The biochemical alteration of soil beneath a decomposing carcass

The processes associated with cadaver decomposition in outdoor settings, particularly those that occur during the extended postmortem interval (>30 days) are poorly understood. Thus, few methods are currently available to accurately estimate the extended postmortem interval (PMI). Of these methods, a soils-based approach has the potential to address the postmortem interval between which entomology and anthropology are the most valuable. Although the validity of soil-based methods has previously been established, little work has been conducted to explain the processes that have been designated for forensic application. As a consequence, we investigated the dynamics of carbon, nitrogen, and phosphorus-based compounds in soil beneath pig (Sus scrofa) cadavers (gravesoil) that were placed on the soil surface over a period of 100 days. Decomposition was assessed through the physical characteristics of the cadaver, soil pH, soil moisture content, and the concentration of total carbon, total nitrogen, soil-extractable phosphorus, and lipid-phosphorus in soil. Cadaver decomposition did not result in a significant difference in soil carbon and moisture content. However, significant (P<0.05) increases were observed in the concentration of soil pH, total nitrogen, soil-extractable phosphorus, and lipid-phosphorus. Based on the current results, a significant increase in the concentration of gravesoil nutrients represented a maximum PMI of 43 days (lipid-P), 72 days (total nitrogen), or 100 days (soil-extractable phosphorus). This work provides further evidence that a soil-based method has the potential to act as a tool for the estimation of extended PMI.