Initial humus forms developing to a mull-like humus form are described as Initial Mull. The mineral topsoil is characterised by a medium to high content of bases, partly contains lime. The decomposability of litter is medium to high. Features of an Initial Mull are:

• Ol horizon is present;
• if an Of horizon is present, it is of minor thickness or is incomplete;
• a horizon is of minor thickness and less structured or an A horizon is absent; and
• distinct features of earthworm activity, e.g., earthworm channels, middens and casts are rarely observed.