Nitrogen-trapping roots
Bacteria in bean roots help the plant.
Lumps on the roots
The roots of beans, peas and lentils have small swollen lumps called nodules. Farmers grow these plants in rotation with other crops.
What do you think lives inside the lumps?
What this lesson covers
The idea
Rhizobium bacteria live in swollen root nodules of legumes such as beans, peas and lentils, where they trap nitrogen from the air and make it useful for the plants.
Lumps on the roots
The roots of beans, peas and lentils have small swollen lumps called nodules. Farmers grow these plants in rotation with other crops.
What do you think lives inside the lumps?
- Helpful bacteria
- Only soil
- Nothing at all
Look at a bean plant
Tap the three views, one by one.
Bacteria that help plants
Rhizobium bacteria live in the swollen root nodules of legumes such as beans, peas and lentils. They trap nitrogen from the air and make it useful for the plants.
So plants grow better without chemical fertilisers. That is why farmers grow legumes in rotation with other crops: it naturally increases the nitrogen in the soil and keeps it healthy for the next crop.
- Part | What it is
- Legumes | Beans, peas and lentils
- Root nodule | A swollen region of the root
- Rhizobium | Bacteria that live in the nodule
- Their job | Trap nitrogen from the air and make it useful for the plant
Notes
Rhizobium bacteria live in the swollen root nodules of legumes such as beans, peas and lentils, and trap nitrogen from the air, making it useful for the plants.
Check yourself
Where do Rhizobium bacteria live?
What do Rhizobium trap from the air?
Why do farmers grow legumes in rotation with other crops?
- In the root nodules of legumes — correct. Yes. Nodules are swollen regions of the roots of beans, peas and lentils.
- In the leaves of every plant. Rhizobium live in the root nodules of legumes.
- In the sky. Rhizobium live in the roots. They trap nitrogen from the air.
- Nitrogen — correct. Yes. They make it useful for the plants.
- Methane. Methane is in biogas. Rhizobium trap nitrogen.
- Alcohol. Alcohol is made by yeast. Rhizobium trap nitrogen from the air.
- It naturally increases the nitrogen in the soil and keeps it healthy for the next crop — correct. Yes. Rhizobium in the root nodules make nitrogen useful for plants.
- Legumes have no roots. Legumes have roots, and the roots have nodules.
- To stop microbes living in the soil. The microbes in the nodules help the plants and the soil.