Which statement is true about the role of bacteria in soils?

• A. Rapid nutrient cycling
• B. Slow erosion
• C. Heat production
• D. Water repellence

Answer: (A)

Bacteria in soils drive rapid nutrient cycling by breaking down organic matter and mineralizing nutrients, making them available for plant uptake. They perform key processes such as nitrogen fixation, nitrification, ammonification, and phosphate solubilization, which quickly convert organic and unavailable forms into inorganic nutrients that plants can use. This rapid nutrient release supports plant growth, especially in ecosystems like rangelands where inputs can be variable.

Erosion timing and rate are governed mainly by physical factors—wind, water, soil cover, and texture—rather than by bacterial activity. Heat production is not a dominant feature of soils under normal conditions; it becomes noticeable mainly in compost piles with intense microbial activity. Water repellence arises more from soil organic coatings and texture than from bacterial action, though microbes can influence soil structure indirectly. So, the primary role of soil bacteria is speeding up nutrient cycling.