Principles of Soil Science Lab Exercise

Soil Science

• Soil is a dynamic system that forms at the interface of the atmosphere and lithosphere, shaped by climate, living organisms, and parent material over time.
• A soil develops distinct characteristics, making it suitable for specific land uses (e.g., residential, crop production).

History of Soil Science

• V.V. Dokuchaev (1846-1903) is considered the Father of Modern Soil Science.
• He introduced the ABC horizon nomenclature system in his book "Russian Chernozem" (1883).
• H.Jenny (1899-1992) published "Factors of Soil Formation" in 1941, which presented the equation: Soil = f(cl, o, r, p, t,…)

Soil Formation Factors

• Climate (cl)
• Organisms (o)
• Relief (r)
• Parent material (p)
• Time (t)

Soil Survey and Classification

• A systematic examination, description, classification, and mapping of soils in a given area.
• Evaluates and records various properties that determine soil productivity.

Soil Examination Methods

• Fresh roadcuts
• Newly dug pits
• Soil materials collected using a soil auger

Site Characteristics

• Location
• Landform
• Topographic position
• Vegetation
• Land use
• Parent material
• Drainage
• Climate

Soil Profile and Horizons

• Soil profile: a vertical face of the soil, exposing all layers (horizons) from the surface down to the parent material.
• Horizons: horizontal layers of the soil, designated with letters (e.g., O, A, E, B).

Master Horizons

• O Horizon: composed of organic material • Oi: slightly decomposed • Oe: moderately decomposed • Oa: well decomposed

• A Horizon: composed of mineral soil particles, darkened by humus or organic matter • Ap: plowed • Ah: humus

• E Horizon: horizons from which clay, iron, aluminum, or some combination have been leached, leaving a light-colored horizon (bleached horizon) • Typically found in soils developed from granite and sandstones under pine forests in temperate regions • Formed between A and B horizons, zone of "eluviation"

• B Horizon: characterized by the concentration of clay, iron, aluminum, or silica, and evidence of carbonate removal • Bt: clay accumulation • Bw: structure formation • Zone of "illuviation"