Manuring practices in the first millennium AD in southern Sweden inferred from isotopic analysis of crop remains

Abstract

This study uses crop stable nitrogen isotope analysis of charred grain to explore manuring practices in arable production at the affluent regional center Uppåkra and a set of smaller surrounding sites, dating to the first millennium AD in southern Sweden. The isotopic analysis focuses on hulled barley, the principle crop in the Scandinavian Iron Age, and the minor crops: bread wheat, emmer wheat, rye and oat, are included to compare manuring practices in cultivation of other crop species during this period. A field experiment was first conducted to establish relationships between manuring and δ 15 N values in modern grain from known growing conditions. The data formed an interpretive framework to reconstruct past agricultural practices and manuring intensity in the archaeological study area. Our results from the ancient grains have demonstrated that barley from the early phase in the study area (AD 0–200) varies widely in its δ 15 N values, reflecting mixed manuring regimes. In the following periods (AD 200–1000), isotopic values are relatively high overall, indicating systematic input of manure. In this paper, we explore whether the isotopic data that indicates sustained and high manuring levels could reflect the wealth of Uppåkra and its surrounding areas by showing prosperity also in its agricultural production, since intensive manuring would have required more resource and labor investments. The new crop nitrogen isotopic data shed light on the agricultural practices of a long-lived Iron Age center and its surrounding areas.

Movement of agricultural products in the Scandinavian Iron Age during the first millennium AD: 87Sr/86Sr values of archaeological crops and animals in southern Sweden

“…A recently published compilation and modeling of pollen data shows that the fertile soils of southwestern Scania during the Iron Age were characterized by a very open, almost treeless landscape, and that arable land covered c. 20-35% of the land area (Lagerås and Fredh 2019). Another recent study determined nitrogen isotope values of archaeological cereal grains recovered from Uppåkra and six nearby sites (Larsson, Bergman, and Lagerås 2019). Larsson, Bergman, and Lagerås (2019) found that the grains had high nitrogen isotope values and attributed these to systematic addition of manure to arable fields during most of the first millennium AD.…”

“…Another recent study determined nitrogen isotope values of archaeological cereal grains recovered from Uppåkra and six nearby sites (Larsson, Bergman, and Lagerås 2019). Larsson, Bergman, and Lagerås (2019) found that the grains had high nitrogen isotope values and attributed these to systematic addition of manure to arable fields during most of the first millennium AD. These studies both point to intensive crop production in the area, and for that reason, it seems unlikely that farmers in the investigated area had the need to import large quantities of grain from regions outside.…”

Uppåkra. A Central Site in South Scandinavian Iron Age

“…There was evidence to indicate the latter, but excavation uncovered additional dome-shaped clay ovens. Analyses of charred grains found at one of the ovens show that it was used to dry the mash for brewing beer (M. Larsson et al 2018;2019b). This suggests the allocation of a part of the settlement area for making beer over several centuries.…”

“…By comparison with other samples in Uppåkra, these are of a somewhat larger dimension, refl ecting sorted grains from crop-processing activities. The long-term trend of crop cultivation on manured soils, evidenced from high δ 15 N values in grain, signals agricultural wealth in the area and this pairs with the economic affl uence that is ascribed to the regional center Uppåkra (M. Larsson et al 2019b). Flax and gold of pleasure were grown, mainly for oil production.…”

How Does Diet Influence Our Lives? Evaluating the Relationship between Isotopic Signatures and Mortality Patterns in Italian Roman Imperial and Medieval Periods

“…Within the terrestrial ecosystem, it can distinguish C 3 from C 4 plant sources; on the other hand, the nitrogen isotopic signature (δ 15 N) is useful for determining the trophic level of the analyzed individual(s) [ 1 , 2 , 18 , 19 ]. It would be worth analyzing coeval plant and animal specimens along with human samples in order to better interpret the ecological context and to evaluate possible variations of the isotopic values due to specific agriculture and breeding practices, and/or to the analyzed sites’ geographical location and ecology [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ].…”