Which components are included in soil organic matter?

Soil organic matter is a crucial component of soil health, playing a significant role in nutrient cycling, soil structure, and microbial activity. The correct response highlights that soil organic matter is made up of organic residues (such as decomposed plant and animal materials), protected organic matter (which is more resistant to decomposition and can persist in the soil), biomass (the living microorganisms and organisms within the soil), and by-products of microbial activity (which contribute to the organic matter pool).

These components work together not only to enhance soil fertility by improving nutrient availability for plants but also to improve soil structure and water retention. This richness in organic matter supports a diverse ecosystem within the soil, contributing to overall soil health and productivity.

In contrast, components such as sand, silt, and clay represent the mineral part of the soil and do not contribute to organic matter. Rocks and minerals also refer to the inorganic aspects of soil and similarly do not pertain to organic matter. Matric potential and bulk density are physical properties of soil that do not directly reflect the organic content; rather, they are related to soil water retention and compaction, respectively.