Crop Residue Removal for Bioenergy Could Put Farmland Biodiversity at Risk

European research links higher cereal residue retention with greater local biodiversity, highlighting a trade-off between renewable energy production and field management.

The stems, leaves and husks left after cereal harvests could help meet Europe’s demand for renewable energy. However, new research suggests that taking more of these materials from fields could put farmland biodiversity under pressure.

A study led by the University of Surrey found that cereal-growing areas retaining at least 70% of crop residues generally supported greater local biodiversity than areas where less remained. Residue retention was also a stronger predictor of biodiversity than crop yield, highlighting the importance of post-harvest management.

The findings could inform assessments of how much cereal residue can sustainably be diverted to bioenergy.

Crop Residues Serve Multiple Purposes

Residues from crops such as wheat and corn already supply some fuel and bioenergy production. They also provide animal feed and bedding, while material left in fields helps maintain healthy soils and supplies food and habitats for wildlife.

As Europe seeks to increase renewable energy production, researchers at Surrey worked with the Natural History Museum’s Biodiversity Futures Lab and Utrecht University to investigate how residue retention relates to local biodiversity.

The study, published in Agriculture, Ecosystems and Environment, used statistical models to analyse biodiversity measurements across European land uses, including cereal fields, alongside information on crop yields, residue management and environmental conditions.

Higher Retention Linked to Greater Biodiversity

The findings suggest that increasing residue removal could have consequences for farmland wildlife, particularly in areas where farmers currently leave a high proportion in place.

“Crop residues could provide a valuable source of renewable energy for Europe’s green transition, but as with any natural resource, we need to fully understand what happens if we take more of these materials from fields. Our findings suggest that there could indeed be consequences for biodiversity, and that needs to be factored in when assessing how much crop residue can sustainably be used for bioenergy production,” said Professor Zoe M. Harris, director of the Centre for Environment and Sustainability at the University of Surrey.

The relationship identified by the models highlights the need to consider residue management alongside crop productivity when assessing bioenergy supplies. Further research is needed to establish how removing residues directly affects biodiversity, according to a press release.

Existing Uses Could Offer Another Supply Route

The researchers also identified a potential alternative to taking more material from fields: reducing the amount of crop residue used for animal feed and bedding could make more available for bioenergy.

“It’s not just about finding enough material to produce renewable energy, but working out where that material should come from. Rather than removing more crop residues from fields, we should also be looking at how they’re used elsewhere, including in animal production. There may be opportunities to make more of this material available for bioenergy without putting additional pressure on farmland and the wildlife it supports,” said lead author Dr. Sophie Tudge.

Tudge carried out the research during her PhD at Surrey and is now a postdoctoral researcher at the University of Leeds.

Balancing Energy Demand and Field Management

The study highlights the competing demands placed on cereal residues and the need to account for their role in agricultural ecosystems when planning renewable energy production.

It also points to broader challenges, including protecting natural habitats from agricultural expansion. Further investigation of residue removal could help identify bioenergy supply options that support Europe’s energy ambitions while protecting farmland biodiversity.