What condition must be met for a spodic horizon to be identified below an albic layer?

The identification of a spodic horizon below an albic layer requires specific characteristics, particularly related to organic matter accumulation and mineral interactions. For a spodic horizon to be classified, it must exhibit a concentration of organic compounds and iron, as well as specific soil pH levels that indicate the presence of illuvial materials, which are leached from the overlying albic layer.

This zone is typically acidic and enriched with organic carbon that has undergone transformation in the soil environment due to microbial activity. The presence of these conditions ensures that the spodic horizon meets the definition based on its mineral and chemical characteristics.

Other options may describe soil properties that can exist in various contexts but do not specifically define the conditions necessary for a spodic horizon formation. For instance, while high clay content may influence soil characteristics, it does not directly relate to the spodic horizon criteria, just as the presence of a gleyed matrix or low nutrient availability does not specifically denote the unique properties required to classify a spodic horizon beneath an albic layer.