Presentation on theme: "Soil 5 – Soil Groups. This was first published in 1969, with a second edition in 1980. These show the distribution of the major soil groups throughout."— Presentation transcript:
Soil 5 – Soil Groups
This was first published in 1969, with a second edition in These show the distribution of the major soil groups throughout Ireland (and each county also) as well as a discussion on their land use potential. The major soil groups a. The Podzols b. Brown Podzolics c. Grey – brown Podzolics d. Brown Earths e. Gleys f. Rendzinas g. Lithosols h. Blanket peats i. Basin Peats
Because of the huge variety of rock types in Ireland there is a huge variety of soil types. The ordinance survey of Ireland has classified ~15 great groups. Four of these are of agricultural importance. 1. Grey Brown Podzolics: Top quality soil type very desirable. 2. Brown Earths (acid):Top quality soil type very desirable 3. Gleys: Intermediate quality 4. Podzols: Poor quality
These are gotten by digging down vertically into a soil to its parent rock and looking face on at the different layers. Profiles using the colour, texture and depth of a soil tell us all the properties of that particular soil. Horizon (Peat) only appears in Podzol. It is made up of Organic Matter. A Horizon – Topsoil B Horizon – Subsoil C Horizon – Parent Rock
A1Earthworm activity has increased OM causing dark colour (3-6cm) A2Mature* well drained mineral soil. High C.E.C. – fertile, good friability (5-7cm) B1Has a slightly darker colour due to translocation of clay fraction. This is a horizon of enrichment. Texture is heavy or blocky. CThis is calcareous rock (limestone). It is permeable (porous). Generally there is never a drainage problem.
*Maturity –relatively stone free. This soil is used extensively for tillage (malting barley). Most crops are grown under contract for the 2 major breweries (Guinness and Murphy’s).
A1This is a mature well- drained mineral soil – well-aerated sand, silt and clay, friable, good structure, good root penetration (60cm) A2Accumulation of leached calcium ions CCalcareous parent material –limestone – porous and permeable
These soils are mature, well drained mineral soils. They have not suffered from serious cases of leaching (loss of minerals) They have a uniform profile (i.e. No distinct horizons or layers) The Brown Earths in Ireland are mainly found in areas where the underlying rock is acidic, and therefore the soil is acidic.
With regular liming and fertilising the soils can be quite a productive soil. Brown earth soils have an extensive use range, however they are used mainly for grazing. They are the soils of the Golden Vale – East Limerick, South Tipperary, Waterford, and North and West Cork, and are all excellent producers of grass for the liquid milk market.
A2Thin layer of topsoil Accumulation of OM gives darkened colour. BAccumulation of clay particles. Blue-grey in colour and has mottles of Fe. Leaching is not a feature. Texture is heavy due to capillary water trapped by clay particles – structure less. CGenerally impermeable sandstone rock.
Gley soils form on areas of rolling lowland or gentle sloping hillsides. They suffer from frequent water logging (West of Ireland 205 rain days annually). They develop of impermeable parent rock and suffer because of excess run off from higher ground. Gleys have a limited use range.
They are confined mainly to summer grazing. Stock will have to be removed during the winter to prevent poaching. However with careful draining and liming the potential of this land is hugely increased e.g. mole drains (15cm deep)
OA layer of organic matter. If it exceeds 30 cm it is referred to as a blanket bog. Sphagnum moss grows here (can absorb ~10X its own weight in water). Here there are anaerobic conditions. B2A very poor subsoil – very strong BirImpermeable iron pan – behaves like a perched water table CGenerally an acid rock. Typical example – old red sandstone.
If water logging or flooding occur, then little or no oxygen will be available and organic matter will eventually form an O Horizon. This is the first stage of a formation of a peat and the soil is now known as a Peaty Podzol. When the O Horizon becomes deeper than 30 cm, then the soil is no longer podzol, but is now a blanket peat.
Podzols are not very useful as tillage soils, or for grazing. This is due to their poor drainage and poor root penetration. It has an extremely limited use range. It is confined almost exclusively to forestry (conservation). Where it is used for agriculture – commonage – but they suffer from severe leaching when overgrazed.