Pollinators, pests and soil properties interactively shape oilseed rape yield

Abstract

Pollination, pest control, and soil properties are well known to affect agricultural production. These factors might interactively shape crop yield, but most studies focus on only one of these factors at a time. We used 15 winter oilseed rape (Brassica napus L.) fields in Sweden to study how variation among fields in pollinator visitation rates, pollen beetle attack rates and soil properties (soil texture, pH and organic carbon) interactively determined crop yield. The fields were embedded in a landscape gradient with contrasting proportions of arable and semi-natural land. In general, pollinator visitation and pest levels were negatively correlated and varied independently of soil properties. This may reflect that above- and below-ground processes react at landscape and local spatial scales, respectively. The above-ground biotic interactions and below-ground abiotic factors interactively affected crop yield. Pollinator visitation was the strongest predictor positively associated with yield. High soil pH also benefited yield, but only at lower pest loads. Surprisingly, high pest loads increased the pollinator benefits for yield. Implementing management plans at different spatial scales can create synergies among above- and below-ground ecosystem processes, but both scales are needed given that different processes react at different spatial scales.