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Soils in this order are composed primarily of organic mater and include soils commonly known as peat, bog or fen soils. Most of these soils are saturated with water for prolonged periods of time. Organic soils contain 17% organic C (or 30% organic matter) by weight. Soils of the Organic order are the dominant wetland soils found in forested regions of Canada but they also occur in non-wetland positions in upland sites where leaf litter accumulates.

The master horizon for the wetland Organic soils is the O horizon. The three decomposition stages are assigned Of, Om, or Oh designations depending on the degree of decomposition of the organic material. The upland versions of the Organic order are composed of leaf litter and other woody debris, which are termed folic materials. These organic horizons are assigned an L, F, or H designation, depending again on the degree of decomposition.

The placement of wetland organic soils into the three main great groups of the Organic order depends on depth relationships of the organic layers within the control section. For Organic soils the control section extends from the surface to a depth of 1.6 m (or to a contact with mineral soil or bedrock if this occurs within 1.6 m of the surface). Organic soils are divided into four great groups. Three of these represent Organic soils formed in wetlands and are separated on the basis of degree of decomposition of the organic material. The fourth represents organic soils formed in upland organic materials and are soils that are only briefly saturated with water.