Fewer fertilisers

Making fertiliser is an energy-intensive process. Image: Lynn Graesing/Istockphoto.com

To boost plant growth farmers add chemical fertilisers. It takes lots of energy to make these chemicals, which means that they're expensive and contribute to climate change. Fertilisers added to crops can also damage wildlife – when it rains the excess runs off into lakes and rivers. So scientists are helping farmers find ways to use less fertiliser.

One high-flying idea involves space technology...

I spy...

Henri Douche, agricultural expert, Infoterra. Image: Infoterra

Farmers can get images of their fields beamed down from a satellite. Clever software interprets the images - it can tell if there are enough leaves on the plants or if they look a bit patchy. The software then sends this information to a display inside the farmer's tractor, so the farmer can tell which crops need spraying with fertiliser.

'Using our system means that every drop of fertiliser is put in just the right place, which is better for the farmer and the environment,' says Henri Douche, an agricultural expert from Infoterra.

But there is another way of getting more nitrogen into the soil without using fertilisers...

I'll scratch your back...

Soybeans, like all legumes, have root nodules filled with bacteria, which provide nitrogen for plant growth. Image: US Department of Agriculture

Legumes are plants such as peas and beans that have special bacteria living in their roots.

These bacteria take nitrogen from the air and capture it for the plant to use. In return the bacteria get food and shelter from the plant. The plants and the bacteria both benefit from the partnership.

But how does this help the farmer use less fertiliser?

Side by side

Planting different crops side by side in rows, like this wheat and bean field, is called intercropping. Image: The University of Reading

Mike Gooding at the University of Reading explains: 'Planting crops and legumes in rows makes the best of nitrogen from the air and the soil. If we leave roots in the ground after the crops are harvested it puts nitrogen back into the soil so less fertiliser is needed.'

Wormy compost

A farmer spreading compost made by worms. Image: Practical Action

Researchers at the Food Production Project are helping farmers in Bangladesh replace fertiliser with compost made by worms – vermicompost.

'Local farmers use worms to turn plant waste into compost. This adds nutrients to the soil, so the farms are more productive. It's an inexpensive way to increase food production in some of the poorest areas of the world,' says Neil Noble, a low-tech-development expert from Practical Action.