Soil Science Flashcards

Grade 6 · Science · Flashcards

Review key vocabulary about soil formation, composition, layers, and importance.

Flashcards

Soil: A complex mixture of weathered rock particles, organic matter, water, air, and living organisms.
Weathering: The physical and chemical breakdown of rock into smaller particles; the starting point of soil formation.
Physical weathering: Rock breaking by mechanical processes like freeze-thaw cycles, root growth, or wind abrasion.
Chemical weathering: Rock breaking through chemical reactions, such as rainwater (weak acid) dissolving minerals.
Humus: Dark, nutrient-rich organic matter formed by decomposition of plants and animals; key to soil fertility.
Soil horizon: A distinct layer in soil; each horizon has different characteristics.
O horizon: Surface layer of partially decomposed organic material (leaf litter).
A horizon (topsoil): Most fertile layer; dark with humus; where most plant roots grow.
B horizon (subsoil): Below topsoil; less organic matter; accumulates minerals leached from above.
C horizon: Partially weathered parent rock; transitional layer above bedrock.
Erosion: The removal and transport of soil by wind, water, or ice.
Sandy soil: Large particles; drains quickly; poor at holding water and nutrients.
Clay soil: Tiny particles; retains water well but can become waterlogged and compacted.
Loam: Ideal garden/crop soil with balanced proportions of sand, silt, and clay.
Decomposition: The breakdown of dead organic matter by bacteria, fungi, and other decomposers into humus and nutrients.