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Nitrogen fixation and transfer in grass-clover leys under organic and conventional cropping systems

Oberson, A. ; Frossard, E. ; Bühlmann, C. ; Mayer, J. ; Mäder, P. ; Lüscher, A.

In: Plant and Soil, 2013, vol. 371, no. 1-2, p. 237-255

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    Titel
    • Nitrogen fixation and transfer in grass-clover leys under organic and conventional cropping systems
    Autor
    • Oberson, A.. ETH Zurich, Institute of Agricultural Sciences, Eschikon 33, 8315, Lindau, Switzerland
    • Frossard, E.. ETH Zurich, Institute of Agricultural Sciences, Eschikon 33, 8315, Lindau, Switzerland
    • Bühlmann, C.. ETH Zurich, Institute of Agricultural Sciences, Eschikon 33, 8315, Lindau, Switzerland
    • Mayer, J.. Agroscope Reckenholz-Tänikon Research Station (ART), Reckenholzstrasse 191, 8046, Zurich, Switzerland
    • Mäder, P.. Research Institute of Organic Agriculture (FiBL), Ackerstrasse, 5070, Frick, Switzerland
    • Lüscher, A.. Agroscope Reckenholz-Tänikon Research Station (ART), Reckenholzstrasse 191, 8046, Zurich, Switzerland
    Dokumententyp
    • Postprint
    Sprache
    • Englisch
    Veröffentlicht in
    • Plant and Soil, 2013, vol. 371, no. 1-2, p. 237-255. Springer Netherlands
    Andere elektronische Ausgabe
    OAI-PMH-ID
    • oai:doc.rero.ch:321123
    Summary
    Background and aim: Symbiotic dinitrogen (N2) fixation is the most important external N source in organic systems. Our objective was to compare symbiotic N2 fixation of clover grown in organically and conventionally cropped grass-clover leys, while taking into account nutrient supply gradients. Methods: We studied leys of a 30-year-old field experiment over 2years in order to compare organic and conventional systems at two fertilization levels. Using 15N natural abundance methods, we determined the proportion of N derived from the atmosphere (PNdfa), the amount of Ndfa (ANdfa), and the transfer of clover N to grasses for both red clover (Trifolium pratense L.) and white clover (Trifolium repens L.). Results: In all treatments and both years, PNdfa was high (83 to 91%), indicating that the N2 fixation process is not constrained, even not in the strongly nutrient deficient non-fertilized control treatment. Annual ANdfa in harvested clover biomass ranged from 6 to 16g N m−2. At typical fertilizer input levels, lower sward yield in organic than those in conventional treatments had no effect on ANdfa because of organic treatments had greater clover proportions. In two-year-old leys, on average, 51% of N taken up by grasses was transferred from clover. Conclusion: Both, organically and conventionally cropped grass-clover leys profited from symbiotic N2 fixation, with high PNdfa, and important transfer of clover N to grasses, provided sufficient potassium- and phosphorus-availability to sustain clover biomass production