Transfer of symbiotically fixed nitrogen in an alfalfa-grass mixture studied through isotope dilution in a pot experiment.
The nitrogen transfer between alfalfa and ryegrass was studied through isotope dilution at three different levels of N fertilization (20 mg N/pot, 200 mg N/pot, 400 mg N/pot) in a pot experiment using quartz sand as a substrate. An isogenic, nodulating, but non nitrogen fixing alfalfa line was used as a reference crop. Fixed N was transferred to the grass in the 20 mg N treatment and contributed markedly to the N nutrition of the grass (about 50% of the N in the plants). No transfer of fixed N could be detected in the higher fertilized treatments, although nitrogen fixation was only slightly inhibited by the presence of the fertilized mineral N. It is concluded that N transfer is strongly influenced by the N concentration in the substrate and transferred N contributes only slightly to the productivity of the legume/grass mixture under the given experimental conditions.
Beschow
H
H
Institut für Bodenkunde und Pflanzenernährung, Landwirtschaftliche Fakultät der Martin-Luther-Universität Halle-Wittenberg, Germany.
Schulze
J
J
Merbach
W
W
D005308:Fertilizers; D006801:Humans; D007201:Indicator Dilution Techniques; D000455:Medicago sativa / Q000378:metabolism*; D009584:Nitrogen / Q000737:chemistry / Q000493:pharmacokinetics*; D009586:Nitrogen Fixation; D009587:Nitrogen Isotopes
D005308:Fertilizers; D009587:Nitrogen Isotopes; D009584:Nitrogen