Histosols 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. Histosols typically form in settings where poor drainage inhibits the decomposition of plant and animal remains, allowing these organic materials to accumulate over time. Histosols are often referred to as peats and mucks. Histosols are soils that form in decaying organic matter.  In low, wet places, like the bogs shown or the marshes below, organic matter accumulates below the water table and decomposes more slowly than it accumulates. 
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Over time, thick accumulations of this material can form.  The pond excavation below shows such an accumulation of muck.  The gray material at the base of the pit is the sand that underlies it.

Peat is the name given to slightly decomposed organic material in soil, while muck is used for the rotten, highly decomposed material.  Muck is often black in color, and slimy to the touch.  Note the soil profile below, in which about 50 cm of muck overlies gray sand.  Note also the shallow water table.

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Histosols are scattered throughout both the Upper and the Lower Peninsula. They are found in marshy areas with a thick vegetation that does not decompose completely, and much of the soil consists of undecayed vegetable matter or peat. These soils are chiefly found in lacustrine areas that were covered with water or were drainage channels during the glacial period. In some places, depressions were filled with shallow lakes, and these have overgrown with vegetation and gradually changed from lake to swamp to organic soil.

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Histosols occur on young landscapes where there are lots of wetlands.  Young, recently-deglaciated landscapes like those in Michigan therefore contain lots of wetlands, and in these Histosols form.  Nearly 1/7 of Michigan's land surface is underlain by Histosols, as the map above shows.
    Saprists are Histosols that are mostly muck, and dominate the Michigan landscape.  Hemists contain material that is more like peat (i.e., less decomposed).   Notice that the Hemists are located in the cooler parts of the Great Lakes region, where decomposition of the organic materials is slowed.

Histosols have many uses, although most remain today in undrained wetlands.  Here they serve as important habitat for wetland plants and animals, and serve as carbon reservoirs.  Nonetheless, humans have found ways to drain such wetlands and use the Histosols. 
    The peat that has accumulated in the drift depressions and glacial lake beds is used for fuel, potting soil, litter, in greenhouses and for packing. 
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One important use is as a growing medium (often, potting soil).   The Histosol landscapes are first drained, and the muck mined, much as you would mine gravel from a gravel pit.  The muck is then piled up in huge piles to "dry" (see below).
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Eventually, the muck is bagged and sold as "soil".
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Another major use of Histosols is as a growing medium in place (i.e., the soil is not removed, instead, plants are grown on the mucks).  In order to grow crops on mucks, the land must first be drained.  Usually this involves digging deep drainage ditches, installing underground drainage tile (perforated pipes) into the muck, and then pumping the water from the drain tile into the ditches (see below).  Once in the ditches, the water can drain away and the muck landscape is dry.
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As is shown in the image above and the one below, growing sod, or turf, is a popular land use on mucks. 

Histosols are fertile, and therefore grow turf very readily.   Because the muck is organic and not mineral, "peeling" the turf off and rolling it up into rolls for shipment is easy. 
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Of course, every time a layer of sod is removed from the field (about once every two years), some of the muck is lost, and the soil "resource" is diminished.   Eventually, the field gets lower and lower, and wetter and wetter, as is shown below.
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Ultimately, the field must be abandoned, either because the muck has been mined away and only the underlying clay or sand remains, or because it is too low and wet.

This type of soil is very poorly drained and can be cultivated only if artificially drained. When a sandy peat is drained, the soil often becomes very light and is subject to erosion by the wind, so rows of willow trees or bushes are often planted in strategic places on the borders of these fields to act as windbreaks. Often, such soil must be irrigated to offset the rapid loss of moisture during the summer.

Finally, organic soils are heavy producers of vegetables and other specialized crops (such as mint) in Michigan.  Many of our vegetables are grown on drained Histosols.  Note the head lettuce being grown on deep muck (below).  Histosols are particularly adapted to vegetables not only because of their inherent fertility, but because the soil is very loose and roots can develop in them quite easily.  Note also (below) that these mucks must usually be irrigated, since they do not hold much water, and the water table has been lowered by artificial drainage.
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Go here to learn more about crops grown on mucks.

Parts of the text on this page have been modified from L.M. Sommers' book entitled, "Michigan: A Geography".

This material has been compiled for educational use only, and may not be reproduced without permission.  One copy may be printed for personal use.  Please contact Randall Schaetzl (soils@msu.edu) for more information or permissions.