Low and variable: Manuring intensity in Danish Celtic fields

Manuring has often been associated with the emergence of permanent field systems, but manuring practices and intensities are rarely investigated in detail. Previous analyses of phosphorus from Danish Celtic fields show that manuring was carried out at most sites, but due to methodological issues and representativity biases, these results have been difficult to compare and interpret. In this study, samples from three well-preserved field systems in eastern Jutland, Denmark, were analysed with the purpose of investigating the manuring regime. We focused on identifying possible variations between and, in particular, within the individual sites. The main method used was multi-element analysis by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), which was supplemented by soil thin section analysis and analysis of pollen and non-pollen palynomorphs (NPPs). Evidence of animal manure and household waste was found at all three sites and, additionally, material from wetlands was identified at one site. Clear variations between individual fields were identified, which stress the importance of taking composite samples from a large number of fields in order to obtain a more complex understanding of the manuring practices within field systems. Manuring intensity was generally low, indicating a rather extensive use of the field systems in Southern Scandinavia in the Early Iron Age.