Carcass decomposition in the soil can be an important source of nutrients such as nitrogen (N) by affecting N turnover in soils. The objective of this research was to estimate N input from decaying swine carcasses, thereby evaluating the impact of carrion decomposition on N dynamics in soil. Carcass decomposition using recently culled (<6 h) swine carcasses was carried out in a reactor filled with agricultural soil. Soil samples, collected four times (at 0, 10, 30 and 60 days after carcass placement) from the reactor were used in a tracer experiment to quantify the changes in soil nutrients and N dynamics. Tracer incubation experiments were carried out for seven days using 14C-labelled L-alanine (C3H7NO2) to investigate key N cycling processes in the soil. Mortalities were a significant source of N and carbon (C), providing an average of 42 and 236 g/kg, respectively, to the soil directly below the decomposing carcasses. There was also a significant and long-term input of amino acids (ca. 11 mg/kg) into the soil. The abundance of N increased the microbial turnover of labile N substances in the tracer experiment. Based on results from this study, it has been demonstrated that decaying carcasses provide a significant and long-lasting localized resource with the potential to contribute to soil N cycling. Therefore, it is important to develop guidelines on the management of carcass burial farmland using soil from burial pits as a nutrient supplement where biosecurity is assured.