[MIS25-01] Competition for inorganic-N between soil microbes and plants?
Keywords:Nitrogen dynamics, Stable isotope, inorganic nitrogen
In this talk, I will present our new δ15N data of plants, soil nitrogen, and SMB in the forested ecosystems in Japan which illustrates that δ15N of SMB was totally different from δ15N of plants. δ15N of SMB was higher than δ15N of other N, i.e. bulk soil N, extractable organic and inorganic N, and plants. Since δ15N of SMB is controlled by the balance of N assimilation and N excretion (Collins et al. 2008; Shinoda et al. 2018), the higher δ15N of SMB is attributed to the soil N assimilation with N excretion (N mineralization). In other words, SMB utilized soil organic N with N mineralization. Since δ15N of plants shows the plant’s reliance on soil inorganic nitrogen, it is likely that there was no obvious competition for nitrogen between SMB (utilizing organic nitrogen) and plants (utilizing inorganic nitrogen). This is my quite preliminary data interpretation and I look forward to the discussion on our δ15N data in the talk.