SCOTTISH farmers could reduce fertiliser use, lower their environmental impact and improve barley yields by introducing field beans into their crop rotations, according to new research.
A long-term study by scientists at the James Hutton Institute, working alongside the University of Galway, has found that growing field beans before spring barley can deliver significant benefits for both agricultural productivity and the environment.
The research, carried out using data from the institute’s Centre for Sustainable Cropping at Balruddery Farm near Dundee, compared barley grown after field beans with barley grown following another barley crop.
Scientists found that growing beans before barley reduced the environmental impact of barley production by around 25 per cent on average, while also cutting the amount of synthetic nitrogen fertiliser required.
Across five two-year cropping periods, fertiliser use for barley following beans was reduced by an average of 22kg per hectare.
The researchers also identified potential improvements in crop yields, with barley grown after beans producing an average of 1.2 tonnes per hectare more than barley grown after barley in four of the five years studied.
The findings could be particularly significant for Scotland’s agricultural sector, where spring barley plays a vital role in supplying the brewing, whisky distilling and livestock industries.
Field beans are legumes, meaning they work with naturally occurring soil bacteria to obtain nitrogen from the atmosphere, removing the need for synthetic nitrogen fertiliser during their cultivation.
They can also leave behind nitrogen in the soil, benefiting the crops grown in subsequent seasons.
Dr Cathy Hawes, who leads research at the Centre for Sustainable Cropping, said the findings demonstrated the longer-term advantages of more sustainable farming practices.
“The CSC was established to test what genuinely regenerative cropping can look like in practice,” she said.
“Rather than relying on a single intervention, CSC stacks a series of complementary innovations including reduced tillage, organic matter inputs, cover and companion cropping, more targeted pesticide use, nutrient budgeting and biodiversity-supporting field features.”
She explained that the aim was to maintain productive farming while reducing reliance on external inputs and improving soil health, biodiversity and environmental performance.
“These results show that the benefits of that approach can carry from one crop into the next, rather than being confined to a single growing season,” she added.
However, researchers cautioned that introducing field beans does not automatically guarantee higher yields.
During the unusually dry conditions associated with the 2022 barley crop, barley grown after beans actually produced lower yields than barley following barley.
The study found that weather conditions, particularly temperature and humidity, alongside the performance of the preceding bean crop, could significantly influence the benefits.
Professor Pietro Iannetta, co-author of the study, said the research highlighted the importance of assessing farming practices over several growing seasons rather than examining individual crops in isolation.
“This is an important study because there are still relatively few life-cycle assessments that look properly at crop sequences,” he said.
“That matters because regenerative agriculture is fundamentally about system function across time.”
He added that further research would examine whether reductions in fertiliser and pesticide use were accompanied by measurable improvements in soil processes, nutrient cycling and biodiversity.
The study, published in the scientific journal Plant and Soil, also explored the potential national benefits of adopting bean–barley crop rotations more widely.
Researchers suggested that greater use of these rotations could help reduce greenhouse gas emissions from Scottish agriculture, although further testing across different farms, soil types and growing conditions would be needed.
The findings offer a potential route towards more sustainable cereal production, allowing farmers to reduce their reliance on synthetic fertilisers while maintaining, and potentially improving, crop yields.
