Plant and Soil

, Volume 175, Issue 1, pp 57–66 | Cite as

Estimates of seasonal nitrogen fixation of annual subterranean clover-based pastures using the15N natural abundance technique

  • T. P. Bolger
  • J. S. Pate
  • M. J. Unkovich
  • N. C. Turner
Research Article

Abstract

Annual pasture legumes play a key role in ley farming systems of southern Australia, providing biologically fixed nitrogen (N) to drive the production of the pastures as well as subsequent crops grown in rotation. Seasonal inputs of biologically fixed N in shoot biomass of the subterranean clover (Trifolium subterraneum) component of grazed annual pastures were assessed using the15N natural abundance technique and appropriately timed sampling of herbage dry matter (DM) for N accumulation. At three study sites spanning a gradient across the Western Australian wheatbelt from 300 to 600 mm annual rainfall the performance of the clover and non-legume herbs and grasses was examined as paired comparisons involving two management treatments expected to give contrasting effects on pasture productivity, botanical composition and N2 fixation. The proportion of clover N derived from atmospheric N2 fixation (%Ndfa) ranged from 65 to 95% across sites, treatments and sampling times. Amounts of fixed N accumulated in clover shoot biomass ranged from 50 to 125 kg ha−1, and paralleled trends in clover production. Substantial increases in pasture production in high yielding treatments generally occurred without decrease in %Ndfa, suggesting that N2 fixation was essentially non-limiting to performance of the clover component. Seasonal profiles for accumulation of fixed N were skewed towards the late winter and spring period, particularly in low plant density pastures following a cereal crop. There were seasonal, site and treatment-specific effects on the proportion of clover and non-legume pasture components and consequently clover yield and N2 fixation were variably affected by competition from non-legume species.

Key words

competition crop rotation farming systems ley farming soil nitrogen Trifolium subterraneum 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Bergersen F J and Turner G L 1983 An evaluation of15N methods forestimating nitrogen fixation in a subterranean clover-perennial ryegrass sward. Aust. J. Agric. Res. 34, 391–401.CrossRefGoogle Scholar
  2. Brink G E 1990 Seasonal dry matter, nitrogen, and dinitrogen fixation patterns of crimson and subterranean clovers. Crop Sci. 30, 1115–1118.Google Scholar
  3. Butler J H A 1988 Growth and N2 fixation by field grownMedicago littoralis in response to added nitrate and competition fromLolium multiflorum. Soil Biol. Biochem. 20, 863–868.CrossRefGoogle Scholar
  4. Carter E D, Porter R G, Ababneh M H, Sequella F, Muyekho F N and Valizadeh R 1992 The production and management of annual legumes in ley farming systems of South Australia.In Proc. 6th Australian Agronomy Conference. pp 418–421. The Australian Society of Agronomy, Parkville, Victoria.Google Scholar
  5. Cavell A J 1954 A rapid method for the determination of nitrogen, phosphorus and potassium in plant materials. J. Sci. Food Agric. 5, 195–200.Google Scholar
  6. Donald C M 1951 Competition among pasture plants. I. Intra-specific competition among annual pasture plants. Aust. J. Agric. Res. 2, 355–376.Google Scholar
  7. Ledgard S F, Simpson J R, Freney J R and Bergersen F J 1985 Field evaluation of15N techniques for estimating nitrogen fixation in legume-grass associations. Aust. J. Agric. Res. 36, 247–258.Google Scholar
  8. Ledgard S F and Steele K W 1992 Biological nitrogen fixation in mixed legume/grass pastures. Plant and Soil 141, 137–153.CrossRefGoogle Scholar
  9. McQuaker N R, Brown D F and Kluckner P D 1979 Digestion of environmental materials for analysis by inductively coupled plasma-atomic emission spectrometry. Anal. Chem. 51, 1082–1084.Google Scholar
  10. Milliken G A and Johnson D E 1984 Analysis of Messy Data. Vol. 1: Designed Experiments. Van Nostrand Reinhold, New York. 473p.Google Scholar
  11. Pate J S, Unkovich M J, Armstrong E L. and Sanford P 1994 Selection of reference plants for15N natural abundance assessment of N2 fixation by crop and pasture legumes in south-west Australia. Aust. J. Agric. Res. 45, 133–147.CrossRefGoogle Scholar
  12. Peoples M B, Brockwell J and Bergersen F J 1992 Factors affecting nitrogen fixation: scope for improvement?In Transfer of Biologically Fixed Nitrogen to Wheat. Ed. J FAngus. pp 21–32. Grains Research and Development Corporation, Canberra, Australia.Google Scholar
  13. Puckridge D W and French R J 1983 The annual legume pasture in cereal-ley farming systems of southern Australia: A review. Agric. Ecosys. Environ. 9, 229–267.CrossRefGoogle Scholar
  14. Robson A D 1983 Mineral nutrition.In Nitrogen Fixation. Vol. 3. Legumes. Ed. W JGroughton. pp 36–55. Clarendon Press, Oxford, UK.Google Scholar
  15. Robson A D 1990 The role of self-regenerating pasture in rotation with cereals in Mediterranean areas.In The Role of Legumes in the Farming Systems of the Mediterranean Areas. Eds. A EOsman, M HIbrahim and M AJones. pp 217–236. Kluwer Academic Publishers, Dordrecht.Google Scholar
  16. Rossiter R C 1959 The influence of maturity grading on total yield and seed production in strains ofTrifolium subterraneum L. grown as single plants and in swards. Aust. J. Agric. Res. 10, 305–321.CrossRefGoogle Scholar
  17. Rossiter R C 1966 Ecology of the Mediterranean annual-type pasture. Adv. Agron. 18, 1–57.Google Scholar
  18. Sanford P, Pate J S and Unkovich M J 1994 A survey of the proportional dependence of subterranean clover and other pasture legumes on N2 fixation in south-west Australia utilizing15N natural abundance. Aust. J. Agric. Res. 45, 165–181.CrossRefGoogle Scholar
  19. Shearer G and Kohl D H 1986 N2-fixation in field settings: estimations based on natural15N abundance. Aust. J. Plant Physiol. 13, 699–756.Google Scholar
  20. Sweeney R A and Rexroad P R 1987 Comparison of LECO FP-228 “Nitrogen Determinator” with AOAC copper catalyst Kjeldahl method for crude protein. J. Assoc. Off. Anal. Chem. 70, 1027–1031.Google Scholar
  21. Thomson C J, Ewing M A, Turner N C, Revell C K and LeCoultre I F 1995 Pasture age and timing of germinating rains influence the productivity and botanical composition of subterranean cloverbased annual pastures grown in rotation with wheat. Aust. J. Agric. Res. (In press).Google Scholar
  22. Unkovich M, Pate J S and Sanford P 1993 Preparation of plant samples for high precision nitrogen isotope ratio analysis. Commun. Soil Sci. Plant Anal. 24, 2093–2106.Google Scholar
  23. Unkovich M J, Pate J S, Sanford P and Armstrong E L 1994 Potential precision of the δ15N natural abundance method in field estimates of nitrogen fixation by crop and pasture legumes in south-west Australia. Aust. J. Agric. Res. 45, 119–132.Google Scholar

Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • T. P. Bolger
    • 1
  • J. S. Pate
    • 2
  • M. J. Unkovich
    • 2
  • N. C. Turner
    • 1
  1. 1.CSIRO Division of Plant IndustryWembleyAustralia
  2. 2.Botany Department and Centre for Legumes in Mediterranean AgricultureUniversity of Western AustraliaNedlandsAustralia

Personalised recommendations