Nonhumus is a term used in pedology, which refers to the uppermost layer of mineral soil found beneath the organic-rich humus layer. It is a zone containing mineral particles that have not undergone decomposition and therefore do not possess organic matter. Nonhumus is typically comprised of minerals such as sand, silt, and clay.
This layer plays a crucial role in soil formation and composition, as it directly underlies the layer of humus and helps to provide a balanced structure for the soil. Nonhumus assists in retaining water and allowing for drainage, as its composition determines the soil's textural properties. The mineral particles within this layer can influence the soil's capacity to hold moisture and nutrients, as well as its fertility and porosity.
Oftentimes, nonhumus is categorized into specific horizons or layers within the soil profile, such as the E horizon or the B horizon. These horizons differ in terms of their mineral composition, depth, and other soil properties. The nonhumus layer may vary in thickness depending on factors such as climate, vegetation, and parent material. In areas where organic matter accumulates rapidly, the nonhumus layer may be relatively thin. Conversely, in regions with low organic matter input, the nonhumus layer may be deeper.
Overall, nonhumus constitutes an integral part of the soil, influencing its physical and chemical properties. By providing a foundation for organic matter, it directly impacts soil fertility, water-holding capacity, and nutrient availability.
