Soil Composition and Influencing Factors

• Soil is the thin, uppermost layer of the earth.
• Soil composition is 45% mineral particles, 25% air, 25% water, and 5% humus.
• Mineral particles like sand and clay affect the soil's permeability.
• Air found in soil pores provides oxygen and nitrogen to plants and organisms.
• Water holds the soil together and enables nutrient uptake by plant roots.

Factors Affecting Soil

• Temperature affects how parent rock breaks down; hot climates experience chemical weathering, while cold climates experience freeze-thaw action.
• Highland areas have cold, wet, waterlogged soil with little life and humus.
• Lowland areas have deeper, well-drained soil with more life and humus.
• Time is the most important factor: the longer rock is exposed to weathering, the more it breaks down.

Soil Profile

• A soil profile is a vertical section of soil with layers called horizons.
• The A horizon is topsoil which is loose and crumbly.
• The B horizon is subsoil, containing stones and is protected from weathering.
• The C horizon consists of partially weathered parent rock above the bedrock.

Soils of Ireland

• Brown soil is the most common in Ireland, found in areas with limited rain and deciduous forests like the Midlands.
• Podzol soils are found in highland areas with more rain; they are grey due to hardpan blocking water and nutrients.
• Podzol soils are typically found in coniferous forests and contain little humus.
• Gley soil forms on gently sloping hills and is blue-grey in color.
• Gley soil is very thin, floods easily, and is not very fertile.
• Peaty soil, also called bogland, takes thousands of years to form.
• Peaty soil is dark, heavily waterlogged, and not very fertile.

Explore soil composition, including mineral particles, air, water, and humus. Learn about factors like temperature, altitude, and time that influence soil formation. Understand the soil profile, including topsoil (A horizon) and subsoil (B horizon).