soil science Soil science is the study of soil as a natural resource on the surface of the Earth including soil formation, soil classification, classification and Soil survey, mapping; Soil physics, physical, Soil chemistry, chemical, Soil biology, biologica ...

, peds are aggregates of soil

particles In the physical sciences, a particle (or corpuscle in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from s ...

formed naturally as a result of pedogenic processes; this natural organization of particles forms discrete units separated by pores or voids. The term is generally used for

macroscopic The macroscopic scale is the length scale on which objects or phenomena are large enough to be visible with the naked eye, without magnifying optical instruments. It is the opposite of microscopic. Overview When applied to physical phenome ...

(visible; i.e. greater than 1 mm in size) structural units when observing soils in the field. Soil peds should be described when the soil is dry or slightly moist, as they can be difficult to distinguish when wet. An artificially formed aggregate of soil particles can be called a clod.{{cite book , title=A dictionary of earth sciences , edition=2nd , publisher=

Oxford University Press Oxford University Press (OUP) is the publishing house of the University of Oxford. It is the largest university press in the world. Its first book was printed in Oxford in 1478, with the Press officially granted the legal right to print books ...

, last1=Allaby , first1=Ailsa , last2=Allaby , first2=Michael , year=1999 , location=Oxford, United Kingdom , isbn=0-19-280079-5 , url-access=registration , url=https://archive.org/details/dictionaryofeart00alla , access-date=10 June 2025 There are five major classes of

macrostructure Macrostructure may refer to: * Macrostrucure (engineering) * Macrostructure (linguistics) * Macrostructure (psychology) * Macrostructure (sociology) See also *Microstructure Microstructure is the very small scale structure of a material, def ...

seen in soils: platy, prismatic, columnar,

granular Granularity (also called graininess) is the degree to which a material or system is composed of distinction (philosophy), distinguishable pieces, granular material, "granules" or grain, "grains" (metaphorically). It can either refer to the exten ...

, and blocky. There are also structureless conditions. Some soils have simple structure, each unit being an entity without component smaller units. Others have compound structure, in which large units are composed of smaller units separated by persistent planes of weakness.

References

Soil