Legumes could be the secret ingredient for sustainable farming

14 Apr 2021

Legumes. Image: University of Limerick

University of Limerick research says bringing the nitrogen-enriching effects of legumes to European crop rotations could pave the way for more sustainable farming.

Adding legumes such as peas, beans, lentils and chickpeas to European crop rotations could be the answer to more sustainable farming practices in Europe, according to a new study that involved research from the University of Limerick.

The research, published in Frontiers in Sustainable Food Systems, claims that adding legumes to traditional crop rotations, which typically include barley, wheat and rapeseed, could have significant environment benefits and offer greater nutritional value for humans and livestock.

The conventional fertilisers used by most farmers can be harmful to the environment. But for a long time, they have been the only way farmers could provide their crops with nitrogen, which is a critical nutrient for growth. Producing these fertilisers requires large amounts of energy and they deplete finite resources while also polluting the surroundings.

This is where legumes differ. Due to a symbiotic relationship with bacteria, they can get all the nitrogen they need simply from the air around them. This means that legumes don’t need fertilisers, but that they also enrich the soil around them with nitrogen that can reduce the need for harmful fertilisers for other non-legume crops in the future.

Legumes are also one of the most nutrient-rich crops, according to the researchers, providing protein, folate, fibre, potassium, magnesium, iron and vitamins.

The study’s lead researcher was Dr David Styles, a member of the Bernal Institute at University of Limerick, where he is also a lecturer in environmental engineering.

“Our innovative approach goes beyond simple food footprints by looking at the footprint of delivering a specific quantity of human, or livestock, nutrition from all crops produced within representative crop rotations,” Styles said.

“This provides a clearer picture of inter-crop effects and the overall efficiency of different cropping sequences in delivering nutritious food, or livestock feed.

“Our results strengthen evidence on the positive role that healthy diet transitions could make to environmental sustainability. Legumes provide a healthier balance of carbohydrates, protein and fibre compared with cereal crops, and could improve the nutritional profile of the food we eat.”

The paper’s first author, Marcela Porto Costa of Bangor University, said that this strategy could significantly impact the EU’s Farm to Fork strategy, which aims to reduce greenhouse gas emissions and use of chemical pesticides and synthetic fertilisers.

The study looked at a timeframe of three to five years for the proposed crop rotation in three different European climates across Italy, Romania and Scotland.

Lisa Ardill was careers editor at Silicon Republic until June 2021