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 (700 kg ha⁻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 (47 kg ha⁻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