histosol

Histosol is a soil order in the USDA Soil Taxonomy characterized by the dominance of organic material in the upper part of the soil profile. These soils form in water-saturated environments where plant matter accumulates faster than it decomposes, typically in wetlands such as bogs, fens, swamps, and other depressions that remain saturated for long periods.

Histosols are commonly known as organic soils and are distinguished by their high organic matter content and low mineral matter. They are often described as peat or muck: peat is partially decomposed plant material, while muck is more completely decomposed and darker in color. The horizons are frequently thick and lack well-developed mineral layers; bulk density is generally low and cation exchange capacity is elevated due to the organic matter. pH can range from acidic to neutral, depending on drainage, vegetation, and mineral inputs.

Geographically, histosols occur worldwide, particularly in cool to temperate and some tropical wetland regions. They support unique ecosystems and provide functions such as water storage, habitat provision, and carbon sequestration. They have historical and economic importance for horticulture and energy (peat extraction); however, drainage or disturbance can lead to subsidence, oxidation of the organic matter, and release of stored carbon. Restoration and management often focus on rewetting to maintain hydrology and preserve ecosystem services.

In management contexts, histosols require careful handling because their organic matter content makes them vulnerable to compaction, subsidence, and carbon release when aerated. They are typically left undisturbed in natural settings and are subjected to drainage with caution when agricultural or industrial use is considered.