Potential inhibition of urine patch nitrous oxide emissions by Plantago lanceolata and its metabolite aucubin

Plantain (Plantago lanceolata L.), a forage used in grazed pastures, contains active secondary metabolites that could potentially inhibit nitrification, a key step in nitrous oxide (N2O) production from grazing ruminant livestock urine patches. A field study was performed to determine the effects of aucubin, a secondary metabolite in plantain, on nitrification and soil N2O emissions under a ruminant urine patch. Soils were treated with bovine urine (700kgha(-1)) and either a plantain leaf extract (PLE), which contained all extractable compounds in plantain including aucubin, or an aucubin solution (AS). PLE and AS were applied at the same rate of aucubin (47kgha(-1)). N2O emissions were reduced by 50% and 70% in the PLE and AS treatments, respectively; however, there were no significant differences in soil inorganic nitrogen concentrations when urine was applied with PLE or AS.