Soil structure is the shape a soil takes according to its physical as well as its chemical properties. Soil is constructed of secondary components called aggregates or peds. Soil aggregates are determined by their shape, size and distinctness. Abiotic processes such as wetting and drying or freezing and thawing develop soil structure, while biotic processes such as compression by roots, burrowing by earthworms, and fungal hyphae develop the soil structure over time, according to scientists at the University of British Columbia.
Granular soil appears as small pieces of rock or dirt, like pieces of cookie crumbs according to the Soil Science Education website, run by NASA. The crumbs of soil are less than 0.2 inch in diameter and are often found on the surface horizon, or surface layer, of soil. Granular is susceptible to quick change due to weather conditions and human activity.
Block soil type is made up of rocks between 0.6 inch and 2 inches in diameter. Blocky conditions are often found in the A or B horizons of the soil layers and are more often found in regions that are, or once were, humid, according to the University of British Columbia.
Prismatic soil is made up of vertical columns of soil. It is usually found in the lower horizons and is found in arid regions.
Columnar soil structures have the same appearance as prismatic soil, appearing in vertical columns, but they have a cap of salt at the end.
Platy soils are thin, looking like stacked plates when viewed from the side. This type of soil structure is usually found in compacted soil regions.
Single grained is soil that is broken into small particles that do not stick together and has a loose consistency. It is easily poured from the hand. This is commonly found in sandy soils, in the top horizons.
Massive is a soil type that has no visible particles and no visible structure. It is difficult to break down into smaller pieces and is usually found as large, unworkable clods.