The arbuscular mycorrhizal symbiosis links N mineralization to plant demand.
Arbuscular mycorrhizal (AM) fungi facilitate inorganic N (NH(4)(+) or NO(3)(-)) uptake by plants, but their role in N mobilization from organic sources is unclear. We hypothesized that arbuscular mycorrhizae enhance the ability of a plant to use organic residues (ORs) as a source of N. This was tested under controlled glasshouse conditions by burying a patch of OR in soil separated by 20-microm nylon mesh so that only fungal hyphae can pass through it. The fate of the N contained in the OR patch, as influenced by Glomus claroideum, Glomus clarum, or Glomus intraradices over 24 weeks, was determined using (15)N as a tracer. AM fungal species enhanced N mineralization from OR to different levels. N recovery and translocation to Russian wild rye by hyphae reached 25% of mineralized N in G. clarum, which was most effective despite its smaller extraradical development in soil. Mobilization of N by G. clarum relieved plant N deficiency and enhanced plant growth. We show that AM hyphae modify soil functioning by linking plant growth to N mineralization from OR. AM species enhance N mineralization differentially leading to species-specific changes in the quality of the soil environment (soil C-to-N ratio) and structure of the soil microbial community.
Atul-Nayyar
A
A
Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, P.O. Box 1030, 1 Airport Rd., Swift Current, Saskatchewan, S9H 3X2, Canada.|Department of Soil Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8, Canada.
Hamel
C
C
Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, P.O. Box 1030, 1 Airport Rd., Swift Current, Saskatchewan, S9H 3X2, Canada. hamelc@agr.gc.ca.|Department of Soil Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8, Canada. hamelc@agr.gc.ca.
Hanson
K
K
Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, P.O. Box 1030, 1 Airport Rd., Swift Current, Saskatchewan, S9H 3X2, Canada.
Germida
J
J
Department of Soil Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8, Canada.
D018533:Biomass; D038821:Mycorrhizae / Q000254:growth & development / Q000502:physiology*; D009584:Nitrogen / Q000378:metabolism*; D018517:Plant Roots / Q000382:microbiology; D006109:Poaceae / Q000378:metabolism / Q000502:physiology*; D012988:Soil Microbiology; D013559:Symbiosis
D009584:Nitrogen