abstract
Addition of P, Co or Mo solutions, separately or together, to peat samples from an oligotrophic mire at Marion Island (46°54' S, 37°45' E) did not significantly increase acetylene reduction rates over those exhibited by samples to which an equal amount of distilled water was added. Addition of glucose, with or without P, Co and/or Mo, markedly enhanced acetylene reduction rates. It is concluded that readily utilizable energy sources limit N fixation in the mire peat but the possibility that inorganic nutrients might be secondarily limiting could not be discounted.