Crop rotations including ley and manure can promote ecosystem services in conventional farming systems

Agricultural intensification has contributed substantially to the increase in food production, but has come at the expense of soil degradation and environmental problems. Management of soil based ecosystem services need to be considered in agricultural management since intensive management implies not only costs to the farmer but also to society. In this study we used data from four long-term (55 years) agricultural experiments in southern Sweden to assess the effects of two arable farming systems on a range of indicators of soil ecosystem services. One farming system used only annual commodity crops (ACC system) while the other integrated one year of ley (ley system) into the crop rotation. Nitrogen (N) fertiliser was applied annually in both farming systems at two rates (0 and 150kgNha^-1). The ley farming system had an addition of farmyard manure (FYM) once every fourth year. Soil organic carbon, total N, phosphorous, potassium, pH and water holding capacity were used as indicators of regulating services; bacterial and fungal biomass were used as indicators of supporting services; grain yield and protein content were used as indicators of provisioning services. We analysed each of the indicators separately, to identify effects of the farming systems, using linear mixed effects models. In addition, we used principal components analysis to bundle the individual indicators together to create latent variables representing categories of ecosystem services. Yields of wheat were greatest in the plots that received N fertiliser, irrespective of farming system, while mycorrhizal fungal biomass was greatest in the ley system with no inorganic N fertiliser. The rest of the indicators were similar in both farming systems although the lowest values of all ecosystem service indicators were found in the ACC system with no N fertiliser. When bundling the indicators, no trade-offs were found between regulating, supporting and provisioning services. Regulating and supporting services were positively correlated, as were regulating and provisioning services. The ley system with N fertiliser had significantly greater values of regulating and provisioning services relative to the other treatments. The results indicate that different farming systems can have large effects on ecosystem service flows, and that integrating leys into arable rotations can enhance the delivery of soil ecosystem services.