title: Long-term agricultural fertilization alters arbuscular mycorrhizal fungal community composition and barley (Hordeum vulgare) mycorrhizal carbon and phosphorus exchange.
abstract: Agricultural fertilization significantly affects arbuscular mycorrhizal fungal (AMF) community composition. However, the functional implications of community shifts are unknown, limiting understanding of the role of AMF in agriculture. We assessed AMF community composition at four sites managed under the same nitrogen (N) and phosphorus (P) fertilizer regimes for 55 yr. We also established a glasshouse experiment with the same soils to investigate AMF-barley (Hordeum vulgare) nutrient exchange, using carbon (13C) and33P isotopic labelling. N fertilization affected AMF community composition, reducing diversity; P had no effect. In the glasshouse, AMF contribution to plant P declined with P fertilization, but was unaffected by N. Barley C allocation to AMF also declined with P fertilization. As N fertilization increased, C allocation to AMF per unit of P exchanged increased. This occurred with and without P fertilization, and was concomitant with reduced barley biomass. AMF community composition showed no relationship with glasshouse experiment results. The results indicate that plants can reduce C allocation to AMF in response to P fertilization. Under N fertilization, plants allocate an increasing amount of C to AMF and receive relatively less P. This suggests an alteration in the terms of P-C exchange under N fertilization regardless of soil P status.
authors.affiliation: Centre for Environmental and Climate Research, Lund University, Lund, SE-223 62, Sweden.
authors.forename: Alwyn
authors.initials: A
authors.lastname: Williams
authors.affiliation: Department of Biology, Lund University, Lund, SE-223 62, Sweden.
authors.forename: Lokeshwaran
authors.initials: L
authors.lastname: Manoharan
authors.affiliation: Centre for Environmental and Climate Research, Lund University, Lund, SE-223 62, Sweden.|Department of Biology, Lund University, Lund, SE-223 62, Sweden.
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Rosenstock
authors.affiliation: Department of Biology, Lund University, Lund, SE-223 62, Sweden.
authors.forename: Pål Axel
authors.initials: PA
authors.lastname: Olsson
authors.affiliation: Department of Biology, Lund University, Lund, SE-223 62, Sweden.
authors.forename: Katarina
authors.initials: K
authors.lastname: Hedlund
mesh_terms: D000383:Agriculture; D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D005308:Fertilizers / Q000009:adverse effects*; D005658:Fungi / Q000502:physiology*; D001467:Hordeum / Q000382:microbiology*; D038821:Mycorrhizae / Q000502:physiology*; D010758:Phosphorus / Q000378:metabolism*; D018520:Plant Shoots / Q000378:metabolism
chemical_list: D005308:Fertilizers; D010758:Phosphorus; D002244:Carbon
keywords: agriculture; arbuscular mycorrhizal fungi (AMF); carbon (C); diversity; fertilizer; mutualism; nitrogen (N); phosphorus (P)