What is the role of legumes in crop rotation and soil fertility?

• A. Legumes fix atmospheric nitrogen through symbiotic bacteria, enriching soil nitrogen for subsequent crops.
• B. Legumes deplete soil nitrogen.
• C. Legumes do not affect soil fertility.
• D. Legumes only provide forage.

Answer: (A)

Legumes in crop rotation enhance soil fertility by fixing atmospheric nitrogen through symbiotic bacteria in their root nodules. This partnership, usually with Rhizobium bacteria, converts nitrogen gas from the air into ammonia, a form plants can use. When the legume grows and then residues decompose, much of that fixed nitrogen becomes available in the soil, increasing the nitrogen supply for subsequent crops. This helps reduce the need for synthetic nitrogen fertilizers and supports better yields for the following non-legume crops in the rotation. While some legumes are grown for forage or other uses, their standout soil fertility role is the nitrogen fixation and its contribution to the soil nitrogen pool.