The evolution of Central German Chernozems/Phaeozems since the Early Bronze Age between natural soil alteration and human overprinting

Black-colored humus-rich Chernozems and closely related Phaeozems are among the most fertile soils of the world, and were often used for agriculture over several millennia. The westernmost continuous Chernozem/Phaeozem region of Eurasia is located in the in the eastern lee of the Harz Mountains in Central Germany with precipitation < 550 mm/a. Unlike in other regions of Central Europe with anthropogenic Chernozems/Phaeozems, their formation can be related to natural factors such as high carbonate contents of their loose parent material and a dry subcontinental climate, suggested to foster appropriate living conditions for anecic earthworms. Their formation started prior to regional Neolithic settlement at latest during the early Holocene, and lasted until about 6-5 ka when the regional climate became more humid. Since that time, Chernozems/Phaeozems were subject to decalcification, clay translocation, silicate weathering and clay formation processes. The Central German Chernozem/Phaeozem region was used for agriculture for several millennia, with a strong intensification since the end of the 19th century. Furthermore, this region has also intensively been industrialized since that time, including widespread lignite burning in large power plants. However, only one study investigated a Late Neolithic buried Chernozem in comparison with the neighboring surficial soil using a limited amount of laboratory analytics, so that natural and anthropogenic changes of Central German Chernozems/Phaeozems during the last millennia were not systematically studied so far.

To fill this gap, we systematically compared the properties of a Chernozem that was buried by the Early Bronze Age burial mound Bornhöck ca. 3.8 ka ago, and was consequently largely preserved from subsequent soil forming processes and human influence, with those of a neighboring Chernozem/Phaeozem that was continuously exposed to natural and human processes until today. The goal of our study was to systematically identify differences in the properties of the two soils, allowing an exemplary assessment of the property changes of Chernozems/Phaeozems due to soil alteration and human overprinting in an intensively agriculturally and industrially used region during the last 3.8 ka.