Present-day soil distribution explained by prehistoric land-use: Podzol–Arenosol variation in an ancient woodland in Denmark

Abstract

Archaeological evidence has rarely been used by soil scientists to explain the distribution of present-day soils, yet recent human influence is known to be important for all soils. Sites with abandoned prehistoric fields are commonly found throughout western Europe but the impact on present-day soils is not fully known. The studied site, Alstrup Krat, is an intact Bronze and Iron Age site with a well-preserved system of fields (infields) and common areas (common). It was abandoned around 2000 BP and has been beech wood since. This paper concerns the connection between the present-day soil distribution and this former land-use. The methods used in the field were soil survey, intensive ditching, and profile descriptions, and these were combined with soil physical and chemical laboratory analyses (texture, OC, N, P, Fe, Al, optical density on oxalate extracts [ODOE], and base ions). This revealed two distinct soil types whose borders coincided with the prehistoric common/infield border on the dominant parent material—sandy and gravelly tills. Hyperdystric Arenosols are found in the infields and Haplic Podzols in the common area. Entic Podzols or Spodic Arenosols are developed in the common/infield transition zone and in infields that were furthest from the dwellings during cultivation. Podzols had been expected in the infields, as Iron Age agriculture is believed to have exhausted the soil and caused podzolization. Chemical and physical differences between infields and the common area did not explain the observed soil distribution. The only difference between the two adjacent areas was prehistoric land-use until 2000 years ago. The main factor is probably agriculture during the Iron Age, which physically rejuvenated the soil in the infields. Archaeological information thus provided a powerful tool for explaining soil spatial distribution where standard soil science variables and methods would have failed.