Which great group includes all Mollisol types?

Mollisols are characterized by a thick, dark, organic-rich surface horizon known as mollic epipedon, which is typically found in grassland ecosystems. The great group that encompasses all Mollisol types is Haplodolls. This is because Haplodolls represent the typical profile of Mollisols, which displays the essential features that define the group, including high fertility and a strong presence of calcium carbonate at depth.

Understanding the structure and characteristics of mollisols is crucial, as they provide significant agricultural value due to their moisture-holding capacity, nutrient content, and soil structure. This group is important in terms of land use and agricultural practices, particularly in regions that are conducive to maintaining grassland soils.

The other options listed do not represent all Mollisol types. For instance, Aridisols are desert soils characterized by low moisture, and Entisols are recent soils without significant horizon development. The Argi great group also pertains to a different type of soil, typically associated with clay-rich horizons, which does not apply to all Mollisols. Thus, the recognition of the Haplodolls great group as encompassing all Mollisol types is rooted in their defining characteristics and their critical role in soil science.