Spatial and genetic crop diversity support ecosystem service delivery: A case of yield and biocontrol in Dutch organic cabbage production

Summary

A single focus on yield in agroecosystems comes at the expense of other ecosystem services, for instance, biocontrol of pests. In this study, we investigated the potential of intercropping to improve the delivery of ecosystem services by cropping systems. Intercropping was expected to deliver a higher yield through facilitation and complementarity while simultaneously suppressing pests via pest habitat dilution and habitat provision for natural enemies. Utilizing a network of experiments on crop diversification with different spatial arrangements and different levels of genetic crop diversity across the Netherlands in 2018, we analyzed the effect of seven intercropping designs on crop injury by pests, yield and quality in cabbage. Individual cabbage leaf injury by herbivorous pests was assessed using a newly developed diagrammatic scale. Provisioning services were measured as individual cabbage fresh weight and yield per unit area. We found a significant negative relationship between crop diversity and herbivore feeding injury per cabbage: intercropping designs with more species, accessions and/or cultivars exhibited lower feeding injury. The presence of flower strips significantly reduced overall injury in the adjacent cabbage strip, despite higher injury found in the rows closer to the flower strip. There was no clear relationship between crop diversity and fresh marketable weight per cabbage, however five out of seven intercropping designs were able to maintain total yield per area when compared with the sole crop reference. Our results show that crop diversification can simultaneously support the production ecosystem service by maintaining fresh marketable weight per cabbage plant and productivity per unit area, as well as the regulating ecosystem service of pest control. These results provide a basis for redesigning large-scale arable fields into diversified productive systems, and thereby facilitate the transition towards more sustainable farming systems. A better understanding of crop functionality and management needs in diverse arrangements is relevant for such redesign.