New acid tolerant rhizobium strains for inoculant groups E and F

Take home messages

• Inoculation of pulses including lentil, field pea, vetch and faba bean is widely recommended, particularly where the pulse is sown into paddocks with acidic soils or, where the pulse or another in the same inoculation group has not been sown for a number of years.
• Two new high-performing rhizobia strains for inoculant Group E (lentil, field pea, vetch) and Group F (faba and broad bean) with improved nitrogen fixation and acid soil tolerance will be available for the 2024 season.
• The new strains (Group E - WSM4643, Group F- SRDI-969) will replace strain (WSM-1455).
• The new strains can provide optimal nodulation down to pHCa 5.0 and improved nodulation to pHCa 4.5.

Summary

Two new high-performing rhizobia strains for inoculant Group E (lentil, field pea, vetch) and Group F (faba and broad bean) with improved acid soil tolerance will be available for the 2024 season. The rhizobia for group of legumes are especially sensitive to soil acidity below pHCa 5.5. As a result, expansion of pulse sowings into areas containing acid soils has been restricted because of poor nodulation, plant establishment and growth. With GRDC investment, two improved inoculant strains have been selected to facilitate successful establishment and improve production of field pea, lentil and vetch, and faba and broad beans on acidic soils. The new strains (Group E - WSM4643, Group F- SRDI-969) will replace strain (WSM-1455) and can provide optimal nodulation down to pHCa 5.0 and improved nodulation to pHCa 4.5. For faba bean, the new strain (SRDI-969) has shown an average improvement of 65% in nodulation and 24% in N fixation in field trials on acidic soils. For field pea, lentil and vetch, the new rhizobia strain (WSM-4643) has shown an average improvement in nodulation of 30% and yield of 15%, with yield responses observed at one-third of sites.

The new rhizobia strains should be used in conjunction with an effective liming strategy.

Two GRDC fact sheets (QR code links below) have been produced which how and where strains can be used and the benefits associated with the improved rhizobia strains.

New Group E Rhizobia inoculant for field pea, lentil and vetch Factsheet

New Group F Rhizobia inoculant for faba an broad bean Factsheet

Acknowledgements

The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC, the author would like to thank them for their continued support.

The Authors would also like to acknowledge the contributions of following research collaborators for their contributions and support to trial work; Maarten Ryder, Judith Rathjen, Frank Henry, Jason Brand, Rachael Whitworth, Barry Haskins, Mark Seymour, Jacob Giles, Amy Gutsche, and project statistical support from Beverly Gogel (University of Wollongong) and the SAGI South Team.

Contact details

Elizabeth Farquharson
(08) 8429 2243
liz.farquharson@sa.gov.au