What process do soil microbes perform to release nutrients from organic matter?

• A. Immobilization
• B. Adsorption
• C. Titration
• D. Mineralization

Answer: (D)

Nutrients are released from organic matter by mineralization, a microbial process. As soil microbes such as bacteria and fungi break down organic matter (dead plants and animals, and their wastes), they enzymatically decompose complex organic compounds and convert the nutrients bound in those compounds into inorganic forms that plants can uptake, like ammonium and nitrate for nitrogen, phosphate, and sulfate. This transformation makes nutrients available for plant uptake and is a key part of the nitrogen and overall nutrient cycles in soils.

Immobilization is the opposite: microbes take up inorganic nutrients to build their own biomass, temporarily reducing what’s available to plants. Adsorption involves nutrients sticking to soil particles, which can delay movement or release but does not by itself release nutrients from organic matter. Titration is simply a chemical measurement method, not a biological release process.