Improvement of soil fertility in historical ridge and furrow cultivation

Ridge and furrow cultivation is the most widely used agricultural technique in medieval and postmedieval Europe, but the fertilization of soils during their use is not yet fully understood. Pedological analyses of this cultivation technique provided information, which led to the assumption that some of the investigated sites in Northern and Central Germany were manured with livestock excrements during cultivation. The objective of this study is to determine whether and how the soils have been fertilized and which materials were applied for this purpose. We investigated soils at five sites using phosphate and steroid analyses (stanols and bile acids), black carbon analyses, and a micromorphology study. The results showed that livestock waste was likely used as fertilizer at four of the five studied sites at low intensities, with pigs and herbivores being the probable sources of the excrement. But also the application of human feces to the soil might be possible at least at one site. Often used agricultural methods such as plaggen cultivation and an intentional charcoal input to enhance soil fertility could not be clearly verified for our study sites.