International work demonstrates that the incorporation of leaf material from plantain into soil has a significant effect on the nitrogen cycle.
For a period of 28 days nitrate accumulated in soil incubations was lower for soils containing plantain material than the control soils without any plantain material. Secondary plant compounds were suggested as a likely cause of this effect.
Verhagen et al. 1995 reported plantain plant roots suppress nitrification to some extent. Other mechanisms are currently being investigated.
Put simply, research suggests that growing Ecotain environmental plantain modifies the nitrogen cycle in the soil, thus reducing the risk of leaching.
Inhibitory effects of Plantago lanceolata L. on soil N mineralization
Dietz, M., Machill, S., Hoffman, H.C., & Schmidtke, K. (2012)
Competition for ammonium between plant roots and nitrifying and heterotrophic bacteria and the effects of protozoan grazing
Verhagen, F.J.M., Laanbroek, H.J., & Woldendorp, J.W. (1995)