Which of the following contributes to soil organic matter?

Soil organic matter is vital for maintaining soil health and fertility, as it enhances the soil's physical and chemical properties while supporting biodiversity. The correct answer emphasizes that various components contribute to soil organic matter, not just a single source.

Protected organic matter refers to organic material that is stabilized within the soil, often becoming resistant to decomposition. This includes substances such as humus, which significantly improves soil structure and water retention. Biomass constitutes living organisms in the soil, including plant roots and microbial communities, which contribute to the organic content through growth and decay processes.

Additionally, residues from crops and other plants provide a continuous input of organic material as they decompose. By-products, which can come from agricultural practices and other organic waste, also add to the overall organic matter in the soil.

The inclusion of these multiple sources illustrates that soil organic matter is a product of various biological and chemical processes, resulting from both living and decomposing materials. This holistic view of organic matter contributes to a productive and healthy soil ecosystem.