Soil tillage drives multifunctionality in the onset of a diversified cropping system

Intensified agricultural production with cereal-dominated crop rotations and high fertiliser and pesticide inputs, often combined with inversion tillage, degrades cropping system multifunctionality. Cropping system diversification via integration of service crops, increasing the functional diversity of crops in the rotation as well as reduced tillage has been suggested to enhance agroecosystem multifunctionality. However, evidence is predominantly based on assessment of single practices and single agroecosystem functions, leaving their combined effects on cropping system multifunctionality poorly understood. Here, we assess cropping system multifunctionality in a Swedish cropping system diversification trial based on 15 indicators of soil physical health, nutrient capture and cycling, natural weed and pest regulation, and macronutrient output collected during the first three years under contrasting diversification strategies (crop rotation diversification, service crop use, and tillage reduction). Using a combined index of diversification practices, we found that high diversification was associated with compacted soils, more soil detritivores and fewer crop pests, likely mainly driven by the implementation of tillage reduction. The combined index masked many practice-related effects: tillage reduction was most influential for cropping system multifunctionality, followed by increased crop rotation diversity, whereas the inclusion of service crops did not affect any indicators. Several indicators were interrelated and affected by the same diversification practice, highlighting the complex dependencies in agroecosystems. Despite multiple benefits, we also identified diversification-related trade-offs: tillage reduction benefited pest regulation but increased soil compaction and hampered weed regulation, while increased crop rotation diversity reduced nitrogen inputs but also lowered weed regulation and metabolisable energy output. Our results emphasise that cropping system diversification is a promising pathway to sustainable agriculture yielding various benefits for cropping system multifunctionality when trade-offs are managed.