Review Soil is a mixture of 4 materials: Weathered rock particles (sand, silt, and clay) Organic matter Water Air

Review

Horizon O - organic-mostly dead plant matter. Horizon A - Topsoil. Contains the most organic matter (humus) and is dark in color. Horizon B - Subsoil. The layer under A that contains clay and minerals and is usually brownish or reddish in color. Horizon C - Parent material. The deepest layer of soil. Contains the largest and least weathered rocks. It is usually yellow-brown. Horizon D – Bedrock below soil.

Add To Table of Contents: Soil Worksheet Pg. 70 Soil Properties Pg. 71

Soil Properties Pg. 71

1. Porosity - amount of space between sediments. A. Shape-Rounded particles have greater porosity than angular. POROSITY ROUNDNESS ROUND ANGULAR

B. PACKING- The closer the particles the lower the porosity. UNPACKED PACKED

C. SORTING-The more sorted the higher the porosity. - Same size=sorted. - Different sizes = unsorted (poorly sorted) POROSITY SORTING

Particle Size alone does NOT affect porosity Particle Size alone does NOT affect porosity!!!!! (Shaping, Packing, Sorting does)

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2. Permeability-ability of water to pass through -Tighter packing/smaller particles = less -Looser packing/larger particles = more PERMEABILITY PARTICLE SIZE

Impermeability(not permeable) is due to: A. Tight packing of particles B. Cementing by clay or ice

FINE SAND Moderate drainage PERMEABILITY GRAVEL  Rapid drainage  FINE SAND Moderate drainage  CLAY Slow drainage

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Clay is impermeable – water will not flow through easily

3.Capillarity-water sticking to soil particles and moving up from the water table. (capillary action). - Smaller particles have more capillarity. CAPILLARITY PARTICLE SIZE

4. Infiltration – water soaking into the ground. Permeability Infiltration rate Porosity Infiltration rate Infiltration rate Slope