title: Use of 15N-enriched soil to study N2 fixation in grasses.
mesh_terms: D001419:Bacteria / Q000378:metabolism; D007553:Isotope Labeling / Q000379:methods; D009586:Nitrogen Fixation; D009587:Nitrogen Isotopes; D010944:Plants / Q000378:metabolism*; D006109:Poaceae / Q000378:metabolism; D013559:Symbiosis
chemical_list: D009587:Nitrogen Isotopes