A review of supporting evidence, limitations and challenges of using cover crops in agricultural systems

Cover crops are becoming widely integrated into many farms as tools for improving sustainability. However, the decisions by growers for planting follow several objectives/criteria, many of which overlap. This review orders these sowing rationales into a practical framework for land management guidance. Prioritised by cover crop performance objectives, the optimal species and their environmental requirements are discussed. A key consideration of this review is that cover crops are used as part of a rotation strategy. Here, farmers’ primary objectives are to maintain or enhance biomass not of the cover plants themselves but for the following commercial crop. For example, a large cover crop biomass may be beneficial for reducing field-nutrient losses but are counterproductive if nutrient immobilisation or offtake then results in subsequent nutrition stresses and yield declines. Furthermore, species selection and management practices must be integrated if these negative impacts are to be mitigated. This review has found a strong research focus on cover crop nitrogen dynamics but limited research on nutrient recycling more broadly. Moreover, there is growing evidence that regionality plays a critical role in cover crop and land management partnering due to variations in edaphic and climatic influences, but there is a shortfall in research to inform strategies for many important agricultural centres such as Northern Ireland.