Soils & Biology

Soil

Soil isn’t dirt, but the accumulation of decayed material over time

Soil is a Fundamental Part of the Ecosystem The living systems above and below the ground are based on the properties of the soil.

The Study of Soil is called Pedology Soil—a natural body of solids, liquid, & gases, with horizons (layers) & the ability to support plants color texture structure roots pores other features

Composition of Soil by Volume Ideal Fertile Soil Mineral 45% Organic Matter 5% Ideal Fertile Soil Water 25% Air 25%

Classification Systems Of Soil Texture Criterion: diameter of soil particles Soil Texture: gravel >2 mm sand 0.05~2 mm silt 0.002~0.05 mm clay < 0.002 mm

Soils Perform Several Vital Functions Sustaining plant and animal life below and above the surface Regulating and partitioning water and solute flow Filtering, buffering, degrading, immobilizing, and detoxifying Storing and cycling nutrients Providing support to structures

Soils Also Have Scientific Names Like plants and animals, soils are classified The system is called Soil Taxonomy The highest level is the soil order (12) The lowest level is the soil series, often a place name

Soil Studies Include Other Fields Science ecology, biology, chemistry Social Studies world trade, land use Mathematics soil loss over one hectare History US settlement, dust bowl Art soil crayons, acrylic paints

Soil Assessment is Also Important to Minimize Risk

Soils Are Alive Organism Types Roles & Benefits bacteria decomposition fungi protozoa nematodes arthropods earthworms Roles & Benefits decomposition release nutrients create pores stabilize soils

Organic Matter microorganism soil animal organic manure

Soil pH Value The best pH value for plants is 6.5 climate: high temperatures and humidity change pH microorganisms: bacteria environment: acid rain

Soil Tests for Quality: physical, chemical, & biological

Physical Tests - Soil Density & Texture Fill a graduated cylinder with ¾ water Add 2-3 teaspoons of soil. Shake well. Allow to settle, and measure the relative percentages of each level - look at particle size differences – sand, silt, and clay layers.

Permeability Assemble filter paper, funnel, and beaker. Add two teaspoons of dry soil. A 25-50 ml of water & start timer. Record time elapsed when water stops dripping

Other Laboratory Tests Include Checks For Soil Nutrients (N, P, K) and pH.

Most kits based on simple extraction methods, combined with color charts for interpretation. pH Nitrogen (NO3) Phosphorus Potassium

All Right, Lets Play in the Dirt!