What is soil respiration and what does it indicate?

• A. The release of CO2 from microbial and root respiration; indicates microbial activity and soil health
• B. The amount of oxygen in the soil
• C. The rate of water infiltration
• D. The color of soil

Answer: (A)

Soil respiration is the CO2 that is released from the soil as microbes break down organic matter and as plant roots respire. This CO2 flux reflects how active the soil food web is—microbes decomposing litter and cycling nutrients, plus roots consuming sugars—so it serves as a direct indicator of microbial activity and overall soil health. Higher respiration generally means active decomposition and carbon turnover, while very low rates can signal drought, compaction, or weak biological activity. It isn’t about how much oxygen is in the soil, how fast water infiltrates, or the soil’s color, which are different properties.