What does nitrogen fixing mean?

Nitrogen fixation is the process by which nitrogen changes into an available and useful form for the plant.

The plants draws nitrogen from the air and converts it into a form that can be stored in their roots. Legume plants like fava beans do this with the help of nitrogen-fixing bacteria that live on their root nodules.

While the plant is growing, it holds the converted nitrogen in its roots. But as soon as the plant dies, it’s released into the soil. It can now be used by other plants. Nitrogen is essential for plant growth, so nitrogen fixers are hugely helpful to farmers and gardeners alike.

Why is nitrogen important?

All plants need nitrogen to grow and reproduce successfully. They use it to manufacture amino acids, proteins, nucleic acids and other components necessary for life. Without nitrogen, they simply can’t survive.

Because of its critical role in plant health, farmers often add nitrogen to the soil in the form of artificial fertilisers. Great on paper, but in practice excess fertiliser often runs off fields - negatively affecting our waterways and wildlife.

The manufacture of artificial fertiliser also contributes significantly to UK greenhouse gas emissions. This makes it unsustainable long-term.

Fava beans as nitrogen fixers

Fava beans are one of the world’s most powerful nitrogen fixers. Once they have flowered and produced beans, the fava bean plant then releases nitrogen into the soil as it dies back. This process naturally enriches the soil, providing food and energy for the next crop of plants.

By adding more nitrogen to the soil than they take out, fava beans not only enrich the soil - they also eliminate the need for artificial fertilisers, making them a hugely sustainable crop to grow.