Getting pulses into the sweetest spot

Pulse plans bolstered for acid soils

Legumes & Pulses
SARDI research leader Ross Ballard says field trials have demonstrated the effectiveness of growing faba beans and lentils on acidic soils.

SARDI research leader Ross Ballard says field trials have demonstrated the effectiveness of growing faba beans and lentils on acidic soils.

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Hardy pulse crop options and agronomy investigated for problem soils.

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Growers with acid soils have often had to miss out on the benefits of being part of Australias burgeoning pulse industry in recent years.

Pulses can be hardy against many constraints, with chickpeas rated one of the most drought-hardy crops in the rotation. But what they dont like is an acid soil.

This means growers wanting a pulse phase on acid soils have been restricted to crops such as lupins and faba beans.

A major issue has been getting rhizobia, critical in inoculating pulse crops, with acid tolerance. GRDC-funded research is showing some promising breakthroughs in this field.

Rhizobium bacteria have a symbiotic relationship with legume plants, 'infecting' the roots with nodules that fix atmospheric nitrogen for the plant to grow.

Pulse crops provide excess nitrogen in the soil for the following years crop. Growers will inoculate the seed with rhizobia prior to planting to promote nodulation.

Rates of nodulation on the acid soils of southern Australia have generally been poor, hence the search for new rhizobia strains with improved acid tolerance.

It is hoped the new strains of rhizobia will lead growers to plant pulse crops on paddocks with pH as low as 4.5.

The new strains are improving nodulation and ultimately that results in better crop vigour early in the growing season, as well as improved nitrogen fixation and yield. - SARDI research leader Ross Ballard

The GRDC-funded work, conducted by the South Australian Research and Development Institute (SARDI), has made breakthroughs on faba beans and lentils.

Research leader Ross Ballard says field trials had demonstrated the effectiveness of the new strains in nodulating faba beans and lentils on acidic soils.

He says the new strains of rhizobia had dramatically improved nodulation compared with commercial strains when applied at recommended rates of inoculation in acid conditions.

Increases in faba bean nodulation of about 30 per cent have been consistently measured with the new strains, where soil pH is less than 5.0 when measured in calcium chloride.

The new strains are improving nodulation and ultimately that results in better crop vigour early in the growing season, as well as improved nitrogen fixation and yield, he says.

The rhizobia could be available commercially as early as 2022, but it would be a stop-gap measure to manage soil acidity, and should not replace liming, he said.

More information: Ross Ballard, SARDI, 08 8429 2216, ross.ballard@sa.gov.au

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