Differences in growth features between species are driving cereal-legume intercrop yield: A statistical learning approach based on aggregated dataset

Increasing crop diversification is crucial for developing more sustainable agricultural systems, and cereal-legume intercropping is a promising strategy. This study investigates the factors influencing the yield of cereal-legume intercrops using data from six field experiments in southwestern France, where durum wheat was intercropped with either faba bean or pea. We assessed how differences in plant traits ( e.g. , height or biomass growth rates) between the associated species were related to the intercrop productivity. Additionally, we developed a novel modeling approach, combining machine learning and mixed-effects models, to identify the key drivers of intercrop performance based on variable importance. Our results showed that interspecific differences in plant traits within intercrops, particularly in biomass accumulation rate, maximum leaf area index, and elongation rates, were the most important factors explaining intercrop yield. These traits and their differences mainly suggest that competitive processes shape the outcome of a mixture and highlight the importance of dynamic measurements in agronomic experiments. The relationship between species yield and trait differences was symmetric for both intercropped species. Furthermore, these relationships were scale-dependent, with trends observed at the aggregate level not always consistent at the level of individual experiments. Our study highlights the importance of considering trade-offs when designing intercropping systems for practical applications and demonstrates the value of combining machine learning with ecological knowledge to gain insights into complex agricultural systems from aggregated datasets. • Joint analysis of experimental datasets provided new insights into crop mixtures functioning. • Differences in growth traits between species within the mixture explained their performance. • The strength of the correlation between performance and trait differences was similar for both species. • Farmers and researchers need to consider trade-offs when designing intercropping systems.