As the impacts of climate change become more pronounced, Northern Europe and the Baltic regions face growing challenges in developing sustainable and adaptive agricultural practices. Recent years have seen stagnating crop yields alongside increasing negative environmental impacts from intensive agricultural practices.

Monoculture farming methods, which dominate the landscape, are notably less adaptive and resilient to climate stressors. According to the European Commission and supported by consensus among soil scientists, these trends are linked to deteriorating soil quality and carbon stocks – critical factors for European food security.

In response, an interdisciplinary team of experts are investigating how diversified cropping systems can create climate-smart, resilient agriculture systems with net-positive impacts on soil carbon storage. The new research initiative, AgroMixNorth, focuses on enhancing diversity among same species of cereal crops (such as spring barley and oats) with and without intercropping cover crops. These diversified systems are expected to deliver ecological and socio-economic benefits, contributing to climate change mitigation while maintaining – or even improving – crop productivity.

Specifically, AgroMixNorth seeks to:

• Deepen understanding of how plant diversity impacts soil carbon sequestration.
• Evaluate interactions between soil chemistry, biological diversity and soil microbiomes to understand their role in organic carbon processing and storage.
• Assess trade-offs between crop productivity, carbon sequestration and nitrogen cycling.
• Provide farmers and policymakers with tools to future-proof food supply chains while contributing to climate change mitigation.

Globally, soils hold over twice the amount of carbon found in the atmosphere, making them key to the global carbon cycle. The “4 per 1000 Initiative,” launched during COP21 in 2015, advocates for increasing global soil organic carbon stocks by 0.4% annually – a target that could significantly offset human-made greenhouse gas emissions. Diversified cropping systems, such as intercropping and cultivar mixtures, offer the potential to simultaneously enhance below-ground carbon storage and crop performance. However, several trade-offs which need to be addressed.

For example, limited understanding of how root carbon inputs affect nitrogen cycling can lead to increased greenhouse gas emissions, including nitrous oxide which is 300 times more potent than carbon in its warming effects. Additionally, higher carbon inputs from diversified cropping can increase microbial nitrogen demand, reducing the nitrogen available to plants and potentially harming crop yields.

The project is also testing the contributions of multiple intercropping practices, including:

• Relay intercropping: a second crop is planted before the first crop is fully harvested, meaning the two crops overlap in part of their growth cycle.
• Temporal intercropping: crops are planted one after another in the same space but at different times during the growing season.
• Undersowing: a second crop is sown underneath the main crop, usually one that grows quickly or is tolerant of shade.