All information Copyright, Cranfield University © 2017

Citation: To use information from this web resource in your work, please cite this as follows:
Cranfield University 2017. The Soils Guide. Available: www.landis.org.uk. Cranfield University, UK. Last accessed 16/12/2017

0541w Newnham

« 0343g Newmarket 2 Associations Soilsguide Home 0551d NEWPORT 1 »

Soil and site characteristics

Well drained reddish coarse and fine loamy soils over gravel, locally deep. Some similar soils affected by groundwater.

Geology

River terrace drift

Cropping and Land Use

Cereals and some fruit; much grassland in the South West.

Component soil series

Subgroup Series name Percentage WRB 2006 link
5.41 NEWNHAM 26% Eutric Endoskeleti-Eutric Cambisols
5.71 HUNTWORTH 24% Chromic Endoskeletic Luvisols
5.43 HOPSFORD 20% Eutric Endogleyic Cambisols

Covers 182 km2 in England and Wales

Soilscapes Classification

6
Freely draining slightly acid loamy soils

Top

0541w Newnham

Detailed Description

The Newnham association includes reddish and occasional brownish, mainly well drained soils in river terrace deposits and associated drift. These versatile loamy soils often rest on gravel at relatively shallow depth and occur on level terraces along the main river valleys in Devon, Somerset, Gloucester, Hereford and Worcester and Powys. The terrace gravels, in the main, composed of siltstones, sandstones and hard quartzite pebbles, have a sandy loam matrix. The association is dominated by the reddish coarse loamy typical brown earths, Newnham series, in weathered non-calcareous gravel. The associated fine loamy Huntworth series and coarse loamy Rushwick series (Palmer 1982) are both typical argillic brown earths developed in the same parent material. Similar deeper but brownish porous soils of the Hopsford series, seasonally affected by high groundwater-tables, are locally important. Most soils are slightly stony in the surface horizon but stoniness increases with depth. Silt contents, approaching 50 per cent in the upper horizons, decline in the gravelly subsoils. About 48 km² are mapped in Hereford and Worcester in the valleys of the Severn, Teme, Lugg and Wye. Along the Wye and upper Teme reddish Newnham soils predominate but the depth to gravel is variable and deeper reddish coarse loamy Oglethorpe soils, formerly Castleton series (Colborne 1981), are common. Further south and east as rainfall declines, the proportion of typical argillic brown earths increases and coarse loamy Rushwick soils resting on non-calcareous gravels dominate in the Teme and Severn valleys around Worcester. Silurian and Devonian limestones occur in the gravels occasionally and the matrix is calcareous in places giving Peaton series (Palmer 1982), especially on low knolls within the river terraces or on the terrace edges. Almost 13 km² are mapped in Powys in the Wye and Usk valleys. The reddish Newnham soils predominate but the depth to gravel is variable and deeper reddish coarse loamy Oglethorpe soils - formerly Castleton series - are common.

Typical brown earths predominate in Devon, whereas typical argillic brown earths are more evident in Somerset between Taunton and Bridgwater, where the association is dominated by Huntworth soils. The Whimple series is included where the terrace gravels thin over Triassic mudstones between the dissected terraces. Along the Severn north-east of Chepstow, Huntworth soils and wetter reddish fine loamy soils, Salwick series, in deeper drift are dominant.

Near Exeter and between Porlock and Watchet, reddish coarse and fine loamy typical brown earths, mainly Newnham and Oglethorpe series, cover flat terraces only a little above the river floodplains. Depth to gravel is variable but it is nearly always below 40 cm and often below 80 cm depth. Wetter soils are confined to narrow patches adjacent to valley sides. Near Honiton the soils are generally deeper than in other parts of the region with the gravel usually below 80 cm depth. Here brownish fine loamy soils, many slightly affected by groundwater, in particular gleyic brown earths of the Hopsford series, are also common. Other soils include well drained fine loamy East Keswick series, coarse loamy Wick series , and coarse loamy Arrow series. In the small patches of Newnham association along the Taw estuary fine loamy typical brown earths over gravel, the Rheidol series predominate, but near Braunton Burrows calcareous sand blown from nearby dunes has produced typical brown calcareous earths over part of the terrace with gleyic brown sands on its western flank.


Soil Water Regime

Newnham and Huntworth soils on permeable gravels are well drained (Wetness Class I). Hopsford soils, although affected by fluctuating groundwater, are relatively porous (Wetness Class I or II depending on provision of underdrainage). The Newnham association occupies level sites and readily accepts winter rainfall, unless structure has been weakened by repeated or ill-timed cultivations. Although roots are able to penetrate deeply all soils are moderately droughty for grass and slightly or moderately droughty for potatoes and these crops benefit from irrigation.

Cropping and Land Use

The well drained coarse loamy soils and level low-lying land encourages cultivation. A field capacity period of less than 150 days and long growing season allows good yields from a wide range of crops. Cereals are widespread although top fruit, soft fruit and potatoes are of local importance in Hereford and Worcester. Cultivations are easy and even in wet years there is some scope for springtime working. Subsoil compaction and subsequent surface wetness become a limitation if the soils are worked too soon after rain. Permeability can be restored easily, however, by subsoiling or deep cultivation. The large sand and silt contents make the soil susceptible to slaking particularly where organic matter is depleted. Seedling emergence is checked if, after sowing, heavy rain is followed by dry weather. Near Worcester strawberries and raspberries are grown for the pick-your-own market. There are orchards of dessert plums, cherries, apples and pears but irrigation is necessary during dry summer spells. There is some horticulture south of Exeter and around other large towns. Grass growth is restricted by droughtiness in most years but there is little risk of poaching these well drained soils, so grassland can be grazed in autumn and spring.

Top

0541w Newnham

Typical Landscapes

Top

All information Copyright, Cranfield University © 2017

Citation: To use information from this web resource in your work, please cite this as follows:
Cranfield University 2017. The Soils Guide. Available: www.landis.org.uk. Cranfield University, UK. Last accessed 16/12/2017