Field Beans Cut Fertiliser Use, Boost Barley Yield
Long-term study reveals environmental benefits and productivity gains for cereal rotations
Long-term research from The James Hutton Institute, working with the University of Galway, has demonstrated that incorporating field beans into cereal rotations can reduce fertiliser use, lower environmental impacts, and in most years studied, increase the yield of the subsequent barley crop.
Scientists analysed data from the Hutton’s Centre for Sustainable Cropping (CSC) at Balruddery Farm near Dundee for the study, published in Plant and Soil, which found that synthetic nitrogen fertiliser use for barley following beans was reduced by an average of 22 kg per hectare.
Environmental impacts across the crop sequences were reduced by around 25%, and spring barley following beans yielded an average of 1.2 tonnes per hectare more than barley following barley in four of the five years examined.
Dr Cathy Hawes, who leads research at the CSC, explained the centre’s approach. She said: “The CSC was established to test what genuinely regenerative cropping can look like in practice.
“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 with the aim of maintaining productive farming while reducing reliance on external inputs and improving soil condition, biodiversity and wider environmental performance over the long term. 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.”
The significant reason for these findings is biologically derived nitrogen, as field beans are legumes that work with naturally occurring soil bacteria to obtain nitrogen from the atmosphere. This eliminates the need for synthetic nitrogen fertiliser for the beans themselves and leaves a useful nitrogen legacy for the following crop. The study also noted that pesticide use, another major contributor to the environmental footprint of crops, can be substantially lower after field beans.
While a productivity benefit was observed in most cases, researchers cautioned that beans are not an automatic guarantee of higher yields. In the unusually dry conditions of the 2022 barley crop, barley following beans yielded less than barley following barley. The study suggested that weather, particularly temperature and humidity, along with the performance of the preceding bean crop, strongly influences the benefit received by the subsequent cereal.
Professor Pietro Iannetta, a co-author of the study, highlighted the importance of this research. He said: “This is an important study because there are still relatively few life-cycle assessments that look properly at crop sequences. That matters because regenerative agriculture is fundamentally about system function across time. The next challenge is to go beyond measuring impact reduction alone and ask whether those reductions are matched by real gains in ecosystem functions, including soil processes, nutrient cycling and biodiversity.”
He added that further advanced life cycle analysis (LCA) work is underway at the CSC to link reductions in environmental burdens with measured changes in ecosystem functioning, aiming to demonstrate genuinely regenerative outcomes.
The findings hold particular relevance for Scotland, where spring barley supports major brewing, distilling, and livestock industries. A theoretical scaling exercise within the paper estimated that wider adoption of bean–barley sequences could offer substantial greenhouse-gas reductions, although the authors emphasised that this national estimate requires further testing across diverse soils, farms, and seasons.
