The effects of different plantain (Plantago lanceolata) proportions in pasture on gaseous nitrogen loss after urine deposition *

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. The high soil moisture during the experimental period resulted in 48-60% of the applied N being lost through N2 emissions. 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 increase in N2 production with plantain presence was more pronounced in the Allophanic soil than in the Gley soil, which could potentially be attributed to deeper root distribution in the Allophanic soil, which could have further influenced soil denitrification at greater soil depths. However, further information on plantain‘s effect on mineral N at greater depth is needed to better comprehending gaseous N emissions variations.

* Title in Abstracts book: The effect of plantain in pasture swards on gaseous nitrogen emissions from urine patches