What is soil respiration and its significance in carbon cycling?

• A. Release of CO2 from soil due to root respiration and microbial activity; important for carbon balance and nutrient cycling.
• B. Absorption of CO2 from atmosphere by soil microorganisms.
• C. Release of methane from soils exclusively.
• D. Soil respiration has no role in carbon cycle.

Answer: (A)

Soil respiration is the release of carbon dioxide from the soil as both roots respire and soil microbes decompose organic matter. This process returns carbon from soil organic matter back to the atmosphere and reflects how actively the soil ecosystem is mineralizing nutrients for plants. Because it links carbon flow with nutrient cycling, it helps determine soil carbon stocks and overall ecosystem productivity. The rate depends on temperature, soil moisture, the availability of organic substrates, and root activity, so it changes with climate and land management. It is not a process of absorbing CO2, it is not about methane, and it definitely plays a major role in the carbon cycle.