Ely where they rise to 35 m O.D. Coarse loamy Bearsted series, typical brown earths, occupy about half the land and sandy ferruginous Cottenham series, typical brown sands, a further fifth, both being formed in the Greensand. Flitwick and Oakington series, of coarse and fine loamy texture respectively, both gleyic ferritic brown earths, occur on low ground so are subject to winter waterlogging. Like Cottenham soils, the intermittently occurring Fernhill series, which belongs to the argillic brown sands, is ferruginous but has subsoil horizons enriched with clay. Ludford soils are found where fine loamy drift occurs. The soils at Woburn Experimental Farm, which is on this association, are described fully by Catt et al. (1975, 1977, 1980) who show that the texture of the Cottenham series is closely related to that of the underlying Greensand and that the subsoil is almost free from silt and contains about 10 per cent clay.
Bearsted and Cottenham series occur mainly on crests and slopes of the dissected dipslope of the Lower Greensand in Bedfordshire and south-west Cambridgeshire. Flitwick series, developed in drift, floors the valleys and occurs on footslopes underlain by Jurassic clay. Ludford series is found near patches of chalky till. On valley floors incised into Jurassic clay, there are springs which are surrounded by peat soils locally. On crests and slopes relatively hard sandstone is often near the surface. Between Oakington and Ely, Cottenham series is common and, together with Bearsted soils, caps ridges. Oakington series, occasionally waterlogged in winter, occurs on footslopes and other low ground.
Bearsted series is most common on the scarp in thin cherty Head over Foxmould or over glauconitic stoneless sands. Where the head is thicker on the scarp crest or on the Chert Bed dipslope, Luppitt series predominates. In west Dorset typical brown earths are mixed with typical argillic brown earths of the Ardington series. South-west of Warminster, humo-ferric podzols belonging to the Shirrell Heath series are rather more extensive than in Devon, where these soils were formerly mapped as Telegraph series. In east Devon and south-west Somerset, Hense and Quorndon series have been included in this association where wet flushes on footslopes are too small to separate as the Hense association. Further east these wet soils are replaced by Wickham series where Greensand drift overlies Lias, Oxford or Gault Clay. Around Burbage in the Vale of Pewsey on Chert Beds, stony Luppitt soils are associated with Ardington soils, and wetter soils around springs.
The coarse loamy and sandy soils of Bearsted, Fernhill and Cottenham series are permeable except where arable and well drained (Wetness Class I), but the Flitwick and Oakington soils, because of their low lying position and the presence of impermeable Jurassic clay at shallow depth are waterlogged for short periods in winter (Wetness Class II). Where drains have been installed many are now well drained. The sandy Cottenham and Fernhill soils are moderately droughty for cereals, sugar beet and oilseed rape, moderately to very droughty for potatoes and very droughty for grass as these soils are of low water holding capacity with about 85 mm of water available to the plant in the upper metre. Water holding capacity is related to silt content (Catt et al. 1980) so that the Bearsted series, the most extensive soil, has a moderate water holding capacity and is correspondingly less droughty, being slightly droughty for cereals and sugar beet in the wetter western areas. Flitwick and Oakington series are the least drought-affected soils. On arable land, low in organic matter with a weak structure, the soils slake readily, reducing infiltration and causing run-off and erosion.
These light-textured soils are easily worked, particularly the sandy Cottenham and Fernhill series which dry out quickly after rain. There are ample opportunities for traditional autumn and spring cultivations without structural damage to the soil in normal years, although spring cultivations on the heavier soils may be restricted in the wettest years in the west of the region. A wide range of crops is grown including vegetables, small and top fruit (especially around Cottenham and Wilburton) as well as cereals, potatoes and sugar beet. Irrigation is worthwhile because of the large increase in yields obtained. The soils need regular liming and their nutrient status is poor unless the land is fertilized.
In the south west slope dominates land use on the Greensand scarp, which carries permanent grassland, rough grazing or woodland. Maintenance and improvement of grassland is both troublesome and dangerous, and pastures poach more easily than on gentler slopes. Only where the ground flattens, above the scarp as around Shaftesbury and Warminster, or more locally along its foot, is there scope for more intensive use of the soils, although stones in the Chert Beds can seriously hinder cultivations. Because of the free drainage, poaching risk is small where grassland on this relatively level ground is grazed throughout the growing season, and it will stand reasonable winter stocking. Growth is slightly restricted by droughtiness in most seasons particularly where rainfall is lower, as around Warminster. The scarp soils, with their deep rooting, good natural drainage and substantial moisture reserves, have potential for afforestation, with Douglas fir (Pseudotsuga mensiesii) or, in exposed sites, Western hemlock (Tsuga heterophylla) as productive species. Old woodlands of limited economic value form wooded rims to the valleys and combes dissecting the Greensand country, enhancing the landscape and, with the adjoining wetland of the Hense association, providing an extensive wildlife habitat and attractive sites of high amenity value.
Note that the yellow shading represents a buffer to highlight the location of very small areas of the association.
Eastern Region
Eastern Region
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Cranfield University 2024. The Soils Guide. Available: www.landis.org.uk. Cranfield University, UK. Last accessed 08/12/2024
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