Nodules or not – a survey of pasture legume nodulation in central and southern NSW

Belinda Hackney1, 2, Janelle Jenkins3, Jo Powells4, Clare Edwards5, Susan Orgill6, Sofie DeMeyer7, Tom Edwards8, John Howieson7, Ron Yates7

1 Central West Local Land Services, 42 Sherriff St, Forbes, NSW, 2871, belinda.hackney@lls.nsw.gov.au

2 Graham Centre for Agricultural Innovation, Charles Sturt University and NSW Department of Primary Industries, Wagga Wagga, NSW 2650

3 Riverina Local Land Services, 64 Fitzroy St, Tumut, NSW, 2420

4 South East Local Land Services, 26 Soho St, Cooma, NSW, 2620

5 Central Tablelands Local Land Services, 112 Market St, Mudgee, NSW, 2850

6 NSW Department of Primary Industries, Pine Gully Rd, Wagga Wagga, NSW, 2650

7 Murdoch University, 90 South St, Murdoch, WA, 6150

8 Department of Agriculture and Food Western Australia, Melinijinup Rd, Esperance, WA, 6450

Abstract

Two hundred and twenty-five paddocks were sampled across the central and southern regions of NSW to quantify the nodulation status of pasture legumes in existing pasture paddocks. Results of this survey found that 90% or more of all paddocks had inadequate nodulation and in some regions up to 20% of sampled paddocks had no nodules present on plants sampled. Based on soil pH levels, clover and medic micro-symbionts would be expected to perform sub-optimally in more than 70 and 90% of sampled paddocks respectively. Inadequate levels of key plant nutrients, particularly sulphur, were prevalent across all regions. The results of the survey indicate that the provision of nitrogen via biological nitrogen fixation may be limited and considerably less than that commonly reported in the literature. It appears there is a lack of awareness of this issue within the industry and determining nodulation of representative plant roots carefully excavated from the soil is a first and critical step in assessing nitrogen fixation potential of a legume-based pasture paddock. Addressing the issue of poor nodulation is likely to require amelioration of widespread soil acidity issues and provision of soil nutrients essential for symbiotic nitrogen fixation.

 

Host

The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

Photo Credits

David Marland Photography david_marland@hotmail.com Southern Farming Systems Agriculture Victoria

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