Subgroup | Series name | Percentage | WRB 2006 link |
---|---|---|---|
8.51 | DOWNHOLLAND | 35% | Clayic Fluvic Mollic Gleysols |
8.52 | EASTVILLE | 20% | Fluvic Calcaric Histic Gleysols |
8.52 | CHATTERIS | 15% | Fluvic Calcaric Mollic Gleysols |
10.24 | ADVENTURERS' | 15% | Drainic Rheic Sapric Histosols |
23 |
Loamy and sandy soils with naturally high groundwater and a peaty surface |
This association on marine alluvium consists of clayey humic alluvial gley soils, Downholland series, clayey and silty calcareous humic alluvial gley soils, Eastville and Chatteris series, and earthy eutro-amorphous peat soils, Adventurers' series. As the original peat cover in the Fens has wasted the association has become extensive in Cambridgeshire, Norfolk and Lincolnshire and occurs also on the Somerset Levels and Moors, notably in the Axe valley. The land is flat but there is often a marked microrelief of low ridges, called rodhams in the Fens, marking the positions of former creeks and giving a complex soil pattern with silty soils on ridges and clayey and peaty soils on intervening ground. The association also includes soil series such as Tanvats, Wisbech, Wallasea, Midelney, Compton, Newchurch, Altcar and Prickwillow, but never all together, there being local differences in the soil pattern.
The composition varies because the various alluvial deposits have different stratigraphical relationships. In Cambridgeshire and Norfolk, the lower Fen Clay occurs at or below sea level but in Lincolnshire it is generally higher, up to 3 m O.D.. Downholland series is generally the most extensive soil but in Norfolk and Cambridgeshire the Downholland and Eastville series are co-dominant. Extremely acid sulphuric humic alluvial gley soils and earthy sulphuric peat soils (Prickwillow series) are common around the margins of the Fen Clay in Cambridgeshire, often where the clay is thin, but are less common in Lincolnshire. Patches of Adventurers' series found in low places in Lincolnshire are less widespread than in Cambridgeshire where the original peat cover was generally thicker. In Lincolnshire the topsoils are often slightly humose because of intensive arable use. In places, especially where the peat fen and upper marsh adjoin, Wallasea soils have developed following further loss of organic matter. Near Lincoln there are some humose clayey over sandy soils fringing the Witham fens. The large creek ridges here carry Chatteris and Wisbech soils. In Cambridgeshire some of the component peat soils are semi-fibrous and belong to Altcar series.
There are about 60 kmĀ² of the association in the Somerset Levels and Moors, mainly in the Axe valley between the Mendips and the Isle of Wedmore, formerly mapped as Allerton series and shallow Godney series peats. Eastville soils are common in which calcareous carbonate concretions are present at shallower depth than in the Downholland soils. The small areas of associated peat are nowadays thinner as a result of recent drainage improvements and only local patches of shallow phase Altcar or Adventurers' soils remain. Clayey riverine alluvium gives Midelney, Wensum or Compton series around the lowland edges or along streams.
Most of these soils are well drained or only occasionally waterlogged (Wetness Class I or II) where water levels are controlled by ditches and pumps. The subsoils are normally very porous as a result of vertical channels created by the former reed vegetation and so respond well to drainage treatments. Apart from potatoes, arable crops only suffer from drought in unusually dry summers. However, where subsoil acidity restricts root growth, crops regularly suffer from summer drought.
In the South West the soils are seasonally waterlogged (Wetness Class IV) and were flooded at times in winter, but pump systems are now used to control water levels and flooding is rare.
Where drained, these soils are easy to work but are easily compacted where they are no longer peaty because of long arable use. The soils are rarely wet provided subsoiling is used to maintain continuous permeability from the plough layer to the porous subsoil. The patchy distribution of peaty, clayey and calcareous silty soils causes difficulty in the timing of field operations and the correct use of fertilizers. Standard applications of nitrogen sometimes cause patchy lodging and differential ripening in cereals on contrasting soils. Specially designed implements or double diggers have been used locally in Cambridgeshire to mix subsoil and topsoil to limit the loss of organic matter and break up acid layers that form barriers to rooting. Wind erosion of the peat soils is a problem in Cambridgeshire and Norfolk. The main crops are cereals, potatoes, sugar beet, peas and field vegetables but poor cereal finishing and weedy crops are common on the component peat soils. With direct drilling, yields of autumn-sown crops are likely to be similar to those from conventional cultivations, but the soils are less suited to those techniques for most spring-sown crops. Manganese deficiency occurs on the peat soils through overliming. In Somerset the land is in permanent grass capable of producing high yields but used mainly as summer pasture because the soils poach easily and are not trafficable when wet.
Note that the yellow shading represents a buffer to highlight the location of very small areas of the association.
South Western Region
Eastern Region
South Western Region
Eastern Region
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 09/12/2024
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