Add To Table of Contents: Soil Lab Pg. 50 Soil Properties Pg. 51

Review

Review-What are the Soil Horizons? 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 - The deepest layer of soil. Contains the largest and least weathered rocks. It is usually yellow-brown. Horizon D – Bedrock below soil.

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

Soil Properties Pg. 51

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)

Which column has the least porosity? 1 2 3 4 1

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

Which has the least permeability? 1 2 3 4

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

Honors Lab Activity