The main source of organic material in soil is?

The main source of organic material in soil is decomposed plant and animal matter, primarily in the form of leaf litter, dead roots, and other organic residues. Microorganisms and soil fauna, such as earthworms, play a crucial role in breaking down this organic matter, leading to the formation of humus. This organic matter enhances soil fertility, structure, and moisture retention, supporting plant growth and ecosystem health.