Manure for millet: Grain δ15N values as indicators of prehistoric cropping intensity of Panicum miliaceum and Setaria italica

Broomcorn and foxtail millet are the only major domesticated plants indigenous to prehistoric Eurasia rely on C4photosynthetic pathway. Here we study impact of animal manure (AM) broomcorn (Panicum miliaceum) (Setaria italica), grown in Askov Long-Term Experiment, using unmanured soil dressed with phosphorus plus potassium (PK) as reference treatments. Animal had a marked effect yields δ15N values grains. For millets manured soil, average value was 5.8‰. When PK-treated soils, were 0.4‰ 0.2‰, respectively. also differed between grains from (-1.0‰), PK (0.7‰) (6.3‰) Thus, when compared offset due 7.3‰ for Setaria 5.3‰ two Panicum varieties. In accordance previous studies C3 crops, our suggests that charred recovered archaeological sites could provide robust indicator manuring intensity.