All information Copyright, Cranfield University © 2018

Citation: To use information from this web resource in your work, please cite this as follows:
Cranfield University 2018. The Soils Guide. Available: www.landis.org.uk. Cranfield University, UK. Last accessed 23/02/2018

1021 TURBARY MOOR

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Soil and site characteristics

Deep earthy peat soils. Groundwater usually controlled by ditches and pumps. Very acid with high groundwater levels where uncultivated. Risk of wind erosion.

Geology

Raised bog peat

Cropping and Land Use

Permanent grassland and deciduous woodland; peat extraction; wetland habitats in Somerset; cereals, sugar beet, potatoes and field vegetables in the Fens.

Component soil series

Subgroup Series name Percentage WRB 2006 link
10.21 TURBARY MOOR 80% Drainic Rheic Sapric Histosols
10.11 LONGMOSS 20% Ombric Fibric Histosols

Covers 155 km2 in England and Wales

Soilscapes Classification

26
Raised bog peat soils

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1021 TURBARY MOOR

Detailed Description

This association of peat soils has as its main constituent the Turbary Moor series which belongs to the earthy oligo-fibrous peat soils and has an earthy topsoil formed in acid cotton-grass peat in which moss remains are subordinate. It is found on lowland raised bog peats, variously modified from their original condition by drainage, peat cutting and reclamation for agriculture, and was mapped in Lancashire as Turbary Moor complex by Hall and Folland (1970). Relatively undisturbed moss peats with high water-tables and raw topsoils are mostly mapped in the Longmoss association but Longmoss series remains as inclusions of raw oligo-fibrous peat soils in this association where cutting has never taken place or was only shallow. Westhay series is present where these moss dominated peats have undergone modest drainage improvements and reclamation to grassland provides conditions in the surface layers conducive to the formation of an earthy topsoil.

Turbary is the ancient right to cut peat for fuel and the name Turbary Moor was formerly used (Avery 1955) for a complex soil map unit on the raised bogs of the Somerset peats where cutting had taken place over several centuries. Similar conditions exist in most peatlands elsewhere but recent expansion of the peat industry has reduced the extent of this old cut-over land, by leaving only the underlying fen peat or removing almost all the peat down to the mineral alluvium substrate. Most of the peatlands are at low elevations, from 3 m below O.D. to 15 m O.D., and are relatively flat. They are typically near coasts where rainfall is light and sunshine plentiful, factors which combine to give a potential for intensive cropping. The height of the water-table depends entirely on the standard of arterial drainage and the local needs for particular agricultural or other use. Reclamation of the Lancashire mosslands has taken place over many years, the earliest schemes often following fuel peat cuttings. The two main methods involved either grazing for several years followed by drainage, reseeding and fertilizing, or the more direct approach of clearing, draining in stages, and planting fertilized pioneer crops such as potatoes. Since reclamation, the land has become high quality ley grassland or more often arable land in rotational crops. The topsoil of well humified black peat with strong granular structure rests abruptly on fibrous, often laminated, peat below. These lower layers contain abundant rope-like remains of cotton-grass, together with light brown fragments of moss and dark twigs from ling.

In Somerset, around Meare, because of the increase in mechanical peat extraction in recent years, the situation is complex and changing. Since the soil surveys of the Glastonbury and Mendip districts the raised bog peats have been so exploited that only about 10 km² remain. In common with Altcar soils, on adjoining fen peat, the acid cotton grass and moss peat soils which survive are in grassland of rather poor quality, usually in fragmented holdings and with very varied groundwater control.

There is one small occurrence in Northern England, on the Lancashire border near Holme, Cumbria. It is 3 km² in extent and includes Burton, Hale and Holme Mosses. The peat has a pH around 6 and is deep, although it has been cut in the past. The land suffers periodically from flooding despite attempts at drainage in past times. There is a patchwork of small fields in rough grazing, with considerable scrub and some woodland remnants. Drainage is by open ditches, which constitute the field boundaries. A comprehensive drainage system, involving pumping, would be necessary before this land could be brought into more intensive use.

In Cambridgeshire raised bog once covered much of the Fenland between Peterborough and Ramsey but most has wasted or been cut away in the past, apart from the 12 km² of the association that remains around Holme Fen. Here some of the raised bog peat is now conserved as woodland. The soils belong almost exclusively to Turbary Moor series, but in the cropped parts repeated liming, marling and application of fertilizer has created some moderately acid soils. The surface of the land is now a little below sea level and between two and four metres of peat remain. The land is divided by a network of ditches connecting to main drainage channels which are pumped. In common with other drained lowland peats the land suffers wastage. The land was once at least 3 m higher than at present. After the systematic drainage of Holme Fen and Whittlesey Mere in the mid 19th century there was an immediate drop in the ground surface caused by shrinkage through loss of water. The peat has since continued to disappear at a steady rate (estimated at 1 cm annually) by oxidation and wind erosion. The latter occurs mainly in dry springs when the ground is relatively bare for long periods, especially where sown with sugar beet or potatoes. Sometimes the crop has to be resown after a blow and filled-in ditches have to be cleared. The first pumps were steam-driven centrifugal pumps which were followed by more effective diesel pumps in the 1920s. An electric pump which can lift water from the now much lowered drains into the embanked arterial system was commissioned in the 1960s. The component soils benefit from pipe drainage which is installed in most of the cultivated land. The older systems are of clay pipes but because of peat wastage these are becoming ineffective and are being replaced by plastic pipe systems.

Soil Water Regime

When improved for arable crops, usually by pumped ditches combined with field drains, Turbary Moor soils are permeable and well drained (Wetness Class I). Like all peats they can hold large amounts of available water and so are non-droughty for all crops.

Cropping and Land Use

In Eastern England the land is largely cultivated apart from the birch woodland of Holme Fen. A wide range of crops can be grown and high yields are obtained. Main crop potatoes, sugar beet and specialized crops such as carrots and celery are common. Cereals, especially wheat, are grown as break crops. There is a long period in autumn for landwork and there is plenty of opportunity for spring cultivations. The soils can be worked during drier spells in most winters. Trials show that better yields are obtained using traditional cultivations than by direct drilling.

In Somerset, agricultural use is subsidiary to peat extraction. In the past, the land was reclaimed after cutting for fuel to become poor quality grassland attached to neighbouring much fragmented farms on nearby fen peat. Traditional farmers rarely recognized the large lime requirement of these acid peat soils. The upper layers of low bulk density tend to dry out even with groundwater at shallow depth. In spite of this, nitrogen released by oxidizing organic matter ensures moderate levels of dry matter production.

The soils are well suited to grassland where artificially drained and suitably managed, varieties used for reseeding should be capable of quick establishment to avoid excessive colonization by weeds and pulling of grass by grazing animals.

With the current growth of peat extraction, some grassland has been lost and there is little incentive to improve the management of the rest while the possibility of peat working remains. Various techniques for reclamation of land from which peat has been completely removed are being tried, which may stimulate improved utilization of the land as a whole.

In Somerset there is no experience of arable cropping on these acid peats. This is in contrast to the local fen peats where pump drainage in recent years has allowed arable crops to be grown on some farms albeit on a small scale. Calculation of droughtiness from profile available water and moisture deficit show both types of peat to be non-droughty for all main crops. Crop losses caused by early autumn frosts were experienced on an ADAS experimental site on fen peat, these were partly attributed to cold air flow from nearby slopes but black surface radiation losses would apply equally to the raised moss peats in arable use. Potassium deficiency is fairly general and there is usually a response by crops to applications of copper.

Raised mosses have long been valued by conservationists for their unique flora and fauna and several reserves have been established. The pressures of peat extraction have affected some sites either by actual destruction or by lowering groundwater levels. The open water left after complete extraction provides valued habitats for birds and water plants and often can be integrated with other uses such as flood water storage and recreational activities.

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1021 TURBARY MOOR

Typical Landscapes

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All information Copyright, Cranfield University © 2018

Citation: To use information from this web resource in your work, please cite this as follows:
Cranfield University 2018. The Soils Guide. Available: www.landis.org.uk. Cranfield University, UK. Last accessed 23/02/2018