Meta-analysis of the effects of undersown catch crops on nitrogen leaching loss and grain yields in the Nordic countries

Summary

This meta-analysis synthesises evidence from field experiments across the Nordic countries to assess whether undersown catch crops — typically grasses or legumes established beneath a main cereal crop — can meaningfully reduce nitrogen leaching without penalising grain yields. The study likely reports a statistically significant reduction in nitrogen leaching associated with catch crop use, alongside a relatively modest or neutral effect on main-crop grain yield. By pooling data across sites and countries, it provides regionally relevant effect sizes to inform agronomic and environmental policy recommendations.

UK applicability

The Nordic climate — characterised by cool temperatures, autumn rainfall surplus, and comparable cereal-based rotations — is broadly analogous to upland and northern UK conditions, making the findings reasonably transferable to Scotland, northern England, and parts of Wales. The results are relevant to UK catchment-sensitive farming schemes and nitrate vulnerable zone (NVZ) management requirements under the Farming Rules for Water.

Key measures

Nitrogen leaching loss (kg N/ha or % reduction); grain yield (t/ha or relative yield); catch crop biomass and nitrogen uptake where reported

Outcomes reported

The study quantified the effect of undersown catch crops on nitrate nitrogen leaching losses and grain yields of the main cereal crop, synthesising results across multiple field experiments in Nordic conditions.

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