APBI 200 Lecture Notes - Lecture 2: Soil Texture, Pedogenesis, Soil Horizon
Document Summary
Horticulturists: soil is the medium in which plant roots grow or can grow. Engineers: unconsolidated mineral and organic material on the earth"s surface, down to the bedrock. Soil pedon: a 3-dimensional unit that has full rang properties of a particular soil, usually 1-2 m deep with a surface area of 1-10 m^2. Soil profile: a 2-dimensional, vertical section of the soil from the surface through all its horizons (including c horizon) Mineral vs. organic soil: mineral contains <30% of organic matter by weight; but in most cases they contain 1-6, organic contains >30% of organic matter by weight (or >50% by volume) Soil components: soil matrix, mineral(inorganic) materials, organic matter. Volume composition of a loam surface soil: 40% sand, 40% silt, 20% clay. Mineral constituents in soil: sand, silt and clay particles have diameter smaller than 2 mm, relative proportions of these 3 in a soil is soil texture.
