Undersown crops have considerable potential as a climate change adaptation measure, as they provide continuous soil cover. This improves water retention, reduces the risk of erosion, and increases the soil's resilience to extreme weather events, such as heavy rainfall and drought. At the same time, undersown crops effectively absorb soil nitrogen minerals during and after the ripening of the main crop, when other nitrogen sinks in arable soils are largely absent. This nitrogen uptake can significantly reduce nitrous oxide emissions from agricultural soils. Unlike cover crops established after harvest, undersown crops are already established by the time the main crop matures, enabling them to provide an earlier and stronger nitrogen sink.
In order to quantify the climate mitigation potential of undersown crops, this project will systematically monitor soil mineral nitrogen and nitrous oxide emissions from the time of crop maturity until approximately six weeks after the undersown crop has been incorporated. On two commercial farms with contrasting soil types (light and heavy), two mixtures of undersown crops will be sown into winter wheat at two different times (autumn and spring). In the control treatment without undersowing, a green manure crop will be established after the wheat harvest. From autumn 2026 onwards, the field experiments will also include agronomic and soil physical assessments, enabling a comprehensive evaluation of the use of undersown crops as a measure for adapting to and mitigating climate change.
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