2 What is soil?The loose, weathered material on Earth’s surface in which plants can grow.
3 What is the main ingredient? The main ingredient for soil is the solid layer of rock beneath the soil called bedrock.
4 Soil CompositionA mixture of rock particles, minerals, decayed organic materials, water and air.Known as sand, silt, clay and gravel
5 What is humus?Decayed organic material in soil from plant and animal remainsProvides spaces in soil for water and airAlso contains many nutrients that plants need to growOften dark in color
6 Soil Fertility The measure of how well soil supports plant growth Soil rich in humus has a high fertility contentSandy soil has low humus and an low fertility content
7 Soil Texture Depends on the size of soil particles Sand feels coarse and grainyClay feels smooth and silkySilt is dry or moist and stickyClassified by size (smallest to largest)ClaySiltSandGravel
8 What is loam?Soil that is made of equal parts clay, silt and sand and holds air and water
9 Process of Soil Formation Soil forms as rock is broken down by weathering and mixes with other materials on the surfaceSoil is constantly being formed whenever bedrock is being exposedSoil forms into horizons or layers
10 What is a soil horizon?A layer of soil that differs in color and texture from the layers above and below it
11 What are the different soil horizons and what are their characteristics? Horizon A- topsoil- a crumbly, dark brown soil with a mixture of humus, clay, and other materialsHorizon B – subsoil- clay and other particles washed down from A, little humusHorizon C – weathered rock
12 Soil Horizons Horizon A - Topsoil Horizon B - Subsoil Horizon C Bedrock
13 What are soil organisms? These living things make humus and other materials that makes soil fertileThese creatures mix the soil and make spaces for water and air
14 What is litter?The loose layer of dead plant leaves and stems on the soil surface
15 What are decomposers?Organisms that live in soil and turn dead organic material into humusIncludes fungi, bacteria, worms and other small animals or bugsWorms do most of the work, they eat their way through the soil and carry soil between layers, the waste is enriched with nutrients