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Soil acidity and nutrient deficiency cause poor legume nodulation in the permanent pasture and mixed farming zones of south-eastern Australia

Hackney, B.F., Jenkins, J., Powells, J., Edwards, C.E., De Meyer, S., Howieson, J.G., Yates, R.J. and Orgill, S.E. (2019) Soil acidity and nutrient deficiency cause poor legume nodulation in the permanent pasture and mixed farming zones of south-eastern Australia. Crop and Pasture Science, 70 (12). p. 1128.

Link to Published Version: https://doi.org/10.1071/CP19039
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Abstract

Pasture legumes must be adequately and effectively nodulated in order to reach nitrogen-fixation targets. Of 225 pasture paddocks sampled across the Central Tablelands, Central West, Monaro and Riverina regions of New South Wales, 93% had inadequate legume nodulation. Legume content was significantly higher in the mixed faming zone (>50%, Central West and Riverina) than the permanent pasture zone (26%, Central Tablelands; 28% Monaro). Available phosphorus (P) was below critical levels in 40% of paddocks sampled and sulfur (S) in 73% of paddocks; >35% of all paddocks had soil pHCa <5.0. Deficiency of P was more prevalent in the Central Tablelands (63% of paddocks), whereas S deficiency occurred more frequently in the Central West (95% of paddocks). Legume nodule scores were associated with host legume species, soil pH, available P and/or S, and cation exchange capacity, which collectively accounted for 73% of variation. For Trifolium spp., at soil pHCa >5.55, nodulation was predicted to be near adequate (score 3.95, where adequate = 4). At pHCa <5.55, higher available S resulted in a higher nodulation score (2.42) than in paddocks where S was deficient (score 0–1.97). These results suggest that improving the capacity of legumes to supply nitrogen should focus on addressing soil acidity and plant nutrition, specifically P and S.

Item Type: Journal Article
Murdoch Affiliation: Centre for Rhizobium Studies
Publisher: CSIRO Publishing
Copyright: © 2019 CSIRO
URI: http://researchrepository.murdoch.edu.au/id/eprint/54034
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