Download Soil Science: Understanding Soil Profiles and Horizons and more Quizzes Environmental Science in PDF only on Docsity! TERM 1 Soil profile DEFINITION 1 A soil horizon is a layer parallel to the soil surface, whose physical characteristics differ from the layers above and beneath. adescription of thedifferent, naturallyformed layerswithin a soil TERM 2 Horizons DEFINITION 2 horizontal layers ofsoil from soil formation TERM 3 A Horizon DEFINITION 3 Top soil (mixed humus and leached mineral soil)topmost layer of soil Dead organic matter (detritus) deposited by plants High in organic content Primary source of energy for the soil community TERM 4 O Horizon DEFINITION 4 Humus (surface litter, decomposing plant matter)topmost layer of soil Dead organic matter (detritus) deposited by plants High in organic content Primary source of energy for the soil community TERM 5 E Horizon DEFINITION 5 Zone of leaching (less humus, minerals resistant to leaching)pale-colored layer below the A horizon Eluviation: process of leaching (dissolving) minerals due to downward movement of water TERM 6 B Horizon DEFINITION 6 Subsoil (accumulation of leached minerals like iron and aluminum oxides)below the E horizon Contains minerals leached from the A and E horizons High in iron, aluminum, calcium, other minerals, clay Reddish or yellow colored from oxidized metals TERM 7 C Horizon DEFINITION 7 Weathered parent material (partly broken-down minerals)parent mineral material Weathered rock, glacial deposits, volcanic ash Reveals geologic process that created the landscape Not affected by biological or chemical processes TERM 8 Detritus DEFINITION 8 Leaves, stems, flowers, seeds derived from plantscontinual decomposition TERM 9 Detritus Food Web DEFINITION 9 Biological breakdown of detritus to humusbioturbation and mixing with mineral particlesnitrogen fixation TERM 10 Mineral Particles DEFINITION 10 Parent materials, leached minerals, weathered clay, sand, silt from bedrock, glacial deposits, wind and alluvial deposits are all TERM 21 Oxisols DEFINITION 21 soils of tropical and subtropical rain forestsThe B horizon has a layer of iron and aluminum oxides Little O horizon: rapid decomposition of vegetationLimited agriculture: minerals are in living plant matter TERM 22 Alfisols DEFINITION 22 widespread, moderately weathered soils found in moist, temperate forests Well-developed O, A, E, and B horizons Suitable for agriculture if they are fertilized TERM 23 Aridisols DEFINITION 23 soils of drylands (arid, semiarid, andseasonally dry areas) and deserts Unstructured (lack of vegetation and precipitation) Thin, light colored TERM 24 Hydric DEFINITION 24 important, but not for agricultureThese soils indicate a wetland or aquatic site Not a soil class, but belong to other classes Used to delineate wetland boundaries for development or protection TERM 25 Histosols DEFINITION 25 an order that contains several types of hydric soils They contain peat (undecayed vegetion) TERM 26 Peat DEFINITION 26 undecayed vegetation TERM 27 Gelisols DEFINITION 27 a soil order of permanently frozen soil (permafrost) TERM 28 Soil fertility DEFINITION 28 the soils ability to support plantgrowthThe presence of nutrients and all other needs TERM 29 Tilth DEFINITION 29 A soils ability to support plant growth TERM 30 Fertilizer DEFINITION 30 nutrients added to replace those that are lost TERM 31 Leaching DEFINITION 31 nutrients are washed from the soil by waterDecreases soil fertility and contributes to water pollution TERM 32 Nutrient-holding capacity DEFINITION 32 the soils capacity to bind and hold nutrient ions until they are absorbed by roots TERM 33 Infiltration DEFINITION 33 water soaks into the soil Water runoff is useless to plants and may cause erosion TERM 34 Water-holding capacity DEFINITION 34 soils ability to hold water after it infiltrates TERM 35 Poor holding capacity DEFINITION 35 water percolates below root level
