Nodulation Activity

Meet Harlan

This is a lupin root. The large lumps growing on it are called nodules. Nodules are the plant's nitrogen fertiliser factory. There are thousands of rhizobia bacteria living in each nodule, and working busily to make nitrogen fertiliser for the plant.

You can tell if the fertiliser factory is working well just by looking at the colour inside a nodule.

• Go for a walk around your area and find a clover, medic, pea, bean, lupin, chickpea or any other legume plant (remember, they're the plants with pods). Please don't dig up your neighbour's vegetable patch!
• Dig it out of the ground carefully, making sure that you get plenty of the root.

• Wash the soil off the root.
• Look for nodules on the root of your legume - some legumes like clover have very small nodules so you may need to look carefully.
• When you find a nodule, cut it open.
• If the inside is pink or red, the nodule is fixing lots of nitrogen for the plant.
• If the inside is green, the nodule is not a good fertiliser factory for the plant.