A novel framework to study the evolution of crop rotation diversity reveals changes towards regional crop type specialisation in Sweden

Diversification of cropping systems can help decrease the negative environmental impacts of agriculture while increasing ecosystem service benefits to crop production. The crop diversification measure introduced by the 2013 CAP reform aimed to trigger the diversification of cropping systems. There is currently no framework to show how policies that aim to trigger diversification of cropping systems, affect crop rotation diversity at the field scale. In this study, we propose a framework to study the evolution of cropping system diversity, which comprises (1) building crop sequences for two periods using the Geo-spatial Application (GSA) database of the Integrated Administration and Control System (IACS), (2) calculating two indicators of diversity of crop sequences, (3) creating a typology of crop sequences, and (4) determining the significance of change and highlighting drivers of change by using mixed models. Our framework was tested on 1100,760 ha in Sweden, focusing on the periods 2005–2010 and 2011–2016, with four ways of categorizing crops (i.e., crop species, crop types, winter crops vs spring crops, botanical family) in five homogeneous production regions. Using different crop categorization is a way of expressing the robustness of the trends in diversity which account for various relationships among crops. We showed that the value of all diversity indicators in all regions decreased significantly between the two periods, except for the estimated agronomic quality of the crop sequence in the most productive regions where it increased. This general decrease could be explained by longer duration of rotational perennial leys and reduced cultivation of minor cereals, such as rye and oats in the later period. Overall, there was an 8 % increase in ley area, which was particularly evident in regions with less productive land, where the high proportion of ley often became permanent grassland. We found that the trend towards longer duration leys was strong in livestock farms, while regions with productive land favoured the inclusion of more annual cash crops in the rotation, especially oilseed rape, which contributed to the agronomic quality of the sequences. The framework could be widely adopted across Europe using the GSA database of the IACS to track diversification changes at a country and regional level and design appropriate policies to increase the diversity of crop rotations using the potential local drivers highlighted.