Which organism primarily recycles nutrients and decomposes organic matter in soil?

• A. Fungi
• B. Earthworms
• C. Bacteria
• D. Collembola

Answer: (D)

Decomposition and nutrient recycling in soil are driven primarily by microbial decomposers. Bacteria and fungi break down complex organic matter into simpler compounds that plants can take up, mineralizing nutrients like nitrogen and phosphorus in the process. Fungi are especially adept at breaking down tough plant polymers such as cellulose and lignin, making them critical players in turning litter into usable nutrients. Bacteria also play a vital role by rapidly mineralizing more readily available substrates, contributing to quick nutrient turnover. Earthworms improve the rate of decomposition indirectly by mixing soil, exposing more surface area for microbes, and aiding aeration, but they don’t perform the chemical breakdown themselves on the same scale. Collembola (springtails) help by shredding litter and grazing on fungi, which can speed nutrient release, yet their role is supportive rather than the main driver of decomposition. In short, the main nutrient recycling and organic matter decomposition are carried out by microbial decomposers, with fungi (and bacteria) as the primary agents.