Chunjie Li and coauthors synthesized results of 226 experiments on yield and resource efficiency in intercropping to establish whether or not intercrops on average outperformed the most productive species in a mixture for the production of grain, energy or protein.
The results were published in the Proceedings of the National Academy of Sciences of the United States of America. Outperforming the most productive species in a mixture is called “transgressive overyielding” in the literature. The authors also assessed whether intercrops were more resource use efficient than the most resource use efficient species in the mixture. The results showed that intercrops outperform sole crops when the objective is to achieve a diversity of crop products on a given land area, as characterized by the land equivalent ratio. However, when intercropping is evaluated for its ability to produce raw products without concern for diversity, intercrops on average generate a small loss in grain or calorie yield compared with the most productive sole crop (−4%) but achieve similar or higher protein yield, especially with maize/legume combinations grown at moderate N supply. Overall, although intercropping does not achieve transgressive overyielding on average, the results show that intercropping performs well in producing a diverse set of crop products and performs almost similar to the most productive component sole crop to produce raw products, while improving crop resilience, enhancing ecosystem services, and improving nutrient use efficiency. The study, therefore, confirms the great interest of intercropping for the development of a more sustainable agricultural production, supporting diversified diets.