The effect of plantain (Plantago lanceolata L.) in pasture swards on gaseous nitrogen emissions from nitrogen-enriched urine patches

Plantain has been shown to possess biological nitrification inhibiting (BNI) activity, which can reduce nitrous oxide (N₂O) emissions from ruminant urine patches. However, the effectiveness of plantain in mitigating these emissions remains unclear.

In this study, the ¹⁵N flux method was employed to investigate the relationship between different plantain proportions in pasture sward and gaseous nitrogen (N) ((N₂O and dinitrogen (N₂)) loss following dairy cow urine deposition (660 kg N ha^-1) on the Allophanic and Gley soils.

The findings indicate that the presence of plantain reduced cumulative N₂O emissions after urine deposition, but there was no direct correlation between the nominal sowing rate and its mitigation effectiveness. However, in the Allophanic soil, there was a reduction in cumulative N₂O emissions with an increase in the proportion of plantain in the dry matter. Plantain presence increased total N₂ emissions in both soil types, possibly due to its BNI function, which would retain mineral N in the soil for an extended period, providing substrate for complete denitrification. The total N₂ emissions from the Allophanic soil with plantain presence were higher compared to those from the Gley soil.

This study revealed the role of soil type in the effect of plantain on N₂O and N₂ emissions from urine patches. The increase of proportion of plantain in the pasture dry matter in the Allophanic soil decreased cumulative N₂O emissions, while no effect of plantain proportion was observed in the Gley soil.