SWEET SORGHUM IN AUSTRALIA
A CROP THAT THRIVES in hot, dry conditions with minimal water requirements? And can be processed in idle sugarcane mills? Sounds like sweet sorghum might do well in Australia.
Winter never comes to the Pilbara. Only the Atacama Desert receives more sunshine and less rain. This remote region of Australia’s northwest is prized for its palette of rusty reds, burnt orange and yellow hues.
Now Lawrence Kirton wants to introduce a new colour: green. Despite the parched conditions, Kirton, who heads Perth-based company Aggrow Energy, thinks the place is perfect for sweet sorghum. And he’s grown the crop here to prove it.
And Ian O’hara, a researcher from the Centre for Tropical Crops and Biocommodities at QUT, recently completed a three-year study confirming sweet sorghum’s potential in Australia.
In Queensland, as in India, a lot of sugarcane factories sit idle several months a year. “Sweet sorghum may have some opportunities as a crop to extend the sugarcane crushing season in Queensland,” O’hara says. “But the companies really seriously looking at sweet sorghum are looking in areas where sugarcane is not currently grown.”
Such as Aggrow Energy and their Pilbara project. The mineral-rich region is better known for mining than farming, and Kirton sees an opportunity in the wastewater from mining. At the height of the mining boom, companies were pumping almost 300 billion litres of water a year out of their mines and into the river: the pumps consumed 3 billion litres of diesel.
Kirton plans to use that water to irrigate a biofuel crop that the mines could use as a renewable alternative to fossil fuels to drive their pumps and trucks. The plantation would provide employment opportunities for traditional owners looking to move back to their lands.
The company assessed several energy crops, but sweet sorghum was a clear favourite. “We planted the seed at just under 50 degrees, and everyone said it wouldn’t grow. What happened was the seed germinated in 48 hours – normally sorghum takes a week,” Kirton says. The plants thrived under the Pilbara irrigated conditions, growing so fast it was possible to produce three crops per year.
The end of the mining boom has slowed Kirton’s expansion plans, however. In February 2016, the Woodie Woodie manganese mine Aggrow Energy had partnered with throughout the trial was mothballed, after manganese prices collapsed from US$5 per tonne in 2014 to $1.80 per tonne. “We’re in discussions with other mines,” Kirton says.
Kirton – a Zimbabwean by birth – says sweet sorghum could be grown anywhere the weather is warm enough. “I’d love to take this technology back to central Africa,” he says. “As a biofuel crop, if the climate is correct, we don’t believe there’s anything to touch it.”
FOR THE OWNERS of the mill, the motivation for introducing sweet sorghum to the region is clear. For the scientists at ICRISAT, this field trial is one small step in a wider mission to alleviate poverty across the drylands.
The commercial farmers gathered at the Madhucon mill are relatively well off. They aren’t the subsistence farmers ICRISAT would ideally target. “The major purpose of this initiative is to make the best use of the existing infrastructure,” Rao explains. Once sweet sorghum is established as a commercially viable crop, subsistence farmers could grow it to share the benefit.
Like any would-be superhero, the plant has its weaknesses. It thrives in heat, but can’t tolerate cold – growing it outside the tropics is not an option. Keeping insect pests away from its juice can be a challenge. And its use as a dual-purpose crop that can feed humans as well as their cars could be undermined by the decreasing human consumption of sorghum grain. Though consumption in Africa is increasing, in India the locals see it as a poor man’s food and aspire to eat wheat or rice, even though sorghum is nutritionally superior to both.
ICRISAT is trying to address this end of the sweet sorghum value chain too, creating demand through its Smart Foods marketing initiative to incorporate it into Western-style food products such as breakfast cereals. Perhaps sorghum might one day grace the menu of fashionable Western cafes, the way traditional grains such as quinoa and faro now do.
AT THE MEETING by the mill, the farmers want to know what price they will get for the sweet sorghum they grow. It’s a fair question. Even by exploiting the existing infrastructure at the mill, when oil prices are low – as they were at the time of writing – biofuel margins are likely to be vapour thin. Just how thin, at this stage in the trial, is a chicken-and-egg question. Until the trial has progressed, and they know how much sugar the crop will yield, the amount the mill will be able to pay the farmers long-term is unknown.
In the end, though, the towering sweet sorghum plants practically sold themselves. As we strolled between the rows, the scientists cut a few stalks and measured the sugar content of the juice with a handheld device known as a refractometer. Sweet sorghum may be new to the sugarcane farmers, but sugar content is a concept they know. In the end, the mill was able to strike a deal with enough farmers – helped by the free seed from ICRISAT during the trial phase – to move the project forward.
At the time of publication, the gradual scale-up of sweet sorghum production around the Madhucon mill was progressing. The initial test with a few local farmers had promising results, says Ashok Kumar, who now leads the ICRISAT sweet sorghum team. “Some farmers got very high yields,” he says, beating typical sweet sorghum yields by almost 20%. But the farmers are new to the crop, and some will need a little more help. “The farmers need to be trained on sweet sorghum cultivation to achieve higher yields,” he adds. Sweet sorghum crushing at the mill was a success, requiring no modification to the machinery used to crush sugarcane. Kumar and his colleagues plan to enrol more farmers in a larger-scale trial, although persuading farmers to grow the unfamiliar crop remains a challenge. Meanwhile, other sugar mills in the region are joining the project.
So far, the Madhucon sweet sorghum experiment seems to be working. It’s slow progress – but then, jatropha is a salient reminder of what happens to those who rush in.
India is far from the only country on the cusp of commercialising sweet sorghum as a biofuel crop. The US, Brazil and China are all weighing its potential as part of the transition to a low-carbon economy – as is Australia (see box).
“Will sweet sorghum ever be the main crop for biofuels? Probably not,” concludes Peter Carberry, ICRISAT’S deputy director general – research. “But for filling niches, there might be an opportunity. Sweet sorghum adds another option for small farmers.”
SO FAR, THE MADHUCON SWEET SORGHUM EXPERIMENT SEEMS TO BE WORKING.