Nitrogen fixation in annual Trifolium species in alkaline soils as assessed by the ¹⁵N natural abundance method

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dc.contributor.authorDenton, M.
dc.contributor.authorCoventry, D.
dc.contributor.authorBellotti, W.
dc.contributor.authorHowieson, J.
dc.date.issued2011
dc.description.abstractAnnual clover species such as Trifolium purpureum Loisel., T. resupinatum L., and T. alexandrinum L. are adapted to alkaline soil conditions and provide certain agronomic advantages over annual medics (Medicago spp.). Annual clovers have not been widely grown in alkaline soils in Australia, and quantifying their dinitrogen (N₂) fixation in alkaline soils is important in understanding their potential role in mixed farming systems of southern Australia. Using the ¹⁵N natural abundance technique, it was estimated that annual clovers fixed 101–137 kg N/ha at Roseworthy and 59–62 kg N/ha at Mallala, on Calcarosols with soil pH of 8.0 and 8.5, respectively. Species differed in the percentages of fixed N₂ estimated in shoot dry matter, which was highest in T. alexandrinum (77–85%), moderate in T. resupinatum (76%), and lowest in T. purpureum (65–74%). Naturally occurring soil rhizobia (Rhizobium leguminosarum bv. trifolii) provided adequate nodulation, as inoculation with different strains of rhizobia had little influence on nodulation or N₂ fixation. These results indicate that clovers can provide a significant contribution of fixed N₂ to mixed farming systems. Examination of nodules indicated variable nodule occupancy by the inoculant rhizobia and that 69% of shoot N was fixed when clovers were nodulated by the soil populations of rhizobia. A simple model is defined to identify the potential interactions between inoculated legumes and soil rhizobia, and the options for enhancing symbiotic effectiveness are discussed.
dc.description.statementofresponsibilityMatthew D. Denton, David R. Coventry, William D. Bellotti, and John G. Howieson
dc.identifier.citationCrop and Pasture Science, 2011; 62(8):712-720
dc.identifier.doi10.1071/CP11039
dc.identifier.issn1836-0947
dc.identifier.issn1836-5795
dc.identifier.orcidDenton, M. [0000-0002-2804-0384]
dc.identifier.urihttp://hdl.handle.net/2440/67166
dc.language.isoen
dc.publisherCSIRO Publishing
dc.rights© CSIRO 2011
dc.source.urihttps://doi.org/10.1071/cp11039
dc.subjectclover
dc.subjectinoculation
dc.subjectlegume
dc.subjectnodule
dc.subjectrhizobia
dc.subjectRhizobium leguminosarum bv. trifolii
dc.subjectTrifolium alexandrinum
dc.subjectTrifolium purpureum
dc.subjectTrifolium resupinatum.
dc.titleNitrogen fixation in annual Trifolium species in alkaline soils as assessed by the ¹⁵N natural abundance method
dc.title.alternativeNitrogen fixation in annual Trifolium species in alkaline soils as assessed by the (15)N natural abundance method
dc.typeJournal article
pubs.publication-statusPublished

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