Situated in central Ireland, the landscape of Co Offaly is quite varied. The flat floodplain of the River Shannon is in stark contrast to the mountainous region of the Slieve Blooms in the southwest. Outside of these extremes, the county varies, including a rolling to gently undulating landscape. Much of the landscape is characterised by lowlands composed of limestone glacial till.

A central tract, running from Birr to Tullamore, is typified by luvisols (downward clay movement), water-affected soils, basin peats and brown earths (free-draining) associated with eskers. The eskers were formed by glacial melt waters and are excavated for construction materials.

To the east of Tullamore, some of the soils are wetter and basin peat is more commonly found. In general, basin peat is a feature that is common in the midlands of Ireland and is readily found throughout this county.

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Industrial peat

The west and the east of the county have lowland raised bogs, some of which is used for industrial peat. The Slieve Bloom Mountains are comprised of upland sandstone and shale/slate bedrock. The county is naturally drained by the three main rivers and their tributaries, the Shannon, the Barrow and the Boyne.

Luvisols are the most prevalent soil types found in Co Offaly. These are soils in which clay material from the topsoil has moved down the soil profile and gets deposited further down in the subsoil.

These are very good agricultural soils owing to their good nutrient retention associated with their higher clay content. However, the increase in clay in the subsoil can slow down the movement of water through the soil and as a result, these soils can be moderately or imperfectly draining, depending on the overall texture of the soil. The most commonly found are the ‘Elton’ series (found in association 1000a and 1000c led by subgroup 1000). These soils have good moisture-holding capacity, are very productive and have a wide use-range, including grazing and tillage.

Prone to compaction

While these are good soils, they can have weak structure and could be prone to compaction or poaching if stocked during wetter periods.

Alluvial soils are the second most commonly found soil in the county and can be found in the flood plains of the rivers and lakes.

Due to their location, these soils are frequently flooded and can be waterlogged for prolonged periods of the year. Each time the river floods, a new layer of soil or sediment is added to the surface, adding distinct layers of soil material.

The third most prevalent soils in Offaly are calcareous brown earths, all of which are the ‘Baggotstown’ series (found in association 1150a led by subgroup 1150). This series was first mapped in County Limerick.

Here, they are found on gently undulating terrain and are predominantly of limestone origin and are considered free-draining. These soils have a good use-range and can be used for tillage or can be grazed early and late in the season without a serious risk of poaching by livestock.