Legume inoculation snapshot

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Photo of legume plant roots
A GRDC-invested survey indicates that 95 per cent of growers check their legume plant roots for nodulation. PHOTO: Clarisa Collis

A new snapshot of legume inoculation use has emerged from a 2017 national survey of 154 growers who collectively farm more than 400,000 hectares across the country.

The University of Adelaide’s Dr Matthew Denton says the study found about 94 per cent of growers surveyed inoculate major pulse crops – lupins, chickpeas, faba beans and mungbeans – while about 90 per cent of growers inoculate field peas.

Lagging behind these inoculated crops were lentils and legume pastures, which the GRDC-invested survey showed had the lowest rates of inoculation. But Dr Denton says a lot of legume pasture seed is pre-inoculated at the time of purchase.

Of the growers who inoculate legumes, about 80 per cent used peat slurry inoculant and the other 20 per cent used freeze-dried, granular or pre-inoculated seed options.

“Many growers therefore use multiple inoculant types,” he says.

The survey showed growers saw low profitability, unreliable production and disease risk as the main barriers to planting more legumes. But despite this, many said they had already maximised legume plantings on 25 to 33 per cent of their cropping area.

About 80 per cent said the crops’ ability to fix nitrogen in the soil had helped reduce nitrogen fertiliser costs.

The survey also showed more than half of growers planted legumes into dry soil. For example, 56 to 66 per cent of lentils, faba beans and lupins were dry sown, whereas just 10 to 30 per cent of mungbeans, chickpeas and peanuts were dry sown. “Current work is focused on better understanding inoculant use under dry conditions to help identify the best inoculants for sowing prior to seasonal breaking rains,” Dr Denton says.

Another finding was that growers are generally knowledgeable about inoculants, rhizobia and legume nitrogen fixation, although about 10 per cent were not aware of the specific inoculant groups for different legumes: “Of some concern was the survey finding that 22 per cent of growers thought peat slurry inoculants could be mixed with fertilisers,” Dr Denton says.

More information

Dr Matthew Denton, 08 8313 1098
matthew.denton@adelaide.edu.au

Useful resources

School of Agriculture, Food & Wine

Tips & Tactics: Legumes And Nitrogen Fixation