Do sward age and pasture renewal affect the potential of plantain (Plantago lanceolata) to reduce N2O emissions from urine patches?

Abstract Plantain ( Plantago lanceolata ) has shown the potential to reduce nitrous oxide (N 2 O) emissions from urine patches. However, inconsistent results have been reported in previous studies. In this context, the sward age might be a factor regulating plantain effectiveness in mitigating N 2 O emissions. Thus, this study aimed to assess the effect of sward age on N 2 O emissions from urine patches under different sward composition ratios of ryegrass/white clover (RG/WC) and plantain (PL). We also examined the potential impact on N 2 O emissions of transitioning a RG/WC based pasture to PL swards. Two field experiments were undertaken to: (i) compare N 2 O emission from urine applied to 2-year (Old plantain) and 3-month (New plantain) old swards with sowing densities aiming at four proportions of PL mixed with RG/WC (0; 30; 45 and 100% PL) and (ii) assess N 2 O emissions during soil cultivation and sowing following transition from RG/WC to PL swards. New plantain tended to decrease N 2 O emissions from urine patches by ~ 31% relative to RG/WC pastures, but this effect was significant only in the 45% PL. In contrast, there were no significant effects of the Old plantain sward, probably because of increased clover biomass relative to the new sward. In addition, the transition from RG/WC pasture to PL swards increased N 2 O emissions from 0.1 to 1.53 kg N ha −1 . Finally, our results suggest that plantain’s inhibitory effect on N 2 O emissions from cattle urine is more effective in a 3-month-old sward than a 2-year-old sward. However, it was not possible to disentangle effects of sward age and clover share in the sward in this study. Pasture renewal increased N 2 O emissions, and therefore, other approaches to renew swards should be considered to minimize N 2 O emissions.