fix atmospheric nitrogen
Fix atmospheric nitrogen means changing nitrogen gas (N2) from the air into nitrogen compounds that plants can absorb and use.
- Even though air is about 78% nitrogen, plants cannot use nitrogen gas directly because it is very stable and does not react easily.
- Certain bacteria (like Rhizobium) can “unlock” this nitrogen by converting it into useful forms such as ammonia and then nitrates, which plants can take up through their roots.
- This matters because nitrogen is needed to make proteins and chlorophyll (important for growth and photosynthesis). Without enough usable nitrogen, plants grow weak and pale.
- In legume plants (peas, beans, lentils), Rhizobium lives in root nodules—a partnership where the plant gives the bacteria food and shelter, and the bacteria supplies usable nitrogen.
- Think of it like a natural fertiliser factory attached to the roots: it helps the soil become richer, so fewer chemical fertilisers are needed.
That’s why growing legumes in between other crops can naturally improve soil fertility for the next crop.