Agricultural diversification often promotes biodiversity and ecosystem services by increasing habitat diversity. However, responses to agricultural diversification are context dependent, differentially impacting functional groups of service-providing organisms and crop yields. Conservation and no tillage are promoted as agricultural diversification practices that increase soil heterogeneity and habitat diversity. Here we investigated whether soil tillage practices in canola crop fields altered arthropod biodiversity or yield, and how effects of field-scale diversification compared to landscape-scale habitat context. We focused on effects of high, medium, or no tillage on five functional groups with unique diets and reproductive strategies: (i) herbivores, (ii) kleptoparasites, (iii) parasitoids, (iv) pollinators, and (v) predators. Effects of agricultural diversification on arthropod abundance and diversity varied across functional groups. Pollinators responded to on-farm soil diversification, benefiting from medium tillage. Predators and herbivores responded most strongly to landscape-scale habitat composition and were more abundant in landscapes with more semi-natural habitat. However, variation in arthropod communities had little effect on canola crop yield, which was lowest in fields with no tillage. Policy implications: Our results indicate that natural history differences among arthropod functional groups mediate how habitat availability affects biodiversity. Crop yields, however, showed no response to biodiversity of ecosystem service providers. Our research highlights the need to determine the contexts in which soil diversification practices meet a multi-faceted goal of simultaneously supporting natural biodiversity, ecosystem services, and crop yield.
Differential effects of soil-based agricultural diversification on arthropods and crop yield