Climate change should make it possible to grow soya bean profitably in the UK, as far north as the Scottish border by 2050, according to a new study from the UK’s Rothamsted Research.
UK agriculture would greatly benefit from an economically viable, nitrogen-fixing legume such as soya, says Kevin Coleman, an ag scientist at Rothamsted Research in Harpenden. ‘It would also break the pest, competitor or disease cycles in the main cash crops that dominate current rotations.’
The researchers carried out three years of field trials, starting in 2016, growing up to a dozen different soya bean varieties on two sites (Science of the Total Environment, 2021, 767, 144903). Modelling then used simulated weather data and two emissions scenarios to predict, now and in future, whether soya bean would mature across the UK.
‘Soya bean could be included as a rotation crop, before a winter crop is planted,’ says Coleman. ‘It would diversify cropping in the UK.’ He notes that most soya varieties have been bred for warmer temperatures in South America and southern US.
An estimated 3.8m t of soya bean are consumed in the UK, including soya beans and meal for livestock, and another 0.7m t are included in other products. Only modest amounts are grown in Europe, with most imported from the US and South America.
Soya UK, which supplies seeds to UK growers, says that soya can be grown in southern England and Wales and there is increasing demand for the crop. Soya protein offers an alternative to animal-based protein, and the plant fixes nitrogen, so reducing the need for fertiliser additions.
Mean yield during the field trials was 1.7t/ha, which compares with an average global yield of 2.8 and European average yield of 2t/ha. No fertiliser was added to the Rothamsted crop.
Plant scientist Christine Foyer at the University of Birmingham, UK, describes the research as ‘exciting,’ because ‘it provides information that will be of use to farmers and governments in years to come’.
She says it is remarkable that soya bean could be a profitable crop as far as the Scottish border by 2050, even without any genetic improvements. ‘Soya bean was originally a temperate crop, but years of breeding have been for warmer climates and much more sunlight,’ explains Foyer. ‘The wild relatives have enormous potential to bring in traits that would allow it to be better suited to grow under UK conditions.’
This, she believes, could deliver ‘much better yields’ than predicted in the research paper.
There is huge interest in the UK, Ireland and Europe to become less dependent on imports of soya bean from North and South America. Soya bean could also be considered in intercropping systems, mixing it with other crops, where it could usefully apply nitrogen to the soil and so reduce inputs of costly fertiliser, Foyer adds.
‘A lot of farmers don’t grow legume crops at the moment because there is no incentive from government,’ says Foyer. She believes soya bean could be incentivised in future in mixed cropping systems, because it would reduce agrichemical inputs, while also reducing emissions.
For now, the field trials did highlight some potential challenges in growing soya in the UK. ‘Some of the soya bean didn’t mature until mid-November [after being planted in April],’ says Coleman. This could pose a problem because soya would ideally need to be harvested by early October to allow in-field drying and to give farmers enough time to prepare the ground for winter wheat, which is a widely grown and profitable crop in the UK.