(from Greek histos, "tissue") are soils that are composed mainly of organic materials. They contain
at least 20-30% organic matter by weight and are more than 40 cm
thick. Bulk densities are quite low, often less than 0.3 g cm3.
Most Histosols form in settings such as wetlands where restricted
drainage inhibits the decomposition of plant and animal remains,
allowing these organic materials to accumulate over time. As a result,
Histosols are ecologically important because of the large quantities
of carbon they contain. These soils occupy ~1.2% of the ice-free
land area globally and ~1.6% of the US.
Histosols are often referred to as peats and mucks and have physical
properties that restrict their use for engineering purposes. These
include low weight-bearing capacity and subsidence when drained.
They are mined for fuel and horticultural products.
Histosols are divided into
5 suborders: Folists, Wassists, Fibrists, Saprists,
and Hemists. Click
here for more information about these suborders. Click
here to view a map of their distribution in the US.