Initial Humus Form with surface layers in a developing stage can be observed on parent material poor in bases, and with vegetation providing litter of low decomposability, such as conifer trees, dwarf shrubs or wavy hair grass (Deschampsia flexuosa). If an Of horizon occurs, it is partly differentiated in Olf and Ohf. An A horizon from recent soil development is often absent, frequently an Ai horizon occurs. Distinct features are:
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Ol horizon is present;
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Of horizon is frequently present, but of minor thickness and incomplete; and
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Oh horizon is absent.
Organic surface layer of an Initial humus form with surface layers on dune sands (Photo: Gerhard Milbert).
