What is the function of root nodules in legumes?

Root nodules in legumes serve a crucial function of fixing atmospheric nitrogen, which is essential for plant growth. These nodules are a result of a symbiotic relationship between legume plants and nitrogen-fixing bacteria, primarily from the genus Rhizobium. When legumes engage with these bacteria, they provide a suitable environment for them to thrive, while the bacteria convert nitrogen gas from the atmosphere into a form (ammonia) that the plant can utilize for synthesizing proteins and other vital compounds.

This process significantly contributes to the nutrient content of the soil, enhancing its fertility and benefiting not only the legume itself but also surrounding plants when the legume decomposes or when its root nodules release nitrogen into the soil. This self-sustaining cycle allows legumes to thrive in nitrogen-deficient soils and is a key reason why legumes are often used in crop rotations and sustainable agriculture practices to improve soil health.