Soil chemical analysis supports the identification of ancient breeding structures: The case-study of Cà Tron (Venice, Italy)

Analyses of the phosphorus (P), carbon (C) and nitrogen (N) content of the soil, together with elemental ratios, were applied to the archaeological area of Cà Tron (Venice, Italy), where Roman farms exploited the countryside from the I to the V century BP. Two different methods, ignition (i) and hydrolysis with perchloric acid (h) were used to determine the total P (TP) content and their reliability is discussed. Results showed very high values in both iTP and hTP in the site. High inorganic P (IP) contents were found just along the walls of the building giving evidence for the mineralization of organic P (OP) which was entrapped into inorganic with the calcium carbonate and thus preserved. Among the elemental ratios, the organic C/total C (OC/TC) and C/N highlighted for a organic matter from animal and not from vegetable origin, whereas the OC/OP and N/OP confirmed for the anthropogenic origin of the site. All these results strongly support for the identification of the remains of a Roman rural building as a stable for bred cattle.