Lipid biomarkers of manuring practice in relict anthropogenic soils

Abstract

This investigation tests the extent to which free soil lipids reflect known manuring practices associated with a relict twelfth-to nineteenth-century anthropogenic deep top soil in West Mainland Orkney. The results demonstrate that total lipid extracts reflect the expected spatial variability in manuring intensity across the deep top soil area, declining with distance from the farmstead. Specific organic manure inputs are also identified; the presence of campesterol, sitosterol and 5β-stigmastanol confirm expected composted turf and ruminant animal manure application to the deep top soil area. A departure from the expected results is the presence of coprostanol, reflecting omnivorous animal manure deposition and confirmed as pig manure through the identification of hyodeoxycholic acid. These analyses establish that lipid biomarkers of past land-management activity are retained in medieval to early modern relict landscapes, and that they allow more precise identification of manure sources and patterns of deposition than conventional pedological techniques. Further, they suggest that historic documentation forms only a partial record of manuring practices