Microbes like Rhizobium, Nitrosomonas and Nitrobacter are used for:

Explanation:

Rhizobium, Nitrosomonas, and Nitrobacter are microorganisms involved in the nitrogen cycle.

• Rhizobium fixes atmospheric nitrogen into the soil in the root nodules of leguminous plants.
• Nitrosomonas converts ammonia (NH₃) into nitrite (NO₂⁻).
• Nitrobacter converts nitrite (NO₂⁻) into nitrate (NO₃⁻), which plants can absorb.

Therefore, these microbes play an important role in the nitrogen cycle.

Correct Answer: Nitrogen cycling / नाइट्रोजन चक्र