Does cropping system diversification with legumes lead to higher yield stability? Diverging evidence from long-term experiments across Europe

In the face of climate change and to achieve global food security, the resilience of agricultural systems is gaining increasing attention, and is often considered as important as their productivity (Olesen et al., 2011). Temporal yield stability is one indicator of the economic resilience of cropping systems and its analyses have become more important as a decrease in yield stability has been observed for different crops at regional and global scale (Döring and Reckling, 2018). The temporal and spatial diversification of cropping systems with legumes, perennial crops, cover crops and intercrops can be expected to increase crop yield stability and offers an adaptation strategy to the increased climate variability (Liu et al., 2019). The objectives of this study were to assess the effect of cropping system diversification strategies on yield stability, through (i) integration of perennial leys with and without legumes, (ii) increasing proportion (length, i.e. number of years) of the perennial grass-clover leys relative to the entire crop rotation, (iii) varying the order in which crops are positioned in the rotation, (iv) integration of grain legumes and (v) integration of cover crops during fallow periods