Pedon
The pedon is the smallest spatial unit in soil science .
The term was introduced in its current meaning in North America in 1960. According to the mapping instructions of the United States Department of Agriculture , the pedon corresponds to the basic mapping unit. The expansion of a pedon is handled differently. Often it is conventionally assigned a size of one to ten square meters. The minimum size results from the fact that all soil horizons in their variability and spatial extent must be represented in it. The term pedon is used in DIN 4047-3 with the same meaning.
Neighboring peda of the same soil shape are conceptually combined into a unit, the polypedon . A polypedon is the smallest unit of uniform soil shape. If interpreted strictly, the spatial extension of a polypedon would be a pedotope ; but the terms polypedon and pedotope are often used synonymously . If neighboring Polypeda are so intertwined that it would be impossible to break them down even with detailed mapping, they are grouped into pedocomplexes from a pedological point of view. This is regularly necessary for vertisoles , for example .
The delimitation of a pedon, like the delimitation of a polypedon, is more or less arbitrary, in order to be able to examine it adequately according to the definition, it would have to be de facto destroyed by this examination. The American soil scientist George Holmgren proposed a modification of the Pedum concept. He argues that the pedon and polypedon are in fact abstract; H. Units that cannot actually be mapped in the terrain that were only proposed to assign the information from a soil profile record, a profile pit or borehole to an arbitrary three-dimensional unit, the existence of which is more metaphysically required than empirically justified. According to him, a pedon should be understood as punctiform, i.e. without spatial correspondence. Although many editors agree with Holmgren in principle and in particular declare the derived term polypedon to be unmanageable, the term has so far been used in practice.
By definition, a pedon extends as far as pedogenically unchanged rock, but according to the American definition only if it is found at a depth of up to two meters. A shallower section of the ground that only includes the pedogenically modified depth range is called a solum .
Individual evidence
- ^ RW Simonson & DR Gardiner (1960): Concept and functions of the pedon. Transactions of the 7th international Congress of Soil Science vol 4: 127-131.
- ^ JG Bockheim, AN Gennadiyev, RD Hammer, JP Tandarich (2005): Historical development of key concepts in pedology. Geoderma 124: 23-36. doi: 10.1016 / j.geoderma.2004.03.004
- ^ Soil Survey Division Staff, 1993: Soil survey manual. Soil Conservation Service. US Department of Agriculture Handbook 18. online Definition Pedon: Introduction, p.15
- ↑ DIN German Institute for Standardization: DIN 4047-3: Agricultural hydraulic engineering, terms, part 3: Soil science, soil systematics and soil research. Beuth-Verlag, Berlin, 2002.
- ↑ P. Schachtschabel, H.-P. Blume, C. Brümmer, K.-H. Hartge, U.Schwertmann: Scheffer / Schachtschabel textbook of soil science. 12th edition, 1989. Enke Verlag, Stuttgart. ISBN 3-432-84772-6 . on p. 450.
- ↑ LP Wilding, IV Kovda, EC Morgun, D. Williams (2002): Reappraisal of the Pedon Concept for Vertisols: Consosiations or Complexes? Transaction of 17-th International Congress of Soil Science, paper 872 (12 pp.)
- ^ Francis Doan Hole & James B. Campbell: Soil Landscape Analysis. Rowman & Littlefield Publishers, 1985. ISBN 978-0-86598-140-9 . Pp. 116 and 117
- ↑ George GS Holmgren (1988): The Point Representation of Soil. Soil Science Society of America Journal 52: 712-716. doi: 10.2136 / sssaj1988.03615995005200030022x