Phosphorus-efficient pastures: legume root traits for improved nutrient foraging

R. Haling, Z. Yang, N. Shadwell, R. Simpson, R. Culvenor, A. Stefanski, G. Sandral, Daniel Kidd, Hans Lambers, Megan Ryan

Research output: Chapter in Book/Conference paperConference paperpeer-review


The critical soil phosphorus (P) requirement (P supply for 90% maximum yield) of many temperate pastures is determined by the high P requirements of key pasture legumes (commonly Trifolium or Medicago spp.). Legumes that yield well with a lower critical P requirement could reduce the fertiliser requirement of these pastures. Pot experiments were used to: (i) identify legumes with root traits likely to confer P acquisition efficiency, and (ii) test the impact of these traits on critical P requirement. An initial screen of the root hair length (RHL)
and specific root length (SRL) of 13 legumes and two grasses was undertaken. Growth and root morphology of five legumes (Trifolium subterraneum, T. hirtum, Ornithopus sativus, O. compressus, Biserrula pelecinus) and one grass (Dactylis glomerata) were subsequently compared in detail using a sandy loam soil (8.3 mg/kg Colwell P) that was amended by applying P to the top 5 cm of the soil profile (0, 15, 30, 70, 135, 250 mg P/ kg). Shoot and root growth were assessed after six weeks.
Significant variation in RHL (0.12-0.75 mm) and SRL (98-603 m/g) was found among the legumes, with most being substantially shorter (RHL) or lower (SRL) than the grasses. In the P-response experiment, Ornithopus species (the only legumes with RHL and SRL approaching that of the grasses) had critical P
requirements that were less than half that of T. subterraneum. Selecting legumes that maximise root foraging via long, thin roots with long root hairs may reduce the critical P requirement of pastures.
Original languageEnglish
Title of host publicationBuilding Productive, Diverse and Sustainable Landscapes
Subtitle of host publicationProceedings of the 17th Australian Agronomy
Place of PublicationAustralia
PublisherAustralian Society of Agronomy Inc.
Pages1 - 4
Number of pages4
ISBN (Print)9780646952246
Publication statusPublished - 2015
Event17th Australian Agronomy Conference - Australia
Duration: 20 Sep 201524 Sep 2015


Conference17th Australian Agronomy Conference


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