Farming during turbulent times: Agriculture, food crops, and manuring practices in Bronze Age to Viking Age Denmark

•Charred plant remains show an increase in food resources in Iron Age Denmark.•Stable isotopes show consistent soil enrichment in fields of barley.•Agriculture seems resilient to climatic fluctuations during the Iron Age. Archaeobotanical and stable isotope analysis on plant remains from 39 sites spanning the Bronze, Iron, and Viking Ages in Denmark has been undertaken in order to investigate the development and resilience of agricultural practices, particularly through the 1250-year-long Iron Age (500 BC – AD 750). During this time, an increase in the spectrum of food resources can be seen in the archaeobotanical material. At the same time, soil enrichment of fields of barley, which increased markedly during the Bronze−Iron Age transition, remains consistent until the Viking Age. A more broad-spectrum diet appears to tie in with agricultural extensification comprising increased scales of land use and fallowing alongside possibly less intense tillage of fields. These practices appear to have made agriculture resilient to climatic fluctuations during our study period, with the possible exception of a shift following volcanic eruptions in AD 536/540.