Effect of carbon and nitrogen mobilization from livestock mortalities on nitrogen dynamics in soil

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.