Soil Science_03_Soil ABC 2024 PDF

KORTU162N – Soil Science E-Learning portal: KORTU162N - Soil Science - 2024/2025 - autumn This „Soil science” learning material is the intellectual property of the colleagues of the Institute of Environmental Sciences of the Hungarian University of Agriculture and Life Sciences. It can onl...

KORTU162N – Soil Science E-Learning portal: KORTU162N - Soil Science - 2024/2025 - autumn This „Soil science” learning material is the intellectual property of the colleagues of the Institute of Environmental Sciences of the Hungarian University of Agriculture and Life Sciences. It can only be used by other institutions with our permission! Contact: [email protected] The soil body concept A three-dimensional body of soil with lateral dimensions large enough to represent and study of the characteristic horizons (1 to 10 m2) 1 m2 10 m2 Pedon Pedon  MASTER HORIZONS AND LAYERS The capital letters like H, O, A, E, B, C and R represent the master horizons and layers of soils. The capital letters are the base symbols to which other characters are added to complete the designation (i.e. 2Btg1). Most are genetic soil horizons, reflecting a qualitative judgement about the kind of changes which have taken place. Genetic horizons are not equivalent to diagnostic horizons, although they may be identical in soil profiles. Diagnostic horizons are quantitatively defined features used in classification.  MASTER HORIZONS AND LAYERS Code Determination Mineral horizons A Surface or near-surface mineral horizon with some organic accumulation, usually a darker colour than underlying horizons and/or smaller clay content than underlying horizons. E A near-surface mineral horizon characterized by a loss of clay, iron, aluminium, or some combination of these; usually lighter in color (higher value and/or lower chroma) than the overlying A and underlying B. B A mineral horizon characterised by one or more of the following: a concentration of clay, iron, aluminium, organic material or several of these; a structure and/or consistence unlike the horizons above and below; stronger colours (higher chroma and/or redder hue) than the horizons above and below. C Consolidated or unconsolidated material, usually partly weathered, little affected by pedogenic processes. R Hard bedrock that cannot be cut with a spade. Organic horizons O Horizons dominated by organic material consisting of undecomposed organic materials that have accumulated on the surface of either mineral or organic soils. O horizons are not saturated with water for prolonged periods. H These horizons dominated by organic material formed from accumulations of undecomposed or partially decomposed organic material. All H horizons are saturated with water for prolonged periods, or were once saturated but are now drained artificially.  H horizon H horizons are dominated by organic material formed from accumulations of undecomposed or partially decomposed organic material at the soil surface, which may be underwater. All H horizons are saturated with water for prolonged periods, or were once saturated but are now drained artificially.  O horizon O horizons are dominated by organic material consisting of undecomposed or partially decomposed litter, such as leaves, needles, twigs, moss and lichens, that has accumulated on the surface of either mineral or organic soils; O horizons are not saturated with water for prolonged periods.  A horizon Surface or near-surface mineral horizon with some organic matter (humus) accumulation, usually with darker colour and/or smaller clay content than underlying horizons.  E horizon A near-surface mineral horizon characterized by a loss of clay, iron, aluminum, or some combination of these; usually lighter in color (higher value and/or lower chroma) than the overlying A and underlying B.  B horizon Mineral horizon that formed below an A, E, O or H horizon, characterised by one or more of the following: illuvial concentration of silicate clay, iron, aluminium, humus, carbonates, gypsum or silica (alone or in combination) ; accumulation of sesquioxides; evidence of removal of carbonates; a structure and/or consistence unlike the horizons above and below; stronger colours (higher chroma and/or redder hue) than the horizons above and below. B horizon illuvial accumulation transitional B horizon B horizon  C horizon or layer Horizons or layers, excluding hard bedrock, that are little affected by pedogenetic processes, and lack properties of H, O, A, E or B horizons.  R layer Hard bedrock underlying the soil. Air-dry chunks of an R layer when placed in water willLösz not slake within 24 hours.  Transitional horizons Vertical subdivisions Discontinuities A A A AB A/C C C B Bt1 2CR Bt2 3B A Transitional horizons A AB those with properties those with A/C of two horizons the two properties superimposed separate C B BC For horizons dominated When distinct parts have by properties of one recognizable properties master horizon but of two kinds of master C having subordinate horizons properties of another i.e. E/B, B/E, B/C or C/R i.e. AB, EB, BE or BC The dominant horizon’ symbol is the first Transitional horizons * A A AB A/C B C BC C * Without subordinate distinctions!  Vertical subdivisions A horizon/layer may be further subdivided on the basis of evident morphological features (i.e. structure, colour or texture) using Arabic numerals, which follow all the letters. These subdivisions are Clay numbered consecutively. accumulation (Bt) horizon The numbering starts with 1 at whatever level in the profile, i.e. Bt1-Bt2-Btk1-Btk2 Vertical subdivisions A horizon/layer may be further subdivided on the basis of evident morphological features (i.e. structure, colour or texture) using Arabic numerals, which follow all the letters. Bt1 These subdivisions are numbered consecutively. The numbering starts with 1 at Bt2 whatever level in the profile, i.e. Bt1-Bt2-Btk1-Btk2  Discontinuities A A In mineral soils, Arabic numerals are used as prefixes to indicate discontinuities. B Numbering starts with the second layer of B contrasting material, which is designated „2”. Underlying contrasting layers are 2C numbered consecutively. 2C Where two or more consecutive horizons formed in one kind of material, the same prefix number applies to all of the horizon 3C designations in that material. 3Bt In organic soils, discontinuities between different kinds of layers are not identified. 4C 3C  Subordinate distinctions within master horizons Suffix Short description Used for b Buried genetic horizon mineral horizons c Concretions or nodules mineral horizons d Dense layer (physically root restrictive) mineral horizons g* Stagnic conditions / *USA strong gley no restriction h Illuvial accumulation of organic matter mineral horizons i/*ss Slickensides / *USA mineral horizons k Accumulation of pedogenetic carbonates no restriction l* Capillary fringe mottling (gleying) *only in FAO no restriction n Pedogenetic accumulation of exchangeable sodium no restriction no restriction p Ploughing or other human disturbance E, B or C as Ap r* Strong reduction *only in FAO no restriction s Illuvial accumulation of sesquioxides B horizons t Illuvial accumulation of silicate clay mineral horizons w Development of colour or structure B horizons z Pedogenic accumulation of salts more soluble than gypsum no restriction Suffix Short description Used for b Buried genetic horizon mineral horizons Ap Ap AB C B 2Ab Ab 2Blb C 2Cl Suffix Short description Used for c Concretions or nodules mineral horizons Bc Bc Suffix Short description Used for d Dense layer (physically root restrictive) mineral horizons Ad Suffix Short description Used for g* Stagnic conditions / *USA strong gley no restriction Bg Suffix Short description Used for h Illuvial accumulation of organic matter mineral horizons O A E Bhs C Suffix Short description Used for i/*ss Slickensides / *USA mineral horizons Bi / Bss Suffix Short description Used for k Accumulation of pedogenetic carbonates no restriction Bk Suffix Short description Used for Capillary fringe mottling (gleying) no restriction l* *only in FAO Cl Suffix Short description Used for Pedogenetic accumulation of no restriction n exchangeable sodium Btn Suffix Short description Used for no restriction p Ploughing or other human disturbance E, B or C as Ap Ap Ap Suffix Short description Used for s Illuvial accumulation of sesquioxides B horizons Bhs Suffix Short description Used for t Illuvial accumulation of silicate clay mineral horizons Bt Suffix Short description Used for r* Strong reduction *only in FAO no restriction Cr Cr Suffix Short description Used for w Development of colour or structure B horizons Bw Suffix Short description Used for Pedogenic accumulation of salts more no restriction z soluble than gypsum Az Apk Apk/Ck Ck 2Ck O A E Bt Ck1 Ck2