Growing more legumes can reduce environment damage

ADDING more legumes, such as beans, peas and lentils, to European crop rotations would deliver higher nutritional value at lower environmental and resource costs, a study has found.

“This strategy can contribute significantly to the specific European Union Green Deal Farm to Fork objectives to reduce greenhouse gas emissions, chemical pesticide use and synthetic fertiliser use,” said study lead author Marcela Porto Costa, of Bangor University.

“For example, in Scotland, we’ve shown that the introduction of a legume crop into the typical rotation reduced external nitrogen requirements by almost half whilst maintaining the same output of food measured in terms of potential human nutrition.”

All crops need the critical nutrient nitrogen in order to grow and, for most crops, farmers must provide nitrogen via fertilisers. However, conventional fertilisers require significant energy to produce, deplete finite resources and can pollute surrounding environment. In contrast to other crop types, legumes are among the only crops that are capable of getting all of the nitrogen they need simply from the air around them, thanks to a symbiotic partnership with bacteria that transforms nitrogen in the air into a form that can be used by plants. As a result, legume crops not only don’t require fertilizer themselves, they also enrich the soil with nitrogen, reducing the need for nitrogen fertilisers for future non-legume crops. From a nutritional perspective, legumes are also one of the most nutrient-rich crops, providing protein, fibre, folate, iron, potassium, magnesium and vitamins. Costa’s new approach is more comprehensive than previous calculations of environmental footprints because it compares 10 different crop sequences using 16 different impact categories.

For in-depth news and views on Scottish agriculture, see Friday’s issue of The Scottish Farmer or visit www. thescottishfarmer.co.uk