Term | Definition |
what is soil composed of? | Mineral particals (45%)
Air (25%)
Water (25%)
Living organisms (5%) |
Describe mineral matter and it's part in soil composition | Mineral Matter is the main ingredient in the soil. It is made up of rock particles that have been weathered and eroded. It includes stones, sand, silt and clay, and provides the minerals that help the plants to grow. |
Describe air and it's part in soil composition | Air fills the spaces between the particles of rock in the soil. Air contains oxygen and nitrogen, which are vital for plants to grow and for living organisms to survive in the soil. |
Describe water and it's part in soil composition | Water makes up about 25% of soil and helps bind the soil together. In minerals dissolved in water and absorbed through the roots of plants and to help them grow. |
Describe living organisms and it's part in soil composition | Soil is home to many types of living things, such as earthworms and various bacteria, fungi , insects and burrowing animals. These organisms break down the organic matter to form humus, and mix up the soil to make it easier for water and air to pass thro |
Name the factors that influence soil formation | Climate + Parent Material + Living Organisms + Landscape + Vegetation +Time = SOIL |
Describe the O horizon | This layer contains organic matter. Leaves decomposing vegetation are called plant litter and this provides the humus for the soil. |
Describe the A horizon | This is the upper layer of the soil and is called the topsoil. This is where most of the organisms in the soil live. It has a high humus content, it is usually darker than the other layers and is the most fertile part of the soil. |
Describe the B horizon | This layer is called the subsoil. It is lighter in colour than the A horizon because there is less humus here. As it is located closer to the bedrock, it has more stones and is protected from weathering and erosion by the horizon. |
Describe the C horizon | This is the bedrock or parent material. The lower layer consists of solid rock but the upper layer may be broken down into rock particles. |
Name the four soil types in Ireland | • Brown earth soils
• Podzols
• Gley soils
• Peaty soils |
What is leaching? | Leaching occurs when the rain washes minerals down from the A horizon to the B horizon. This makes the soil less fertile |
What is a hardpan? | In places where there is heavy rainfall, the minerals may form a crust called a Hardpan which prevents water sinking through it. |