Soils unit 1

what is soil

definition can vary depending on your field, a naturally occurring body extending from water to rock that is or is capable of supporting life

dirt

misplaced soil, a loose term that can be contested, generally soil moved to where its not supposed to be, if the intended use is to grow plants its usually still called soil

pedological approach

study of soil as it occurs in nature (origin, classification, description)

edaphological

study of soil as it relates to plant growth, (availability, nutrients, fertility, acidic/alkaline)

soil profile

vertical section of soil made up of horizons

a horizon

surface soil

E horizon

not in all soils, zone of leaching (clay and o.m.)

B horizon

zone of accumulation, subsoil, collects material leached from E horizon

C horizon

parent material, where the rest of the soil formed from

o horizon

organic horizon, not in all soils only in organic soils, found above A horizon, rarer

r horizon

bedrock below all other horizons

importance of soil horizon knowledge

how deep plant roots go and what is available for them at that depth, water sinking through various layers

regolith

the unconsolidated mantle of weathered rock and soil material on the earths surface, everything above bedrock

soil solum

soil material above plant material

parent material

unconsolidated and chemically weathered material or organic matter from which the soil may have developed

master horizons

only O, A, E, B, C, R,

the colloquial soil

the upper few feet of regolith that differs from the deeper parent material due to the weathering action of; wind, water, heat, and biological activity

surface soil characteristics (a horizon)

most O.M. matter found here, supports worms bacteria and fungi, major root development zone, source of mineral nutrients and H2O, subject to manipulation and management

Ap horizon

the plowing layer, amount of soil 6 2/3 inch deep in an acre, = 2 mil pounds of soil

subsoil characteristics (b horizon)

always has an upper (transition) zone, graduation of A horizon dominated by silicate clay and Fe/Al oxides due to accumulation, subject to little alteration, may influence surface soil (water infiltration or lack thereof)

Ab horizon

when the transition between A and B gets so big it’s its own thing

mineral soil

composition characterized by inorganic materials, has to be less than 20% organic material, Illinois has around 1-5%, can be changed through manipulation

organic soil

characterized by organic content = to or greater than 20%, peat and muck soils can have as high as 90% OM, has O horizon which usually goes strait to c horizon, organic matter accumulation means the parent material never develops soil

components of soil

solids (inorganic or organic), pore space (air or water)

ideal soil

50% pore space (20-30% of water/air) 50% solids (45% mineral 5% organic)

primary mineral constituents

often quartz, feldspars, and mica, persist over time with little change in chemical composition, easiest to find in c horizon, quartz is 2% of earths crust

secondary mineral constituents

material that has weathered from primary minerals, clay/fine particles, clay is a philosilicate

mineral weathering process

feldspars/mica → clay → illiate (arid west) → montomorilliate (IL+IN) → koalinite (SE america) → Fe+Al hydrous oxides

organic constituents (organic soil perspective)

Oi horizon/organic litter- non decomposed leaf litter

Oe horizon- partially decomposed litter

Oa- humified material, not recognizable

organic constituents (mineral soil)

organic matter or humus (end product), resistant end product of o.m. decomp. usually dark in color, the more black the more humidified