Effects of Narasin on Nitrogen Turnover and Availability in a Cultivated Sandy Loam

Agricultural soils are exposed to Narasin, an anti-coccidiodal drug, when poultry litter is applied as a nitrogen fertilizer. Though it has a relatively short half-life in soil, narasin may persist at concentrations ranging from pg·kg^-1 to ng·kg^-1. A recent study reported that that exposure in this range affect the composition of soil microbial communities, leading to delayed or modified rates of biogeochemical nitrogen redox reactions. The objective of this experiment was to conduct a comprehensive examination into the effects of 1-1000 ng kg^-1 Narasin nitrogen mineralization, nitrification, and denitrification rates and the resulting impacts on soil N availability and N₂O losses. Soils tested at 40%, 60%, and 80% WFPS showed that ultralow doses of narasin (1-1000 ng kg^-1) can significantly alter one or more steps in the N cycle in ways that may impact N availability to crop plants and increase non-point source N pollution.