How can we define soil with what we know? How Soil Forms How can we define soil with what we know?

What is Soil? Loose weathered material Found on the Earth’s surface Plants use to grow

What is Bedrock? Solid layer of rock Usually beneath soil When weathered becomes soil

What makes up soil? Rock particles from weathered bedrock Minerals Water Air Decayed organic material

What makes soil good for growing plants? The Humus: dark in color Creates space for Air and Water Contains nutrients Phosphorus, Nitrogen Sulfur Potassium Fertile soil is high in humus

What makes soil good for growing plants? The Texture: size of soil particles Clay is smooth and silky Heavy High water content Sandy is coarse and grainy Light Low water content Fertile soil has equal mixtures of particles: Loam

Why? How does soil form? From weathering and mixing Layers called horizons Soil is made up of 4 horizons Warm, rainy climate develop soil faster than cold, dry climates Why?

Does everyone have the same soil? NO…..Why? There are different types of soil depending on …. Climate Plants Soil composition

How does climate affect soil? Cold climates Slow soil formation Thin topsoil Hot climates Fast soil formation Rainfall and wind erode soil away Moderate climates Thickest fertile soil

How do plants affect soil? Plants can grow and die creating humus High vegetation that is NOT removed is high in fertility

How does composition affect soil? Particle size determines Vegetation Water content

How do living organisms affect soil? Some organisms mix the soil Some organisms aerate the soil Make space for air Decomposers make humus

Decomposers Chemically breakdown dead organic material Fungi, worms, bacteria…. Create the humus

Burrowing animals Aerate Make space for water Mix soil Provide nutrients through waste