TRIAL work undertaken on Kangaroo Island last year showed promising results for improving the nodulation of broad beans, and the findings could have ramifications for pulse plantings further afield.
Nodulation is crucial for nitrogen fixation.
Last year’s work on broad bean nodulation was led by University of Adelaide senior extension officer Maarten Ryder, with assistance from PIRSA Land Management senior consultant Lyn Dohle at Kingscote.
Dr Ryder said there had been a history of problems with poor nodulation on KI’s acid soils.
“Growers of faba beans in other parts of south eastern SA also have issues with poor nodulation on acidic soils,” he said.
Funding for the trial on KI was secured through the GRDC’s regional cropping solutions network.
Three field trials were set up in May last year.
The first involved a replicated small plot trial looking at various lime treatments to increase soil pH in the furrow and also two new strains of rhizobia from SARDI – SRDI954 and VetchW181.
Each treatment was replicated four times.
The second trial compared the acid-tolerant rhizobium SRDI954 from SARDI to the standard commercial rhizobia.
Again, each treatment was replicated four times.
In the third trial, different combinations of Group F rhizobia, Alosca granules and freeze-dried rhizobia were applied as liquid in-furrow in six treatments, with and without other products, and were compared to a seed coating of rhizobia.
Dr Ryder said the first two trials using the new strains, developed by SARDI senior scientist Ross Ballard and soil scientist Liz Farquharson, showed the most promise.
“Prior to this trial work last year the strains had only been tested on peas in a glasshouse, they hadn’t been tested out in the field,” Dr Ryder said.
In the first trial it was evident that nodulation of the new strains were superior to the standard commercial treatment.
Nodulation is scored between zero and five, with the standard treatment scoring 1.5 in the trial, compared to the VetchW181 treatment on 3.2 and SRDI954 on 3.3.
A score of more than 2.5 is considered good nodulation.
Along with the higher average scores, the treatments produced more consistent nodulation.
The second trial also showed impressive results, with the mean nodulation scores across the site 3.6 for SRDI954, compared to 2.5 for the commercial strain.
SRDI954 also showed consistency across the trial site, while the standard treatment had varying results.
Bean yield was 8.45 per cent higher in the SRDI954-inoculated rows.
