Soil Groups in Ireland: Distribution and Land Use Potential

1. Leaving Certificate Agricultural Science Soil 5 – Soil Groups

3. The General Soil Map of Ireland • This was first published in 1969, with a second edition in 1980. • 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

5. Soil Groups • 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. • Grey Brown Podzolics: Top quality soil type very desirable. • Brown Earths (acid) :Top quality soil type very desirable • Gleys: Intermediate quality • Podzols: Poor quality

6. Soil Profiles • 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

9. Profile of a Grey Brown Podzolics – top quality A1 Earthworm activity has increased OM causing dark colour (3-6cm) A2 Mature* well drained mineral soil. High C.E.C. – fertile, good friability (5-7cm) B1 Has a slightly darker colour due to translocation of clay fraction. This is a horizon of enrichment. Texture is heavy or blocky. C This is calcareous rock (limestone). It is permeable (porous). Generally there is never a drainage problem.

10. Profile of a Grey Brown Podzolics – top quality *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).

11. Profile of a Brown Earth (Acid) – Top Quality

12. Brown Earths A1 This is a mature well- drained mineral soil – well-aerated sand, silt and clay, friable, good structure, good root penetration (60cm) A2 Accumulation of leached calcium ions C Calcareous parent material –limestone – porous and permeable

13. Profile of a Brown Earth (Acid) – Top Quality • 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.

14. Profile of a Brown Earth (Acid) – Top Quality • 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.

15. Profile of a Gley Soil

16. Profile of a Gley Soil A2 Thin layer of topsoil Accumulation of OM gives darkened colour. B Accumulation 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. C Generally impermeable sandstone rock.

17. Profile of a Gley Soil • 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.

18. Profile of a Gley Soil • 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)

19. Profile of a Podzol soil – very poor

20. Profile of a Podzol soil – very poor O A 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. B2 A very poor subsoil – very strong Bir Impermeable iron pan – behaves like a perched water table C Generally an acid rock. Typical example – old red sandstone.

21. Profile of a Podzol soil – very poor • 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.

22. Profile of a Podzol soil – very poor • 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.