An Agroecology Use Case in the ORKG: A mini-review on how legume intercrops affect cereal grain yields

Increasing on-farm biodiversity by growing two or more types of crops together (i.e., intercropping) has the potential to provide multiple benefits, including increased crop yield. This comparison looks at the yield effects of intercropping legumes—plants that make atmospheric nitrogen available to other plants—with cereal crops. The original aim of the comparison was to focus on European studies that evaluate how intercropping legumes with cereal crops affects cereal crop grain yield relative to cereal crop monocultures, cropping systems where individuals of the same crop species are planted together. However, the regional focus on Europe was expanded slightly to include one additional study conducted in Canada (and published in a European journal), as the original literature search yielded relatively few usable scientific articles (described below). The goal of this comparison is to provide an agroecology use case in the ORKG that demonstrates the utility of this platform for scoping articles in the field of ecology, rather than to conduct a robust synthesis on the topic of legume intercrops.

The original search for scientific articles was conducted in Web of Science and included the following search terms: "legum* intercrop*" OR "legum* polyculture" AND ("grain yield" OR "cereal yield" OR "grain productivity" OR "cereal productivity" OR "grain biomass" OR "cereal biomass") AND (effective* OR performance* OR assessment* OR evaluation* OR estimate* OR comparison* OR contrast*) AND Europe*. This search was conducted in October 2022 and yielded 34 articles. Selected articles include those that were either open access or accessible through the University of Leibniz, Hannover Technical Information Library, and that provided information on cereal crop yields in the text or in tables; data presented in figures or plots that required extraction were not included in this comparison. Data from four papers met these eligibility criteria and were included in the comparison.