Manuring and land exploitation in the Central Plains of late Longshan (2200–1900 BCE) China: Implications of stable isotopes of archaeobotanical remains

Abstract

The Central Plains of China is ideal for studying the interplay between agricultural production and social complexity. Focusing on four sites (Wangchenggang, Chengyao, Wadian, and Xinzhai) dating to the Late Longshan (2200–1900 BCE) in the Central Plains, the present study described species identification results of charred crop seeds at each site and then carried out carbon and nitrogen stable isotope analyses of 55 samples consisting of 456 cereal grains and soybeans. Our results suggest the different landforms were exploited in the Central Plains during the Late Longshan period, with foxtail millet (Setaria italica), common millet (Panicum miliaceum), rice (Oryza sativa), and soybean (Glycine max) being favorably cultivated in lands with different geographic features. We also propose the practice of millet and rice manure in the region. Furthermore, the inhabitants at centralized settlements such as Wadian seemed to have differed in their ability to procure and consume the better-manured millets and rice, an indication that crop foods and social status may be intertwined. While the implications of our isotopic study are constrained by the small sample size, our data are broadly compatible with the hypothesis that the diversified agricultural system contributes to the formation of institutionalized inequality. Further work and research directions are also highlighted.