Rhizobia survival and new methods to improve nodulation in tropical legumes

The Rhizobia survival and new methods to improve nodulation in tropical legumes project looked at ways to better establish rhizobia for pasture legumes.

The Review of productivity decline in sown grass pastures identified legumes as the best long-term solution to the losses of up to 50% in productivity that occur with ‘rundown’ across huge areas of tropical grass pastures in Queensland and northern New South Wales.

When legumes are introduced to these sown pastures they can increase available soil nitrogen to sustain grass production. However, their contribution to soil nitrogen is often inhibited by commercial inoculation practices that limit effective nodulation of legumes, their subsequent growth and therefore their contribution to soil nitrogen. There is a great opportunity to improve inoculation practices and so lift productivity across the northern beef industry.

This project tested the effectiveness of rhizobia in sub-tropical pastures and evaluated new approaches with the potential to improve rhizobia establishment, and legume nodulation for nitrogen fixation and greater legume growth. Glasshouse trials assessed the effectiveness of ‘native’ rhizobia in soils collected from across the region. However, field trials were used to assess these new inoculation approaches in the hot, dry environments in which perennial tropical legumes are typically sown.

These trials and their results were discussed with graziers participating in the Improving productivity of rundown sown grass pastures project to determine the most practical methods for commercial properties and develop recommendations for their use across the region. The ‘rhizobia’ project then supported the ‘rundown’ project to demonstrate these recommendations on commercial farms. The results and outputs of the project were also shared with participants of the ‘sub-tropical pastures project in the new MLA Southern Feedbase Initiative which identified rhizobia and inoculation practices as a critical area for future RDE investment.

For more details please refer to the final report summary and download the final report (B.NBP.0748) (PDF, 1.1 MB) from the Meat & Livestock Australia website.

When: 1 July 2012 to 30 June 2015

Contact: Brian Johnson

Collaborator: Department of Agriculture and Fisheries